Fox Tempest is a financially motivated threat actor that operates a malware-signing-as-a-service (MSaaS)  used by other cybercriminals to more effectively distribute malicious code, including ransomware. The threat actor abuses Microsoft Artifact Signing to generate short-lived, fraudulent code-signing certificates to appear legitimately signed, allowing malware to evade security controls.

Fox Tempest has created over a thousand certificates and established hundreds of Azure tenants and subscriptions to support its operations. Microsoft has revoked over one thousand code signing certificates attributed to Fox Tempest. In May 2026, Microsoft’s Digital Crimes Unit (DCU), with support from industry partner Resecurity, disrupted Fox Tempest’s MSaaS offering, targeting the infrastructure and access model that enables its broader criminal use.

Microsoft Threat Intelligence observed Fox Tempest’s operations enabling the deployment of Rhysida ransomware by threat actors such as Vanilla Tempest, as well as the distribution of other malware families including Oyster, Lumma Stealer, and Vidar. The consistency, scale, and downstream impact of the resulting attack activity demonstrate that Fox Tempest is a vital operator within the broader cybercrime ecosystem.

In this blog, we examine how Fox Tempest’s MSaaS operation functioned and how it enabled the delivery of trusted, signed malware across the cybercrime ecosystem. We also provide Microsoft Defender detections, indicators of compromise (IOCs), and mitigation recommendations to help organizations identify and disrupt similar activity.

Fox Tempest’s role and impact

Fox Tempest doesn’t directly target victims but instead provides supporting services that enable ransomware operations by other threat actors. Microsoft Threat Intelligence has tracked Fox Tempest since September 2025. Microsoft Threat Intelligence has linked the actor to various ransomware groups including Vanilla Tempest, Storm-0501, Storm-2561, and Storm-0249, who have all leveraged Fox Tempest-signed malware in active intrusions. Malware delivery in these attacks have included use of legitimate purchased advertisements, malvertising, and SEO poisoning.

Cryptocurrency analysis associated with Fox Tempest has identified clear links tying the actor to ransomware affiliates responsible for delivering several prominent ransomware families, including INC, Qilin, Akira, and others, with observed proceeds in the millions. Based on the scale of the MSaaS offering, Microsoft Threat Intelligence assesses that Fox Tempest is a well-resourced group handling infrastructure creation, customer relations, and financial transactions.

The downstream impact of these operations has resulted in attacks against a broad range of industry sectors, including healthcare, education, government, and financial services, impacting organizations globally including, but not limited to the United States, France, India, and China.

Fox Tempest’s malware signing as a service infrastructure

Fox Tempest’s MSaaS capability was available through the website signspace[.]cloud, a now defunct service that was disrupted by DCU, which enabled other threat actors to fraudulently obtain short-lived Microsoft-issued certificates that were valid for only 72 hours, obtained through Artifact Signing (previously named Azure Trusted Signing). This use of short-life certificates from a trusted source allowed malware and ransomware to masquerade as legitimate software (like AnyDesk, Teams, Putty, and Webex) to bypass security controls, significantly increasing the likelihood of execution and successful delivery. Fox Tempest offered this MSaaS capability to the ransomware ecosystem since at least May 2025.

To obtain legitimate signed certificates through Artifact Signing, the requestor must pass detailed identify validation processes in keeping with industry standard verifiable credentials (VC), which suggests the threat actor very likely used stolen identities based in the United States and Canada to masquerade as a legitimate entity and obtain the necessary digital credentials for signing. The SignSpace website was built on Artifact Signing and enabled secure file signing through an admin panel and user page, leveraging Azure subscriptions, certificates, and a structured database for managing users and files. A GitHub repository, called code‑signing‑service, included configuration files and technical details that directly linked it to the infrastructure behind signspace[.]cloud.

The signspace[.]cloud service has two unique modeling groupings: the admin and the customers. The admin is responsible for maintaining the tooling, account creation, and infrastructure, while the customers provide files to be fraudulently code signed. Customers who accessed the service could upload malicious files to be signed using Fox Tempest-controlled certificates.

Below are examples of the signspace[.]cloud portal as seen by Fox Tempest’s customers:

In February 2026, Microsoft Threat Intelligence observed a notable shift in Fox Tempest’s operational infrastructure. Fox Tempest transitioned to providing customers with pre-configured virtual machines (VMs) hosted on US-based virtual private server provider Cloudzy’s infrastructure, allowing threat actors to upload their malicious files directly to Fox Tempest‑controlled environments and receive signed binaries in return. This infrastructure evolution reduced friction for customers, improved operational security for Fox Tempest, and further streamlined the delivery of malicious but trusted, signed malware at scale. Microsoft’s Digital Crimes Unit (DCU) disrupted this infrastructure and continues to partner with Cloudzy to identify and disrupt related infrastructure.

Below is an example of the Fox Tempest-provided VM environment as seen by customers:

Inside the VM, Fox Tempest provided files that are used to sign code:

• The first file, metadata.json, was a configuration file that pointed to an Azure‑hosted endpoint which also included the signing account and certificate profile.
• The second file, test.js, is an example of a file provided by Fox Tempest that had been digitally signed to demonstrate their signing capabilities to customers.
• The third file, PS code sample.txt, contains the PowerShell script they used to sign customer‑submitted files using certificates under Fox Tempest control.

Threat actors using Fox Tempest’s MSaaS offering paid thousands of dollars to get their malicious code signed, as shown below with the Google Form detailing the service’s pricing model. Actors filled out the form before being added to a queue to submit payment and gain access to a VM. The form (written in both English and Russian) asks the user to choose a selected plan from a price list of $5000 USD, $7500 USD, or $9000 USD, with a mention that higher paying plans receive priority in the queue sequence.

Fox Tempest engaged directly with customers using a Telegram channel, EV Certs for Sale by SamCodeSign under the user account arbadakarba2000. All signing activity occurred using a Fox Tempest-provided email address associated with a very small number of IP addresses.

Case study: Fox Tempest enables Vanilla Tempest attacks

Vanilla Tempest began using Fox Tempest’s MSaaS service as early as June 2025. Through this service, Vanilla Tempest uploaded malicious payloads such as trojanized Microsoft Teams installers, which Fox Tempest would fraudulently signed to appear legitimate. Vanilla Tempest would then distribute these signed binaries through legitimately purchased advertisements that redirected users searching for Microsoft Teams to attacker‑controlled advertisements and fraudulent download pages.

Victims were presented with a malicious MSTeamsSetup.exe in place of the legitimate client, reflecting a broader pattern of Vanilla Tempest frequently abusing trusted software brands to lure victims and establish initial access. Execution of the counterfeit installer resulted in the deployment of the Oyster backdoor (also known as Broomstick), a modular, multistage implant that establishes persistent remote access, initiates command‑and‑control (C2) communications, collects host‑level information, and enables the delivery of additional payloads. By masquerading as a widely deployed enterprise collaboration tool hiding behind a fraudulently signed binary, Vanilla Tempest’s Oyster payload was likely able to evade casual detection and blend into normal enterprise activity. In some observed cases, Vanilla Tempest also deployed Rhysida ransomware within victim environments using the same process.

Defending against Fox Tempest-enabled attacks

To defend against Fox Tempest tactics, techniques, and procedures (TTPs) and similar activity, Microsoft recommends the following mitigation measures:

• Read the human-operated ransomware threat overview for advice on developing a holistic security posture to prevent ransomware, including credential hygiene and hardening recommendations.
• Turn on cloud-delivered protection in Microsoft Defender Antivirus or the equivalent for your antivirus product to cover rapidly evolving attacker tools and techniques. Cloud-based machine learning protections block a huge majority of new and unknown variants.
• Turn on Safe Links and Safe Attachments in Microsoft Defender for Office 365.
• Encourage users to use Microsoft Edge and other web browsers that support Microsoft Defender SmartScreen, which identifies and blocks malicious websites, including phishing sites, scam sites, and sites that host malware.
• Turn on tenant-wide tamper protection features to prevent attackers from stopping security services or using antivirus exclusions. Without tamper protection, attackers could simply turn off Microsoft Defender Antivirus without the need to acquire higher privileges.
  • Customers running Intune or Microsoft Defender for Endpoint Security Configuration can enable DisableLocalAdminMerge to prevent modification of antivirus exclusions via GPO. 
  • In addition to tamper protection, you can also enable and configure Microsoft Defender Antivirus always-on protection in Group Policy.
  • If there is an issue with a device during roll out of various antivirus features, the device can be placed in troubleshooting mode to turn off tamper protection temporarily without impacting the wider organizational security policy.
• Microsoft Defender XDR customers can turn on attack surface reduction rules to prevent several of the infection vectors of this threat. These rules, which can be configured by any user, offer significant hardening against targeted attacks. In observed attacks, Microsoft customers who had the following rules turned on could mitigate the attack in the initial stages and prevent hands-on-keyboard activity:
  • Use advanced protection against ransomware

Microsoft Defender detections

Microsoft Defender customers can refer to the list of applicable detections below. Microsoft Defender coordinates detection, prevention, investigation, and response across endpoints, identities, email, apps to provide integrated protection against attacks like the threat discussed in this blog.

Microsoft Security Copilot

Microsoft Security Copilot is embedded in Microsoft Defender and provides security teams with AI-powered capabilities to summarize incidents, analyze files and scripts, summarize identities, use guided responses, and generate device summaries, hunting queries, and incident reports.

Customers can also deploy AI agents, including the following Microsoft Security Copilot agents, to perform security tasks efficiently:

• Threat Intelligence Briefing agent
• Phishing Triage agent
• Threat Hunting agent
• Dynamic Threat Detection agent

Security Copilot is also available as a standalone experience where customers can perform specific security-related tasks, such as incident investigation, user analysis, and vulnerability impact assessment. In addition, Security Copilot offers developer scenarios that allow customers to build, test, publish, and integrate AI agents and plugins to meet unique security needs.

Threat intelligence reports

Microsoft Defender XDR customers can use the following threat analytics reports in the Defender portal (requires license for at least one Defender XDR product) to get the most up-to-date information about the threat actor, malicious activity, and techniques discussed in this blog. These reports provide the intelligence, protection information, and recommended actions to prevent, mitigate, or respond to associated threats found in customer environments.

Microsoft Defender XDR threat analytics

• Actor profile: Fox Tempest
• Actor profile: Vanilla Tempest
• Threat Overview profile: Human-operated ransomware
• Activity profile: Vanilla Tempest leverages fake Microsoft Teams setup to deliver Oyster backdoor

Microsoft Security Copilot customers can also use the Microsoft Security Copilot integration in Microsoft Defender Threat Intelligence, either in the Security Copilot standalone portal or in the embedded experience in the Microsoft Defender portal to get more information about this threat actor.

Indicators of compromise

Learn more

For the latest security research from the Microsoft Threat Intelligence community, check out the Microsoft Threat Intelligence Blog.

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The post Exposing Fox Tempest: A malware-signing service operation appeared first on Microsoft Security Blog.

While under Microsoft’s Secure Future Initiative (SFI), default security has been strengthened by design, defenders still need to make the most out of customer-facing security capabilities. Therefore, this blog recommends countermeasures and controls across identity, endpoints, data apps, and network layers to help harden enterprise Teams environments. To frame these defenses, we first examine relevant stages of the attack chain. This guidance complements, but doesn’t repeat, the guidance built into the Microsoft Security Development Lifecycle (SDL) as outlined in the Teams Security Guide;  we will instead focus on guidance for disrupting adversarial objectives based on the relatively recently observed attempts to exploit Teams infrastructure and capabilities.

Attack chain

Reconnaissance

Every Teams user account is backed by a Microsoft Entra ID identity. Each team member is an Entra ID object, and a team is a collection of channel objects. Teams may be configured for the cloud or a hybrid environment and supports multi-tenant organizations (MTO) and cross-tenant communication and collaboration. There are anonymous participants, guests, and external access users. From an API perspective, Teams is an object type that can be queried and stored in a local database for reconnaissance by enumerating directory objects, and mapping relationships and privileges. For example, federation tenant configuration indicates whether the tenant allows external communication and can be inferred from the API response queries reflecting the effective tenant federation policy.

While not unique to Teams, there are open-source frameworks that can specifically be leveraged to enumerate less secure users, groups, and tenants in Teams (mostly by repurposing the Microsoft Graph API or gathering DNS), including ROADtools, TeamFiltration, TeamsEnum, and MSFT-Recon-RS. These tools facilitate enumerating teams, members of teams and channels, tenant IDs and enabled domains, as well as permissiveness for communicating with external organizations and other properties, like presence. Presence indicates a user’s current availability and status outside the organization if Privacy mode is not enabled, which could then be exploited if the admin has not disabled external meetings and chat with people and organizations outside the organization (or at least limited it to specified external domains).

Many open-source tools are modular Python packages including reusable libraries and classes that can be directly imported or extended to support custom classes, meaning they are also interoperable with other custom open-source reconnaissance and discovery frameworks designed to identify potential misconfigurations.

Resource development

Microsoft continuously enhances protections against fraudulent Microsoft Entra ID Workforce tenants and the abuse of free tenants and trial subscriptions. As these defenses grow stronger, threat actors are forced to invest significantly more resources in their attempts to impersonate trusted users, demonstrating the effectiveness of our layered security approach. . This includes threat actors trying to compromise weakly configured legitimate tenants, or even actually purchasing legitimate ones if they have confidence they could ultimately profit. It should come as no surprise that if they can build a persona for social engineering, they will take advantage of the same resources as legitimate organizations, including custom domains and branding, especially if it can lend credibility to impersonating internal help desk, admin, or IT support, which could then be used as a convincing pretext to compromise targets through chat messaging and phone calls. Sophisticated threat actors try to use the very same resources used by trustworthy organizations, such as acquiring multiple tenants for staging development or running separate operations across regions, and using everyday Teams features like scheduling private meetings through chat, and audio, video and screen-sharing capabilities for productivity.

Initial access

Tech support scams remain a generally popular pretext for delivery of malicious remote monitoring and management (RMM) tools and information-stealing malware, leading to credential theft, extortion, and ransomware. There are always new variants to bypass security awareness defenses, such as the rise in email bombing to create a sense of stress and urgency to restore normalcy. In 2024, for instance, Storm-1811 impersonated tech support, claiming to be addressing junk email issues that it had initiated. They used RMM tools to deliver the ReedBed malware loader of ransomware payloads and remote command execution. Meanwhile, Midnight Blizard has successfully impersonated security and technical support teams to get targets to verify their identities under the pretext of protecting their accounts by entering authentication codes that complete the authentication flow for breaking into the accounts.

Similarly in May, Sophos identified a 3AM ransomware (believed to be a rebranding of BlackSuit) affiliate adopting techniques from Storm-1811, including flooding employees with unwanted emails followed by voice and video calls on Teams impersonating help desk personnel, claiming they needed remote access to stop the flood of junk emails. The threat actor reportedly spoofed the IT organization’s phone number.

With threat actors leveraging deepfakes, perceived authority helps make this kind of social engineering even more effective. Threat actors seeking to spoof automated workflow notifications and interactions can naturally extend to spoofing legitimate bots and agents as they gain more traction, as threat actors are turning to language models to facilitate their objectives.

Prevalent threat actors associated with ransomware campaigns, including the access broker tracked as Storm-1674 have used sophisticated red teaming tools, like TeamsPhisher, to distribute DarkGate malware and other malicious payloads over Teams. In December 2024, for example, Trend Micro reported an incident in which a threat actor impersonated a client during a Teams call to persuade a target to install AnyDesk. Remote access was reportedly then used also to deploy DarkGate. Threat actors may also just use Teams to gain initial access through drive-by-compromise activity to direct users to malicious websites.

Widely available admin tools, including AADInternals, could be leveraged to deliver malicious links and payloads directly into Teams. Teams branding (like any communications brand asset) makes for effective bait, and has been used by adversary-in-the-middle (AiTM) actors like Storm-00485. Threat actors could place malicious advertisements in search results for a spoofed app like Teams to misdirect users to a download site hosting credential-stealing malware. In July 2025, for instance, Malwarebytes reported observing a malvertising campaign delivering credential-stealing malware through a fake Microsoft Teams for Mac installer.

Whether it is a core app that is part of Teams, an app created by Microsoft, a partner app validated by Microsoft, or a custom app created by your own organization—no matter how secure an app—they could still be spoofed to gain a foothold in a network. And similar to leveraging a trusted brand like Teams, threat actors will also continue to try and take advantage of trusted relationships as well to gain Teams access, whether leveraging an account with access or abusing delegated administrator relationships to reach a target environment.

Persistence

Threat actors employ a variety of persistence techniques to maintain access to target systems—even after defenders attempt to regain control. These methods include abusing shortcuts in the Startup folder to execute malicious tools, or exploiting accessibility features like Sticky Keys (as seen in this ransomware case study). Threat actors could try to create guest users in target tenants or add their own credentials to a Teams account to maintain access.

Part of the reason device code phishing has been used to access target accounts is that it could enable persistent access for as long as the tokens remain valid. In February, Microsoft reported that Storm-2372 had been capturing authentication tokens by exploiting device code authentication flows, partially by masquerading as Microsoft Teams meeting invitations and initiating Teams chats to build rapport, so that when the targets were prompted to authenticate, they would use Storm-2372-generated device codes, enabling Storm-2372 to steal the authenticated sessions from the valid access tokens.

Teams phishing lures themselves can sometimes be a disguised attempt to help threat actors maintain persistence. For example, in July 2025, the financially motivated Storm-0324 most likely relied on TeamsPhisher to send Teams phishing lures to deliver a custom malware JSSloader for the ransomware operator Sangria Tempest to use as an access vector to maintain a foothold.

Execution

Apart from admin accounts, which are an attractive target because they come with elevated privileges, threat actors try and trick everyday Teams users into clicking links or opening files that lead to malicious code execution, just like through email.

Privilege escalation

If threat actors successfully compromise accounts or register actor-controlled devices, they often times  try to change permission groups to escalate privileges. If a threat actor successfully compromises a Teams admin role, this could lead to abuse of the permissions to use the admin tools that belong to that role.

Credential access

With a valid refresh token, actors can impersonate users through Teams APIs. There is no shortage of administrator tools that can be maliciously repurposed, such as AADInternals, to intercept access to tokens with custom phishing flows. Tools like TeamFiltration could be leveraged just like for any other Microsoft 365 service for targeting Teams. If credentials are compromised through password spraying, threat actors use tools like this to request OAuth tokens for Teams and other services. Threat actors continue to try and bypass multifactor authentication (MFA) by repeatedly generating authentication prompts until someone accepts by mistake, and try to compromise MFA by adding alternate phone numbers or intercepting SMS-based codes.

For instance, the financially motivated threat actor Octo Tempest uses aggressive social engineering, including over Teams, to take control of MFA for privileged accounts. They consistently socially engineer help desk personnel, targeting federated identity providers using tools like AADInternals to federate existing domains, or spoof legitimate domains by adding and then federating new domains to forge tokens.

Discovery

To refine targeting, threat actors analyze Teams configuration data from API responses, enumerate Teams apps if they obtain unauthorized access, and search for valuable files and directories by leveraging toolkits for contextualizing potential attack paths. For instance, Void Blizzard has used AzureHound to enumerate a compromised organization’s Microsoft Entra ID configuration and gather details on users, roles, groups, applications, and devices. In a small number of compromises, the threat actor accessed Teams conversations and messages through the web client. AADInternals can also be used to discover Teams group structures and permissions.

The state-sponsored actor Peach Sandstorm has delivered malicious ZIP files through Teams, then used AD Explorer to take snapshots of on-premises Active Directory database and related files.

Lateral movement

A threat actor that manages to obtain Teams admin access (whether directly or indirectly by purchasing an admin account through a rogue online marketplace) could potentially leverage external communication settings and enable trust relationships between organizations to move laterally. In late 2024, in a campaign dubbed VEILdrive by Hunters’ Team AXON, the financially motivated cybercriminal threat actors Sangria Tempest and Storm-1674 used previously compromised accounts to impersonate IT personnel and convince a user in another organization through Teams to accept a chat request and grant access through a remote connection.

Collection

Threat actors often target Teams to try and collect information from it that could help them to accomplish their objectives, such as to discover collaboration channels or high-privileged accounts. They could try to mine Teams for any information perceived as useful in furtherance of their objectives, including pivoting from a compromised account to data accessible to that user from OneDrive or SharePoint. AADInternals can be used to collect sensitive chat data and user profiles. Post-compromise, GraphRunner can leverage the Microsoft Graph API to search all chats and channels and export Teams conversations.

Command and control

Threat actors attempt to deliver malware through file attachments in Teams chats or channels. A cracked version of Brute Ratel C4 (BRc4) includes features to establish C2 channels with platforms like Microsoft Teams by using their communications protocols to send and receive commands and data.

Post-compromise, threat actors can use red teaming tool ConvoC2 to send commands through Microsoft Teams messages using the Adaptive Card framework to embed data in hidden span tags and then exfiltrate using webhooks. But threat actors can also use legitimate remote access tools to try and establish interactive C2 through Teams.

Exfiltration

Threat actors may use Teams messages or shared links to direct data exfiltration to cloud storage under their control. Tools like TeamFiltration include an exfiltration module that rely on a valid access token to then extract recent contacts and download chats and files through OneDrive or SharePoint.

Impact

Threat actors try to use Teams messages to support financial theft through extortion, social engineering, or technical means.

Octo Tempest has used communication apps, including Teams to send taunting and threatening messages to organizations, defenders, and incident response teams as part of extortion and ransomware payment pressure tactics. After gaining control of MFA through social engineering password resets, they sign in to Teams to identify sensitive information supporting their financially motivated operations.

Mitigation and protection guidance

Strengthen identity protection

• Enable sign-in and user risk policies in Microsoft Entra ID Protection. Enforce access controls based on sign-in risk. Users must be registered for Microsoft Entra multifactor authentication before sign-in risk policies can be triggered.
• Configure just-in-time access to privileged roles. Use Microsoft Entra Privileged Identity Management (PIM) (preview) to provide as-needed and just-in-time access to Microsoft 365 roles to reduce standing privileges and limit exposure.

Harden endpoint security

• Use configuration analyzer to strengthen security posture. Identify and remediate security policies that are less secure than the Standard or Strict protection profiles in preset security policies.
• Keep Teams clients, browsers, OS, and dependencies updated.
• Enable network protection and web protection capability in Defender for Endpoint.
• Enable cloud-delivered protection in Defender Antivirus. Cloud-delivered protection enables sharing detection status between Microsoft 365 and Defender for Endpoint. Real-time protection blocking, including on-access scanning, is not availablewhen Defender Antivirus is running only in passive mode. You can turn on endpoint detection and response (EDR) in block mode even if Defender Antivirus isn’t your primary antivirus solution. EDR in block mode detects and remediates malicious items on the device post-breach.
• Protect security settings from being disabled or changed with tamper protection.
• Require device compliance policies with Conditional Access. Enhance conditional access, to the extent available, with real-time enforcement through Continuous Access Evaluation (CAE), so that user session revocation is enforced in near-real time. Teams is supported as a cloud app in Microsoft Entra, so that conditional access policies apply when a user signs in. The Teams desktop application supports AppLocker, but we recommend using App Control, if feasible. Use Defender for Endpoint to enforce device compliance with Microsoft Intune.
• If your organization utilizes another remote support tool such as Remote Help, disable or remove Quick Assist as a best practice, if it isn’t used within your environment.
• Understand and use attack surface reduction capabilities in your environment to prevent common techniques used in combination with Teams threat activity as part of your first line of defense.
  • Block Win32 API calls from Office macros
  • Block Office applications from injecting code into other processes
  • Block Office applications from creating executable content
  • Block all Office applications from creating child processes
  • Block credential stealing from the Windows local security authority subsystem
  • Block executable files from running unless they meet a prevalence, age, or trusted list criterion
  • Block execution of potentially obfuscated scripts
  • Block persistence through WMI event subscription
  • Block process creations originating from PSExec and WMI commands
  • Block use of copied or impersonated system tools
  • Block JavaScript or VBScript from launching downloaded executable content
  • Use advanced protection against ransomware

Secure Teams clients and apps

Implementing some of these recommendations will require Teams Administrator permissions.

• Follow the Microsoft Teams recommendations on Microsoft Secure Score.
• Manage Teams for iOS and Android with Microsoft Intune.
  • Apply app-based Conditional Access.
  • Create Intune app protection policies
• Configure Teams protection in Defender for Office 365.
  • Turn on Safe Attachments.
  • Set up Safe Links policies.
  • Use SharePoint Online PowerShell to prevent users from downloading malicious files.
  • Use the Defender portal (or PowerShell) to create an alert policy for detected files.
  • Configure Zero-hour auto purge (ZAP). ZAP can retroactively detect existing malicious chat messages in Teams. Set the quarantine policy that is used for detections.
• Secure external access to Teams with Microsoft Entra ID.
• Manage guest access in Teams.
• Manage call settings in Teams. Inbound calls originating from the Public Switched Telephone Network (PSTN) on a tenant global level can be blocked.
• Use meeting and event policies to control the features that are available to organizers and participants.
• Use the Teams admin center or PowerShell to require anonymous users and people from untrusted organizations to complete a verification check before joining the meeting. 
• Control access to meetings with lobby policies (who can bypass it and eligibility for admitting participants).
• Manage who can present and request control to generally prevent external users by default without business justification from being able to automatically request control over a shared window or screen.
• Manage Teams recording policies for meetings and events (as well as for town halls).
• Manage external meetings and chat.
  • Specify which types of external meetings and chat to allow and which users should have access to these features. You can change the default setting to limit external access to only allowed domains or block specific domains and subdomains. By blocking external communication with trial-only tenants, users that do not have any purchased seats are not able to search and contact your users via chat, Teams calls, and meetings.
  • You can prevent users that are not managed by an organization from starting conversations or prevent chat with them. If you choose to allow anonymous users in your environment, you can verify their identities by email code to join meetings (Premium).
• Monitor Teams activities using activity policies in Defender for Cloud Apps. If external users are enabled, you can monitor their presence. Defender for Cloud Apps integrates directly with Microsoft 365 audit logs. Office 365 Cloud Apps Security has access to the features of Defender for Cloud Apps to support the Office 365 app connector.
  • Specify which users and groups can use Microsoft Teams apps or a copilot agent and control it on a per-app basis. You can change the default setting letting users install apps by default. Evaluate the compliance, security, and data handling information of an app and also understand the permissions requested by the app before you allow an app to be used.

Protect sensitive data

• Use meeting templates, sensitivity labels, and admin policies together for sensitive meetings.
  • Teams data is encrypted in transit and at rest in Microsoft services, between services, and between clients and services. For heightened confidentiality, you can also use end-to-end encryption in advanced meeting protection that is available with the Teams Premium add-on license. This encrypts audio, video, and video-based screen sharing at its origin and decrypts it at its destination.
  • You can use end-to-end encryption for up to 200 meeting participants and turn off the ability to copy and paste from meeting chats. The Premium add-on license may be required to prevent users from sharing sensitive information when attending external meetings and restrict recording to organizers in meetings with sensitive information.
• Block chats and channel messages that contain sensitive information with Microsoft Purview Data Loss Prevention (DLP) for Teams.
• Manage sharing settings for SharePoint and OneDrive.

Raise awareness

• Get started using attack simulation training. The Teams attack simulation training is currently in private preview. Build organizational resilience by raising awareness of QR code phishing, deepfakes including voice, and about protecting your organization from tech support and ClickFix scams.
• Train developers to follow best practices when working with the Microsoft Graph API. Apply these practices when detecting, defending against, and responding to malicious techniques targeting Teams.
  • Using server-side code to make Graph API calls that require access tokens helps protect against token interception or leakage. We recommend using the most secure authentication flow available. For more information, see Microsoft identity platform and OAuth 2.0 Resource Owner Password Credentials.
• Learn more about some of the frequent initial access threats impacting SharePoint servers. SharePoint is a front end for Microsoft Teams and an attractive target.

Configure detection and response

• Verify the auditing status of your organization in Microsoft Purview to make sure you can investigate incidents. In Threat Explorer, Content malware includes files detected by Safe Attachments for Teams, and URL clicks include all user clicks in Teams.
• Customize how users report malicious messages, and then view and triage them.
  • Security Operations (SecOps) should be enabled to proactively manage false negatives and false positives, and to hunt for threats and detections. They should triage and investigate from the Defender XDR incidents queue in the Defender portal.
  • If user reporting of messages is turned on in the Teams admin center, it also needs to be turned on in the Defender portal. We encourage you to submit user reported Teams messages to Microsoft here.
• Search the audit log for events in Teams.
  • Refer to the table listing the Microsoft Teams activities logged in the Microsoft 365 audit log. With the Office 365 Management Activity API, you can retrieve information about user, admin, system, and policy actions and events including from Entra activity logs.
• Familiarize yourself with relevant advanced hunting schema and available tables.
  • Advanced hunting supports guided and advanced modes. You can use the advanced hunting queries in the advanced hunting section to hunt with these tables for Teams-related threats.
  • Several tables covering Teams-related threats are available in preview and populated by Defender for Office 365, including MessageEvents, MessagePostDeliveryEvents, MessageUrlInfo, and UrlClickEvents. These tables provide visibility into ZAP events and URLs in Teams messages, including allowed or blocked URL clicks in Teams clients. You can join these tables with others to gain more comprehensive insight into the progression of the attack chain and end-to-end threat activity.
• Connect Microsoft 365 to Microsoft Defender for Cloud Apps.
  • To hunt for Teams messages without URLs, use the CloudAppEvents table, populated by Defender for Cloud Apps. This table also includes chat monitoring events, meeting and Teams call tracking, and behavioral analytics. To make sure advanced hunting tables are populated by Defender for Cloud Apps data, go to the Defender portal and select Settings > Cloud apps > App connectors. Then, in the Select Microsoft 365 components page, select the Microsoft 365 activities checkbox. Control Microsoft 365 with built-in policies and policy templates to detect and notify you about potential threats.
• Create Defender for Cloud Apps threat detection policies.
  • Many of the detection types enabled by default apply to Teams and do not require custom policy creation, including sign-ins from geographically distant locations in a short time, access from a country not previously associated with a user, unexpected admin actions, mass downloads, activity from anonymous IP addresses, or from a device flagged as malware-infected by Defender for Endpoint, as well as Oauth app abuse (when app governance is turned on).
  • Defender for Cloud Apps enables you to identify high-risk use and cloud security issues, detect abnormal user behavior, and prevent threats in your sanctioned cloud apps. You can integrate Defender for Cloud Apps with Microsoft Sentinel (preview) or use the supported APIs.
• Detect and remediate illicit consent grants in Microsoft 365.
  • Refer to the compromised and malicious applications incident response playbook. This playbook includes relevant guidance for identifying and investigating malicious activity on third-party apps installed in Teams, custom apps using the Graph API for Teams, or OAuth abuse involving Teams permissions.
• Discover and enable the Microsoft Sentinel data lake in Defender XDR. Sentinel data lake brings together security logs from data sources like Microsoft Defender and Microsoft Sentinel, Microsoft 365, Microsoft Entra ID, Purview, Intune, Microsoft Resource Graph, firewall and network logs, identity and access logs, DNS, plus sources from hundreds of connectors and solutions, including Microsoft Defender Threat Intelligence. Advanced hunting KQL queries can be run directly on the data lake. You can analyze the data using Jupyter notebooks.

Microsoft Defender detections

Microsoft Defender XDR customers can refer to the list of applicable detections below. Microsoft Defender XDR coordinates detection, prevention, investigation, and response across endpoints, identities, email, apps to provide integrated protection against attacks like the threat discussed in this blog.

Customers with provisioned access can also use Microsoft Security Copilot in Microsoft Defender to investigate and respond to incidents, hunt for threats, and protect their organization with relevant threat intelligence.

Microsoft Defender XDR

The following alerts might indicate threat activity associated with this threat.

• Malicious sign in from a risky IP address
• Malicious sign in from an unusual user agent
• Account compromised following a password-spray attack
• Compromised user account identified in Password Spray activity
• Successful authentication after password spray attack
• Password Spray detected via suspicious Teams client (TeamFiltration)

Microsoft Entra ID Protection

Any type of sign-in and user risk detection might also indicate threat activity associated with this threat. An example is listed below. These alerts, however, can be triggered by unrelated threat activity.

• Impossible travel
• Anomalous Microsoft Teams login from web client

Microsoft Defender for Endpoint

The following alerts might indicate threat activity associated with this threat.

• Suspicious module loaded using Microsoft Teams

The following alerts might also indicate threat activity associated with this threat. These alerts, however, can be triggered by unrelated threat activity and are not monitored in the status cards provided with this report.

• Suspicious usage of remote management software

Microsoft Defender for Office 365

The following alerts might indicate threat activity associated with this threat.

• Malicious link shared in Teams chat
• User clicked a malicious link in Teams chat

When Microsoft Defender for Cloud Apps is enabled, the following alert might indicate threat activity associated with this threat.

• Potentially Malicious IT Support Teams impersonation post mail bombing

The following alerts might also indicate threat activity associated with this threat. These alerts, however, can be triggered by unrelated threat activity and are not monitored in the status cards provided with this report.

• A potentially malicious URL click was detected
• Possible AiTM phishing attempt

Microsoft Defender for Identity

The following Microsoft Defender for Identity alerts can indicate associated threat activity:

• Account enumeration reconnaissance
• Suspicious additions to sensitive groups
• Account Enumeration reconnaissance (LDAP)

Microsoft Defender for Cloud Apps

The following alerts might indicate threat activity associated with this threat.

• Consent granted to application with Microsoft Teams permissions
• Risky user installed a suspicious application in Microsoft Teams
• Compromised account signed in to Microsoft Teams
• Microsoft Teams chat initiated by a suspicious external user
• Suspicious Teams access via Graph API

The following alerts might also indicate threat activity associated with this threat. These alerts, however, can be triggered by unrelated threat activity and are not monitored in the status cards provided with this report.

• Possible mail exfiltration by app

Microsoft Security Copilot

Microsoft Security Copilot customers can use the Copilot in Defender embedded experience to check the impact of this report and get insights based on their environment’s highest exposure level in Threat analytics, Intel profiles, Intel Explorer and Intel projects pages of the Defender portal.

You can also use Copilot in Defender to speed up analysis of suspicious scripts and command lines by inspecting them below the incident graph on an incident page and in the timeline on the Device entity page without using external tools.

Threat intelligence reports

Microsoft customers can use the following reports in Microsoft products to get the most up-to-date information about the threat actor, malicious activity, and techniques discussed in this blog. These reports provide the intelligence, protection information, and recommended actions to prevent, mitigate, or respond to associated threats found in customer environments.

Microsoft Defender XDR threat analytics

• Technique Profile: Threats targeting Microsoft Teams

Microsoft Security Copilot customers can also use the Microsoft Security Copilot integration in Microsoft Defender Threat Intelligence, either in the Security Copilot standalone portal or in the embedded experience in the Microsoft Defender portal to get more information about this threat actor.

Hunting queries

Microsoft Defender XDR

Advanced hunting allows you to view and query all the data sources available within the unified Microsoft Defender portal, which include Microsoft Defender XDR and various Microsoft security services.

After onboarding to the Microsoft Sentinel data lake, auxiliary log tables are no longer available in Microsoft Defender advanced hunting. Instead, you can access them through data lake exploration Kusto Query Language (KQL) queries in the Defender portal. For more information, see KQL queries in the Microsoft Sentinel data lake.

You can design and tweak custom detection rules using the advanced hunting queries and set them to run at regular intervals, generating alerts and taking response actions whenever there are matches. You can also link the generated alert to this report so that it appears in the Related incidents tab in threat analytics. Custom detection rule can automatically take actions on devices, files, users, or emails that are returned by the query. To make sure you’re creating detections that trigger true alerts, take time to review your existing custom detections by following the steps in Manage existing custom detection rules.

Detect potential data exfiltration from Teams

let timeWindow = 1h; 
let messageThreshold = 20; 
let trustedDomains = dynamic(["trustedpartner.com", "anothertrusted.com"]); 
CloudAppEvents 
| where Timestamp > ago(1d) 
| where ActionType == "MessageSent" 
| where Application == "Microsoft Teams" 
| where isnotempty(AccountObjectId)
| where tostring(parse_json(RawEventData).ParticipantInfo.HasForeignTenantUsers) == "true" 
| where tostring(parse_json(RawEventData).CommunicationType) in ("OneOnOne", "GroupChat") 
| extend RecipientDomain = tostring(parse_json(RawEventData).ParticipantInfo.ParticipatingDomains[1])
| where RecipientDomain !in (trustedDomains) 
| extend SenderUPN = tostring(parse_json(RawEventData).UserId)
| summarize MessageCount = count() by bin(Timestamp, timeWindow), SenderUPN, RecipientDomain
| where MessageCount > messageThreshold 
| project Timestamp, MessageCount, SenderUPN, RecipientDomain
| sort by MessageCount desc  

Detect mail bombing that sometimes precedes technical support scams on Microsoft Teams

EmailEvents 
   | where Timestamp > ago(1d) 
   | where DetectionMethods contains "Mail bombing" 
   | project Timestamp, NetworkMessageId, SenderFromAddress, Subject, ReportId

Detect malicious Teams content from MessageEvents

MessageEvents 
   | where Timestamp > ago(1d) 
   | where ThreatTypes has "Phish"                
       or ThreatTypes has "Malware"               
       or ThreatTypes has "Spam"                    
   | project Timestamp, SenderDisplayName, SenderEmailAddress, RecipientDetails, IsOwnedThread, ThreadType, IsExternalThread, ReportId

Detect communication with external help desk/support representatives

MessageEvents  
| where Timestamp > ago(5d)  
 | where IsExternalThread == true  
 | where (RecipientDetails contains "help" and RecipientDetails contains "desk")  
	or (RecipientDetails contains "it" and RecipientDetails contains "support")  
	or (RecipientDetails contains "working" and RecipientDetails contains "home")  
	or (SenderDisplayName contains "help" and SenderDisplayName contains "desk")  
	or (SenderDisplayName contains "it" and SenderDisplayName contains "support")  
	or (SenderDisplayName contains "working" and SenderDisplayName contains "home")  
 | project Timestamp, SenderDisplayName, SenderEmailAddress, RecipientDetails, IsOwnedThread, ThreadType

Expand detection of communication with external help desk/support representatives by searching for linked process executions

let portableExecutable  = pack_array("binary.exe", "portable.exe"); 
let timeAgo = ago(30d);
MessageEvents
  | where Timestamp > timeAgo
  | where IsExternalThread == true
  | where (RecipientDetails contains "help" and RecipientDetails contains "desk")
      or (RecipientDetails contains "it" and RecipientDetails contains "support")
      or (RecipientDetails contains "working" and RecipientDetails contains "home")
  | summarize spamEvent = min(Timestamp) by SenderEmailAddress
  | join kind=inner ( 
      DeviceProcessEvents  
      | where Timestamp > timeAgo
      | where FileName in (portableExecutable)
      ) on $left.SenderEmailAddress == $right.InitiatingProcessAccountUpn 
  | where spamEvent < Timestamp

Surface Teams threat activity using Microsoft Security Copilot

Microsoft Security Copilot in Microsoft Defender comes with a query assistant capability in advanced hunting. You can also run the following prompt in Microsoft Security Copilot pane in the Advanced hunting page or by reopening Copilot from the top of the query editor:

Show me recent activity in the last 7 days that matches attack techniques described in the Microsoft Teams technique profile. Include relevant alerts, affected users and devices, and generate advanced hunting queries to investigate further.

Microsoft Sentinel

Possible Teams phishing activity

This query specifically monitors Microsoft Teams for one-on-one chats involving impersonated users (e.g., 'Help Desk', 'Microsoft Security').

let suspiciousUpns = DeviceProcessEvents
    | where DeviceId == "alertedMachine"
    | where isnotempty(InitiatingProcessAccountUpn)
    | project InitiatingProcessAccountUpn;
    CloudAppEvents
    | where Application == "Microsoft Teams"
    | where ActionType == "ChatCreated"
    | where isempty(AccountObjectId)
    | where RawEventData.ParticipantInfo.HasForeignTenantUsers == true
    | where RawEventData.CommunicationType == "OneonOne"
    | where RawEventData.ParticipantInfo.HasGuestUsers == false
    | where RawEventData.ParticipantInfo.HasOtherGuestUsers == false
    | where RawEventData.Members[0].DisplayName in ("Microsoft  Security", "Help Desk", "Help Desk Team", "Help Desk IT", "Microsoft Security", "office")
    | where AccountId has "@"
    | extend TargetUPN = tolower(tostring(RawEventData.Members[1].UPN))
    | where TargetUPN in (suspiciousUpns)

Files uploaded to Teams and access summary

This query identifies files uploaded to Microsoft Teams chat files and their access history, specifically mentioning operations from SharePoint. It allows tracking of potential file collection activity through Teams-related storage.

OfficeActivity 
    | where RecordType =~ "SharePointFileOperation"
    | where Operation =~ "FileUploaded" 
    | where UserId != "app@sharepoint"
    | where SourceRelativeUrl has "Microsoft Teams Chat Files" 
    | join kind= leftouter ( 
       OfficeActivity 
        | where RecordType =~ "SharePointFileOperation"
        | where Operation =~ "FileDownloaded" or Operation =~ "FileAccessed" 
        | where UserId != "app@sharepoint"
        | where SourceRelativeUrl has "Microsoft Teams Chat Files" 
    ) on OfficeObjectId 
    | extend userBag = bag_pack(UserId1, ClientIP1) 
    | summarize make_set(UserId1, 10000), make_bag(userBag, 10000) by TimeGenerated, UserId, OfficeObjectId, SourceFileName 
    | extend NumberUsers = array_length(bag_keys(bag_userBag))
    | project timestamp=TimeGenerated, UserId, FileLocation=OfficeObjectId, FileName=SourceFileName, AccessedBy=bag_userBag, NumberOfUsersAccessed=NumberUsers
    | extend AccountName = tostring(split(UserId, "@")[0]), AccountUPNSuffix = tostring(split(UserId, "@")[1])
    | extend Account_0_Name = AccountName
    | extend Account_0_UPNSuffix = AccountUPNSuffix

References

• A familiar playbook with a twist: 3AM ransomware actors dropped virtual machine with vishing and Quick Assist (Sophos)
• convoC2 (Cxnuri0n)
• EvilSlackbot (Drew-Sec)
• Fake Microsoft Teams Emails Phish for Credentials (Dark Reading)
• Fake Microsoft Teams for Mac delivers Atomic Stealer (Malwarebytes)
• GraphRunner (Dafthack)
• Inside the Microsoft Teams attack matrix: unpacking the frontier in collaboration threats (Cyberdom)
• Microsoft 365 Attack Surfaces: Elevation of Privilege Vulnerabilities (CoreView)
• Microsoft 365 secure configuration baselines (CISA)
• MSFT-Recon-RS (Copyleftdev)
•  Ongoing Email Bombing Campaigns leading to Remote Access and Post-Exploitation (eSentire)
• Playing for the wrong team: dangerous functionalities in Microsoft Teams enable phishing and malware delivery by attackers (Proofpoint)
• Signed. Sideloaded. Compromised! (Ontinue)
• Sophos MDR tracks two ransomware campaigns using “email bombing,” Microsoft Teams “vishing” (Sophos)
• TeamsEnum (Secure Systems Engineering)
• TeamsPhisher (Octoberfest7)
• Thinking Outside the Mailbox: Modernized Phishing Techniques (Praetorian)
• Unmasking VEILDrive: Threat Actors Exploit Microsoft Services for C2 (Hunters)
• Vishing via Microsoft Teams Facilitates DarkGate Malware Intrusion (Trend Micro)

Learn more

For the latest security research from the Microsoft Threat Intelligence community, check out ff

To get notified about new publications and to join discussions on social media, follow us on LinkedIn, X (formerly Twitter), and Bluesky.

To hear stories and insights from the Microsoft Threat Intelligence community about the ever-evolving threat landscape, listen to the Microsoft Threat Intelligence podcast.

The post Disrupting threats targeting Microsoft Teams appeared first on Microsoft Security Blog.

Lumma Stealer (also known as LummaC2) is a malware as a service (MaaS) offering that is capable of stealing data from various browsers and applications such as cryptocurrency wallets and installing other malware. Microsoft Threat Intelligence tracks the threat actor who developed and maintains the Lumma malware, command-and-control (C2) infrastructure, and the Lumma MaaS as Storm-2477. Affiliates who pay Storm-2477 for the service and operate their own Lumma campaigns access a panel to build the malware binary and manage the C2 communications and stolen information. We have observed ransomware threat actors like Octo Tempest, Storm-1607, Storm-1113, and Storm-1674 using Lumma Stealer in campaigns.

Unlike earlier infostealers that relied heavily on bulk spam or exploits, Lumma Stealer exemplifies a shift toward multi-vector delivery strategies. Its operators demonstrate resourcefulness and proficiency in impersonation tactics. The Lumma Stealer distribution infrastructure is flexible and adaptable. Operators continually refine their techniques, rotating malicious domains, exploiting ad networks, and leveraging legitimate cloud services to evade detection and maintain operational continuity. This dynamic structure enables operators to maximize the success of campaigns while complicating efforts to trace or dismantle their activities.

The growth and resilience of Lumma Stealer highlights the broader evolution of cybercrime and underscores the need for layered defenses and industry collaboration to counter threats. In this blog post, we share our analysis of Lumma Stealer and its infrastructure and provide guidance on how users and organizations can protect themselves from this threat. Microsoft remains committed to sharing insights, developing protections, and working with partners across industries to disrupt malicious ecosystems and safeguard users worldwide.

Lumma Stealer delivery techniques

Lumma Stealer leverages a broad and evolving set of delivery vectors. Campaigns often combine multiple techniques, dynamically adapting to evade detection and increase infection success rates. Delivery infrastructure is designed to be ephemeral, shifting rapidly across domains, platforms, and geographies to avoid takedowns.

• Phishing emails: Lumma Stealer emails impersonate known brands and services to deliver links or attachments. These campaigns involve expertly crafted emails designed to evoke urgency, often masquerading as urgent hotel reservation confirmations or pending cancellations. The emails lead victims to cloned websites or malicious servers that deploy the Lumma payload to the targets’ environment.

• Malvertising: Threat actors inject fake advertisements into search engine results, targeting software-related queries such as “Notepad++ download” or “Chrome update.” Clicking these poisoned links leads users to cloned websites that closely mimic legitimate vendors but instead deliver the Lumma Stealer.
• Drive-by download on compromised websites: Threat actors were observed compromising groups of legitimate websites, typically through a particular vulnerability or misconfiguration. They modify site content by inserting malicious JavaScript. The JavaScript runs when sites are visited by unsuspecting users, leading to delivery of a payload, intermediary script, or displaying further lures to convince users to perform an action.
• Trojanized applications: In many campaigns, cracked or pirated versions of legitimate applications are bundled with Lumma binaries and distributed through file-sharing platforms. These modified installers often contain no visible payload during installation, executing the malware silently post-launch.
• Abuse of legitimate services and ClickFix: Public repositories like GitHub are abused and populated with scripts and binaries, often disguised as tools or utilities. A particularly deceptive method involves fake CAPTCHA pages, commonly observed in the ClickFix ecosystem. Targets are instructed to copy malicious commands into their system’s Run utility under the pretense of passing a verification check. These commands often download and execute Lumma directly in memory, using Base64 encoding and stealthy delivery chains.
• Dropped by other malware: Microsoft Threat Intelligence observed other loaders and malware such as DanaBot delivering Lumma Stealer as an additional payload.

All these mechanisms reflect threat actor behavior that prioritizes abuse of user trust, manipulation of legitimate infrastructure, and multi-layered distribution chains designed to evade both technical and human defenses. The following sections discuss some examples of campaigns where the mentioned distribution methods were used to deliver Lumma Stealer.

Drive-by download campaign leveraging EtherHiding and ClickFix to deliver Lumma

In early April 2025, Microsoft observed a cluster of compromised websites leveraging EtherHiding and ClickFix techniques to install Lumma Stealer. EtherHiding is a technique that involves leveraging smart contracts on blockchain platforms like Binance Smart Chain (BSC) to host parts of malicious code. Traditional methods of blocking malicious code, such as IP or domain blocking or content-based detections, are less effective against EtherHiding because the code is embedded in the blockchain. Meanwhile, in the ClickFix technique, a threat actor attempts to take advantage of human problem-solving tendencies by displaying fake error messages or prompts that instruct target users to fix issues by copying, pasting, and launching commands that eventually result in the download of malware.

In this campaign, the JavaScript injected into compromised websites directly contacted BSC to retrieve the ClickFix code and lure, which was then presented to the target. Users needed to click the “I’m not a robot” prompt, at which point a command was copied into their clipboard. Users were then instructed to paste and launch this command via the Windows Run prompt. The command downloaded and initiated further code using mshta from check.foquh[.]icu.

Email campaign targeting organizations in Canada to deliver Lumma Stealer

On April 7, 2025, Microsoft Threat Intelligence observed an email campaign consisting of thousands of emails targeting organizations in Canada. The emails used invoice lures for a fitness plan or an online education platform. The emails’ subject lines were personalized to include recipient-specific details such as “Invoice for [recipient email]”. Notably, the attack chain utilized multiple tools available for purchase on underground forums for traffic filtering and social engineering.

The emails contained URLs leading to the Prometheus traffic direction system (TDS) hosted on numerous compromised sites. The TDS in turn, redirected users to the attacker-controlled website binadata[.]com that hosted the ClickFix social engineering framework. Like the previous campaign, targets were instructed to click a “I’m not a robot” prompt and run malicious code via a multi-step process. The malicious code was an mshta command that downloaded and executed JavaScript from the IP address 185.147.125[.]174. The JavaScript ran a PowerShell command that downloaded more PowerShell code, which finally downloaded and launched a Lumma Stealer executable. Notably, Xworm malware was also bundled into this executable.

Lumma Stealer malware analysis

The core Lumma Stealer malware is written in a combination of C++ and ASM. The malware author designed it as a MaaS offering. Threat actors can access the panel to build the malware binary and manage the C2 communications and stolen information. The core binary is obfuscated with advanced protection such as low-level virtual machine (LLVM core), Control Flow Flattening (CFF), Control Flow Obfuscation, customized stack decryption, huge stack variables, and dead codes, among others. These techniques are implemented on the critical functions to make static analysis difficult, as these can cause tools like Hex-Rays’ IDA fail to produce equivalent decompiled codes. In addition, most of the critical APIs are implemented via low-level syscalls and Heavens Gate Technology.

Lumma Stealer is designed to steal from browsers based on Chromium and Mozilla technology, including Microsoft Edge. In addition, it has the capability to install other malware or plugins, including Clipboard stealer plugin and coin miners, either by downloading to disk or directly in memory.

Process injection and process hollowing

Lumma loader may use process hollowing to inject its malicious payload into legitimate system processes like msbuild.exe, regasm.exe, regsvcs.exe, and explorer.exe. This technique enables execution under the guise of a trusted binary to bypass behavioral detection and endpoint monitoring tools.

Information-stealing capabilities

Lumma Stealer targets a comprehensive set of user data using a specialized collection routine for each type of data. These capabilities have evolved over time, and Microsoft Threat Intelligence has recently observed that the instructions for the target credentials are specified in the configuration file retrieved from the active C2 server. The configuration file is divided into several parts: the “ex” section that pertains to the target list of apps for cryptocurrency wallets and extensions, and “c” sections that pertain to the list of applications and configuration details for browsers, user file’s locations, and other applications.

• Browser credentials and cookies: Lumma Stealer extracts saved passwords, session cookies, and autofill data from Chromium (including Edge), Mozilla, and Gecko-based browsers.
• Cryptocurrency wallets and extensions: Lumma Stealer actively searches for wallet files, browser extensions, and local keys associated with wallets like MetaMask, Electrum, and Exodus.
• Various applications: Lumma Stealer targets data from various virtual private networks (VPNs) (.ovpn), email clients, FTP clients, and Telegram applications.  
• User documents: Lumma Stealer harvests files found on the user profiles and other common directories, especially those with .pdf, .docx, or .rtf extensions.
• System metadata: Lumma Stealer collects host telemetry such as CPU information, OS version, system locale, and installed applications for tailoring future exploits or profiling victims.

C2 communication

Lumma Stealer maintains a robust C2 infrastructure, using a combination of hardcoded tier 1 C2s that are regularly updated and reordered, and fallback C2s hosted as Steam profiles and Telegram channels that also point to the tier 1 C2s. The Telegram C2, if available, is always checked first, while the Steam C2 is checked only when all the hardcoded C2s are not active. To further hide the real C2 servers, all the C2 servers are hidden behind the Cloudflare proxy.

While Lumma Stealer affiliates share the tier 1 C2s, there is a capability to add a personal tier 1 C2 domain for an extra cost. The diagram below shows an overview of the Lumma Stealer infrastructure. All traffic is encrypted by HTTPS.

Different types of obfuscation are applied to each set of C2 servers. For example, the hardcoded list of C2s, and including the Telegram fallback C2 URL are protected with ChaCha20 crypto, while the Steam profile fallback C2 URL is encrypted using custom stack-based crypto algorithm that can change on each version of Lumma malware.

We have identified up to six versions of Lumma Stealer, and while each of these versions focuses on improving techniques to evade antivirus detections, there are also several changes in the C2 communication protocol and formats such as the C2 domains, URI path, POST data, and others. The core Lumma malware stores the build date as part of the embedded configuration to keep track of improvements, but in our investigation, we tracked major changes using the labels “version 1” through “version 6”.

Lumma Stealer keeps track of the active C2 for sending the succeeding commands. Each command is sent to a single C2 domain that is active at that point. In addition, each C2 command contains one or more C2 parameters specified as part of the POST data as form data. The parameters are:  

• act: Indicates the C2 command. Note: This C2 parameter no longer exists in Lumma version 6.
• ver: Indicates C2 protocol version. This value is always set to 4.0 and has never changed since the first version Lumma.
• lid (for version 5 and below)/uid (for version 6): This ID identifies the Lumma client/operator and its campaign.
• j (for version 5 and below )/cid (for version 6): This is an optional field that identifies additional Lumma features.
• hwid: Indicates the unique identifier for the victim machine.
• pid: Used in SEND_MESSAGE command to identify the source of the stolen data. A value of 1, indicates it came from the Lumma core process.

The following are some of the most common Lumma Stealer C2 commands and associated parameters:

• PING / LIFE: Initial command to check if the C2 is active. Note: This command does not exist in version 6.
  • act=life
• RECEIVE_MESSAGE: Command to download the stealer’s configuration. As noted above, this contains the specifications on the list of targets.
  • version 3 and below: act=recive_message&ver=4.0&lid=[<lid_value>]&j=[<j_value>]
  • version 4 and 5: act=receive_message&ver=4.0&lid=[<lid_value>]&j=[<j_value>]
  • version 6: uid=<uid_value>&cid=[<cid_value>]
• SEND_MESSAGE: Command to send back stolen data in chunks. The C2 parameters are specified as individual section in the whole POST data. The fields included are act=send_message, hwid, pid, lid/uid, and j/cid. The act field was removed in version 6.
• GET_MESSAGE: Command to download the second configuration. This configuration contains information about the plugins and additional malware to install on the target systems. We have observed that in most cases this command will respond with valid but empty records “[]”, meaning nothing to download. So far, we have observed Lumma Stealer installing an updated version of the Clipboard stealer plugin and coin miners.
  • versions 5 and below: act=get_message&ver=4.0&lid=[<lid_value>]&j=[<j_value>]&hwid=<hwid_value>
  • version 6: uid=<uid_value>&cid=[<cid_value>]&hwid=<hwid_value>

Microsoft Digital Crimes Unit (DCU) engineered tools that identify and map the Lumma Stealer C2 infrastructure. As part of the disruption announced on May 21, Microsoft’s DCU has facilitated the takedown, suspension, and blocking of approximately 2,300 malicious domains that formed the backbone of the Lumma Stealer infrastructure.  More details of this operation are presented in the DCU disruption announcement.

Recommendations

Microsoft Threat Intelligence recommends the following mitigations to reduce the impact of this threat.

Strengthen Microsoft Defender for Endpoint configuration

• Ensure that tamper protection is enabled in Microsoft Defender for Endpoint.
• Enable network protection in Microsoft Defender for Endpoint.
• Turn on web protection.
• Run endpoint detection and response (EDR) in block mode so that Microsoft Defender for Endpoint can block malicious artifacts, even when your non-Microsoft antivirus does not detect the threat or when Microsoft Defender Antivirus is running in passive mode. EDR in block mode works behind the scenes to remediate malicious artifacts that are detected post-breach.    
• Configure investigation and remediation in full automated mode to let Microsoft Defender for Endpoint take immediate action on alerts to resolve breaches, significantly reducing alert volume. 
• Microsoft Defender XDR customers can turn on the following attack surface reduction rules to prevent common attack techniques used by threat actors.
  • Block executable files from running unless they meet a prevalence, age, or trusted list criterion
  • Block execution of potentially obfuscated scripts
  • Block JavaScript or VBScript from launching downloaded executable content
  • Block process creations originating from PSExec and WMI commands
  • Block credential stealing from the Windows local security authority subsystem
  • Block use of copied or impersonated system tools

Strengthen operating environment configuration

• Require multifactor authentication (MFA). While certain attacks such as adversary-in-the-middle (AiTM) phishing attempt to circumvent MFA, implementation of MFA remains an essential pillar in identity security and is highly effective at stopping a variety of threats.
• Leverage phishing-resistant authentication methods such as FIDO Tokens, or Microsoft Authenticator with passkey. Avoid telephony-based MFA methods to avoid risks associated with SIM-jacking.
• Implement Entra ID Conditional Access authentication strength to require phishing-resistant authentication for employees and external users for critical apps.
• Encourage users to use Microsoft Edge with Microsoft Defender SmartScreen, which identifies and blocks malicious websites, including phishing sites, scam sites, and sites that host malware.
• Enable Network Level Authentication for Remote Desktop Service connections.
• Enable Local Security Authority (LSA) protection to block credential stealing from the Windows local security authority subsystem.
• AppLocker can restrict specific software tools prohibited within the organization, such as reconnaissance, fingerprinting, and RMM tools, or grant access to only specific users.

Detection details

Microsoft Defender XDR customers can refer to the list of applicable detections below. Microsoft Defender XDR coordinates detection, prevention, investigation, and response across endpoints, identities, email, apps to provide integrated protection against attacks like the threat discussed in this blog.

Customers with provisioned access can also use Microsoft Security Copilot in Microsoft Defender to investigate and respond to incidents, hunt for threats, and protect their organization with relevant threat intelligence.

Microsoft Defender Antivirus

Microsoft Defender Antivirus detects this threat as the following malware:

• Behavior:Win32/LummaStealer
• Trojan:JS/LummaStealer
• Trojan:MSIL/LummaStealer
• Trojan:Win32/LummaStealer
• Trojan:Win64/LummaStealer
• TrojanDropper:Win32/LummaStealer
• Trojan:PowerShell/Powdow
• Trojan:Win64/Shaolaod
• Behavior:Win64/Shaolaod
• Behavior:Win32/MaleficAms
• Behavior:Win32/ClickFix
• Behavior:Win32/SuspClickFix
• Trojan:Win32/ClickFix
• Trojan:PowerShell/ClickFixObfus
• Behavior:Win32/RegRunMRU
• Trojan:HTML/FakeCaptcha
• Trojan:Script/SuspDown

Microsoft Defender for Endpoint

The following Microsoft Defender for Endpoint alerts might also indicate threat activity related to this threat. Note, however, that these alerts can be also triggered by unrelated threat activity:

• Suspicious command in RunMRU registry
• Possible Lumma Stealer activity
• Information stealing malware activity
• Suspicious PowerShell command line
• Use of living-off-the-land binary to run malicious code
• Possible theft of passwords and other sensitive web browser information
• Suspicious DPAPI Activity
• Suspicious mshta process launched
• Renamed AutoIt tool
• Suspicious phishing activity detected
• Suspicious implant process from a known emerging threat
• A process was injected with potentially malicious code
• Process hollowing detected
• Suspicious PowerShell download or encoded command execution
• A process was launched on a hidden desktop

Microsoft Defender for Office 365

Microsoft Defender for Office 365 identifies and blocks malicious emails. These alerts, however, can also be triggered by unrelated threat activity:

• A potentially malicious URL click was detected
• Email messages containing malicious URL removed after delivery
• Email messages removed after delivery
• A user clicked through to a potentially malicious URL
• Suspicious email sending patterns detected
• Email reported by user as malware or phish

Defender for Office 365 also detects and blocks Prometheus TDS, EtherHiding patterns, ClickFix landing pages.

Microsoft Security Copilot

Security Copilot customers can use the standalone experience to create their own prompts or run the following pre-built promptbooks to automate incident response or investigation tasks related to this threat:

• Incident investigation
• Microsoft User analysis
• Threat actor profile
• Threat Intelligence 360 report based on MDTI article
• Vulnerability impact assessment

Note that some promptbooks require access to plugins for Microsoft products such as Microsoft Defender XDR or Microsoft Sentinel.

Threat intelligence reports

Microsoft customers can use the following reports in Microsoft products to get the most up-to-date information about the threat actor, malicious activity, and techniques discussed in this blog. These reports provide the intelligence, protection information, and recommended actions to prevent, mitigate, or respond to associated threats found in customer environments.

Microsoft Defender Threat Intelligence

• Storm-1865 phishing campaigns over vendor platforms lead to payment data theft and fraudulent charges
• Lumma Stealer
• Malvertising campaign leads to info stealers hosted on GitHub
• ClickFix technique leverages clipboard to run malicious commands

Microsoft Security Copilot customers can also use the Microsoft Security Copilot integration in Microsoft Defender Threat Intelligence, either in the Security Copilot standalone portal or in the embedded experience in the Microsoft Defender portal to get more information about this threat actor.

Hunting queries

Microsoft Defender XDR

Microsoft Defender XDR customers can run the following query to find related activity in their networks:

ClickFix commands execution

Identify ClickFix commands execution.

DeviceRegistryEvents
| where ActionType =~ "RegistryValueSet"
| where InitiatingProcessFileName =~ "explorer.exe"
| where RegistryKey has @"\CurrentVersion\Explorer\RunMRU"
| where RegistryValueData has "✅"
        or (RegistryValueData has_any ("powershell", "mshta", "curl", "msiexec", "^")
             and RegistryValueData matches regex "[\u0400-\u04FF\u0370-\u03FF\u0590-\u05FF\u0600-\u06FF\u0E00-\u0E7F\u2C80-\u2CFF\u13A0-\u13FF\u0530-\u058F\u10A0-\u10FF\u0900-\u097F]")
        or (RegistryValueData has "mshta" and RegistryValueName !~ "MRUList" and RegistryValueData !in~ ("mshta.exe\\1", "mshta\\1"))
        or (RegistryValueData has_any ("bitsadmin", "forfiles", "ProxyCommand=") and RegistryValueName !~ "MRUList")
        or ((RegistryValueData startswith "cmd" or RegistryValueData startswith "powershell")
            and (RegistryValueData has_any ("-W Hidden ", " -eC ", "curl", "E:jscript", "ssh", "Invoke-Expression", "UtcNow", "Floor", "DownloadString", "DownloadFile", "FromBase64String",  "System.IO.Compression", "System.IO.MemoryStream", "iex", "Invoke-WebRequest", "iwr", "Get-ADDomainController", "InstallProduct", "-w h", "-X POST", "Invoke-RestMethod", "-NoP -W", ".InVOKe", "-useb", "irm ", "^", "[char]", "[scriptblock]", "-UserAgent", "UseBasicParsing", ".Content")
              or RegistryValueData matches regex @"[-/–][Ee^]{1,2}[NnCcOoDdEeMmAa^]*\s[A-Za-z0-9+/=]{15,}"))

DPAPI decryption via AutoIT or .NET Framework processes

Identify DPAPI decryption activity originating from AutoIT scripts .NET Framework processes.

DeviceEvents
| where ActionType == "DpapiAccessed"
| where InitiatingProcessVersionInfoInternalFileName == "AutoIt3.exe"
      or InitiatingProcessFolderPath has "\\windows\\microsoft.net\\framework\\"
      or InitiatingProcessFileName =~ "powershell.exe"
| where (AdditionalFields has_any("Google Chrome", "Microsoft Edge") and AdditionalFields has_any("SPCryptUnprotect"))
| extend json = parse_json(AdditionalFields)
| extend dataDesp = tostring(json.DataDescription.PropertyValue)
| extend opType = tostring(json.OperationType.PropertyValue)
| where dataDesp in~ ("Google Chrome", "Microsoft Edge", "Chromium", "Opera", "Opera GX", "IMAP Password", "Brave Browser", "AVG Secure Browser") 
        and opType =~ "SPCryptUnprotect"
| project Timestamp, ReportId, DeviceId, ActionType, InitiatingProcessParentFileName, InitiatingProcessFileName, InitiatingProcessVersionInfoInternalFileName, InitiatingProcessCommandLine, AdditionalFields, dataDesp, opType

Learn more

For the latest security research from the Microsoft Threat Intelligence community, check out the Microsoft Threat Intelligence Blog: https://aka.ms/threatintelblog.

To get notified about new publications and to join discussions on social media, follow us on LinkedIn at https://www.linkedin.com/showcase/microsoft-threat-intelligence, on X (formerly Twitter) at https://x.com/MsftSecIntel, and Bluesky at https://bsky.app/profile/threatintel.microsoft.com.

To hear stories and insights from the Microsoft Threat Intelligence community about the ever-evolving threat landscape, listen to the Microsoft Threat Intelligence podcast: https://thecyberwire.com/podcasts/microsoft-threat-intelligence.

The post Lumma Stealer: Breaking down the delivery techniques and capabilities of a prolific infostealer appeared first on Microsoft Security Blog.

Octo Tempest is a financially motivated collective of native English-speaking threat actors known for launching wide-ranging campaigns that prominently feature adversary-in-the-middle (AiTM) techniques, social engineering, and SIM swapping capabilities. Octo Tempest, which overlaps with research associated with 0ktapus, Scattered Spider, and UNC3944, was initially seen in early 2022, targeting mobile telecommunications and business process outsourcing organizations to initiate phone number ports (also known as SIM swaps). Octo Tempest monetized their intrusions in 2022 by selling SIM swaps to other criminals and performing account takeovers of high-net-worth individuals to steal their cryptocurrency.

Building on their initial success, Octo Tempest harnessed their experience and acquired data to progressively advance their motives, targeting, and techniques, adopting an increasingly aggressive approach. In late 2022 to early 2023, Octo Tempest expanded their targeting to include cable telecommunications, email, and technology organizations. During this period, Octo Tempest started monetizing intrusions by extorting victim organizations for data stolen during their intrusion operations and in some cases even resorting to physical threats.

In mid-2023, Octo Tempest became an affiliate of ALPHV/BlackCat, a human-operated ransomware as a service (RaaS) operation, and initial victims were extorted for data theft (with no ransomware deployment) using ALPHV Collections leak site. This is notable in that, historically, Eastern European ransomware groups refused to do business with native English-speaking criminals. By June 2023, Octo Tempest started deploying ALPHV/BlackCat ransomware payloads (both Windows and Linux versions) to victims and lately has focused their deployments primarily on VMWare ESXi servers. Octo Tempest progressively broadened the scope of industries targeted for extortion, including natural resources, gaming, hospitality, consumer products, retail, managed service providers, manufacturing, law, technology, and financial services.  

In recent campaigns, we observed Octo Tempest leverage a diverse array of TTPs to navigate complex hybrid environments, exfiltrate sensitive data, and encrypt data. Octo Tempest leverages tradecraft that many organizations don’t have in their typical threat models, such as SMS phishing, SIM swapping, and advanced social engineering techniques. This blog post aims to provide organizations with an insight into Octo Tempest’s tradecraft by detailing the fluidity of their operations and to offer organizations defensive mechanisms to thwart the highly motivated financial cybercriminal group.

Analysis 

The well-organized, prolific nature of Octo Tempest’s attacks is indicative of extensive technical depth and multiple hands-on-keyboard operators. The succeeding sections cover the wide range of TTPs we observed being used by Octo Tempest.

Initial access 

Social engineering with a twist

Octo Tempest commonly launches social engineering attacks targeting technical administrators, such as support and help desk personnel, who have permissions that could enable the threat actor to gain initial access to accounts. The threat actor performs research on the organization and identifies targets to effectively impersonate victims, mimicking idiolect on phone calls and understanding personal identifiable information to trick technical administrators into performing password resets and resetting multifactor authentication (MFA) methods. Octo Tempest has also been observed impersonating newly hired employees in these attempts to blend into normal on-hire processes.

Octo Tempest primarily gains initial access to an organization using one of several methods:

• Social engineering
  • Calling an employee and socially engineering the user to either:
    • Install a Remote Monitoring and Management (RMM) utility
    • Navigate to a site configured with a fake login portal using an adversary-in-the-middle toolkit
    • Remove their FIDO2 token
  • Calling an organization’s help desk and socially engineering the help desk to reset the user’s password and/or change/add a multi-factor authentication token/factor
• Purchasing an employee’s credentials and/or session token(s) on a criminal underground market
• SMS phishing employee phone numbers with a link to a site configured with a fake login portal using an adversary-in-the-middle toolkit
• Using the employee’s pre-existing access to mobile telecommunications and business process outsourcing organizations to initiate a SIM swap or to set up call number forwarding on an employee’s phone number. Octo Tempest will initiate a self-service password reset of the user’s account once they have gained control of the employee’s phone number.

In rare instances, Octo Tempest resorts to fear-mongering tactics, targeting specific individuals through phone calls and texts. These actors use personal information, such as home addresses and family names, along with physical threats to coerce victims into sharing credentials for corporate access.

Reconnaissance and discovery 

Crossing borders for identity, architecture, and controls enumeration

In the early stage of their attacks, Octo Tempest performs various enumeration and information gathering actions to pursue advanced access in targeted environments and abuses legitimate channels for follow-on actions later in the attack sequence. Initial bulk-export of users, groups, and device information is closely followed by enumerating data and resources readily available to the user’s profile within virtual desktop infrastructure or enterprise-hosted resources. 

Frequently, Octo Tempest uses their access to carry out broad searches across knowledge repositories to identify documents related to network architecture, employee onboarding, remote access methods, password policies, and credential vaults.

Octo Tempest then performs exploration through multi-cloud environments enumerating access and resources across cloud environments, code repositories, server and backup management infrastructure, and others. In this stage, the threat actor validates access, enumerates databases and storage containers, and plans footholds to aid further phases of the attack.

Additional tradecraft and techniques:

• PingCastle and ADRecon to perform reconnaissance of Active Directory 
• Advanced IP Scanner to probe victim networks
• Govmomi Go library to enumerate vCenter APIs 
• PureStorage FlashArray PowerShell module to enumerate storage arrays 
• AAD bulk downloads of user, groups, and devices

Privilege escalation and credential access

Octo Tempest commonly elevates their privileges within an organization through the following techniques:

• Using their pre-existing access to mobile telecommunications and business process outsourcing organizations to initiate a SIM swap or to set up call number forwarding on an employee’s phone number. Octo Tempest will initiate a self-service password reset of the user’s account once they have gained control of the employee’s phone number.
• Social engineering – calling an organization’s help desk and socially engineering the help desk to reset an administrator’s password and/or change/add a multi-factor authentication token/factor

Further masquerading and collection for escalation

Octo Tempest employs an advanced social engineering strategy for privilege escalation, harnessing stolen password policy procedures, bulk downloads of user, group, and role exports, and their familiarity with the target organizations procedures. The actor’s privilege escalation tactics often rely on building trust through various means, such as leveraging possession of compromised accounts and demonstrating an understanding of the organization’s procedures. In some cases, they go as far as bypassing password reset procedures by using a compromised manager’s account to approve their requests.

Octo Tempest continually seeks to collect additional credentials across all planes of access. Using open-source tooling like Jercretz and TruffleHog, the threat actor automates the identification of plaintext keys, secrets, and credentials across code repositories for further use.

Additional tradecraft and techniques:

• Modifying access policies or using MicroBurst to gain access to credential stores
• Using open-source tooling: Mimikatz, Hekatomb, Lazagne, gosecretsdump, smbpasswd.py, LinPEAS, ADFSDump
• Using VMAccess Extension to reset passwords or modify configurations of Azure VMs
• Creating snapshots virtual domain controller disks to download and extract NTDS.dit
• Assignment of User Access Administrator role to grant Tenant Root Group management scope

Defense evasion

Security product arsenal sabotage

Octo Tempest compromises security personnel accounts within victim organizations to turn off security products and features and attempt to evade detection throughout their compromise. Using compromised accounts, the threat actor leverages EDR and device management technologies to allow malicious tooling, deploy RMM software, remove or impair security products, data theft of sensitive files (e.g. files with credentials, signal messaging databases, etc.), and deploy malicious payloads.

To prevent identification of security product manipulation and suppress alerts or notifications of changes, Octo Tempest modifies the security staff mailbox rules to automatically delete emails from vendors that may raise the target’s suspicion of their activities.

Additional tradecraft and techniques:

• Using open-source tooling like privacy.sexy framework to disable security products
• Enrolling actor-controlled devices into device management software to bypass controls
• Configuring trusted locations in Conditional Access Policies to expand access capabilities
• Replaying harvested tokens with satisfied MFA claims to bypass MFA

Persistence 

Sustained intrusion with identities and open-source tools

Octo Tempest leverages publicly available security tools to establish persistence within victim organizations, largely using account manipulation techniques and implants on hosts. For identity-based persistence, Octo Tempest targets federated identity providers using tools like AADInternals to federate existing domains, or spoof legitimate domains by adding and then federating new domains. The threat actor then abuses this federation to generate forged valid security assertion markup language (SAML) tokens for any user of the target tenant with claims that have MFA satisfied, a technique known as Golden SAML. Similar techniques have also been observed using Okta as their source of truth identity provider, leveraging Okta Org2Org functionality to impersonate any desired user account.

To maintain access to endpoints, Octo Tempest installs a wide array of legitimate RMM tools and makes required network modifications to enable access. The usage of reverse shells is seen across Octo Tempest intrusions on both Windows and Linux endpoints. These reverse shells commonly initiate connections to the same attacker infrastructure that deployed the RMM tools.

A unique technique Octo Tempest uses is compromising VMware ESXi infrastructure, installing the open-source Linux backdoor Bedevil, and then launching VMware Python scripts to run arbitrary commands against housed virtual machines.

Additional tradecraft and techniques:

• Usage of open-source tooling: ScreenConnect, FleetDeck, AnyDesk, RustDesk, Splashtop, Pulseway, TightVNC, LummaC2, Level.io, Mesh, TacticalRMM, Tailscale, Ngrok, WsTunnel, Rsocx, and Socat
• Deployment of Azure virtual machines to enable remote access via RMM installation or modification to existing resources via Azure serial console
• Addition of MFA methods to existing users
• Usage of the third-party tunneling tool Twingate, which leverages Azure Container instances as a private connector (without public network exposure)

Actions on objectives

Common trifecta: Data theft, extortion, and ransomware

The goal of Octo Tempest remains financially motivated, but the monetization techniques observed across industries vary between cryptocurrency theft and data exfiltration for extortion and ransomware deployment.

Like in most cyberattacks, data theft largely depends on the data readily available to the threat actor. Octo Tempest accesses data from code repositories, large document management and storage systems, including SharePoint, SQL databases, cloud storage blobs/buckets, and email, using legitimate management clients such as DBeaver, MongoDB Compass, Azure SQL Query Editor, and Cerebrata for the purpose of connection and collection. After data harvesting, the threat actor employs anonymous file-hosting services, including GoFile.io, shz.al, StorjShare, Temp.sh, MegaSync, Paste.ee, Backblaze, and AWS S3 buckets for data exfiltration.

Octo Tempest employs a unique technique using the data movement platform Azure Data Factory and automated pipelines to extract data to external actor hosted Secure File Transfer Protocol (SFTP) servers, aiming to blend in with typical big data operations. Additionally, the threat actor commonly registers legitimate Microsoft 365 backup solutions such as Veeam, AFI Backup, and CommVault to export the contents of SharePoint document libraries and expedite data exfiltration.

Ransomware deployment closely follows data theft objectives. This activity targets both Windows and Unix/Linux endpoints and VMware hypervisors using a variant of ALPHV/BlackCat. Encryption at the hypervisor level has shown significant impact to organizations, making recovery efforts difficult post-encryption.

Octo Tempest frequently communicates with target organizations and their personnel directly after encryption to negotiate or extort the ransom—providing “proof of life” through samples of exfiltrated data. Many of these communications have been leaked publicly, causing significant reputational damage to affected organizations.

Additional tradecraft and techniques:

• Use of the third-party services like FiveTran to extract copies of high-value service databases, such as SalesForce and ZenDesk, using API connectors
• Exfiltration of mailbox PST files and mail forwarding to external mailboxes

Recommendations

Hunting methodology

Octo Tempest’s utilization of social engineering, living-off-the land techniques, and diverse toolsets could make hunting slightly unorthodox. Following these general guidelines alongside robust deconfliction with legitimate users will surface their activity:

Identity

• Understand authentication flows in the environment.
• Centralize visibility of administrative changes in the environment into a single pane of glass.
• Scrutinize all user and sign-in risk detections for any administrator within the timeframe. Common alerts that are surfaced during an Octo Tempest intrusion include (but not limited to): Impossible Travel, Unfamiliar Sign-in Properties, and Anomalous Token
• Review the coverage of Conditional Access policies; scrutinize the use of trusted locations and exclusions.
• Review all existing and new custom domains in the tenant, and their federation settings.
• Scrutinize administrator groups, roles, and privileges for recent modification.
• Review recently created Microsoft Entra ID users and registered device identities.
• Look for any anomalous pivots into organizational apps that may hold sensitive data, such as Microsoft SharePoint and OneDrive.

Azure

• Leverage and continuously monitor Defender for Cloud for Azure Workloads, providing a wealth of information around unauthorized resource access.
• Review Azure role-based access control (RBAC) definitions across the management group, subscription, resource group and resource structure.
• Review the public network exposure of resources and revoke any unauthorized modifications.
• Review both data plane and management plane access control for all critical workloads such as those that hold credentials and organizational data, like Key Vaults, storage accounts, and database resources.
• Tightly control access to identity workloads that issue access organizational resources such as Active Directory Domain Controllers.
• Review the Azure Activity log for anomalous modification of resources.

Endpoints

• Look for recent additions to the indicators or exclusions of the EDR solution in place at the organization.
• Review any generation of offboarding scripts.
• Review access control within security products and EDR software suites.
• Scrutinize any tools used to manage endpoints (SCCM, Intune, etc.) and look for recent rule additions, packages, or deployments.
• Scrutinize use of remote administration tools across the environment, paying particular attention to recent installations regardless of whether they are used legitimately within the network already.
• Ensure monitoring at the network boundary is in place, that alerting is in place for connections with common anonymizing services and scrutinize the use of these services.

Defending against Octo Tempest activity

Align privilege in Microsoft Entra ID and Azure

Privileges spanning Microsoft Entra ID and Azure need to be holistically aligned, with purposeful design decisions to prevent unauthorized access to critical workloads. Reducing the number of users with permanently assigned critical roles is paramount to achieving this. Segregation of privilege between on-premises and cloud is also necessary to sever the ability to pivot within the environment.

It is highly recommended to implement Microsoft Entra Privileged Identity Management (PIM) as a central location for the management of both Microsoft Entra ID roles and Azure RBAC. For all critical roles, at minimum:

• Implement role assignments as eligible rather than permanent.
• Review and understand the role definition Actions and NotActions – ensure to select only the roles with actions that the user requires to do their role (least privileged access).
• Configure these roles to be time-bound, deactivating after a specific timeframe.
• Require users to perform MFA to elevate to the role.
• Optionally require users to provide justification or a ticket number upon elevation.
• Enable notifications for privileged role elevation to a subset of administrators.
• Utilize PIM Access Reviews to reduce standing access in the organization on a periodic basis.

Every organization is different and, therefore, roles will be classified differently in terms of their criticality. Consider the scope of impact those roles may have on downstream resources, services, or identities in the event of compromise. For help desk administrators specifically, ensure to scope privilege to exclude administrative operations over Global Administrators. Consider implementing segregation strategies such as Microsoft Entra ID Administrative Units to segment administrative access over the tenant. For identities that leverage cross-service roles such as those that service the Microsoft Security Stack, consider implementing additional service-based granular access control to restrict the use of sensitive functionality, like Live Response and modification of IOC allow lists.

Segment Azure landing zones

For organizations yet to begin or are early in their modernization journey, end-to-end guidance for cloud adoption is available through the Microsoft Azure Cloud Adoption Framework. Recommended practice and security are central pillars—Azure workloads are segregated into separate, tightly restricted areas known as landing zones. When deploying Active Directory in the cloud, it is advised to create a platform landing zone for identity—a dedicated subscription to hold all Identity-related resources such as Domain Controller VM resources. Employ least privilege across this landing zone with the aforementioned privilege and PIM guidance for Azure RBAC.

Implement Conditional Access policies and authentication methods

TTPs outlined in this blog leverage strategies to evade multifactor authentication defenses. However, it is still strongly recommended to practice basic security hygiene by implementing a baseline set of Conditional Access policies:

• Require multifactor authentication for all privileged roles with the use of authentication strengths to enforce phish-resistant MFA methods such as FIDO2 security keys
• Require phishing-resistant multifactor authentication for administrators
• Enforce MFA registration from trusted locations from a device that also meets organizational requirements with Intune device compliance policies
• User and sign-in risk policies for signals associated to Microsoft Entra ID Protection

Organizations are recommended to keep their policies as simple as possible. Implementing complex policies might inhibit the ability to respond to threats at a rapid pace or allow threat actors to leverage misconfigurations within the environment.

Develop and maintain a user education strategy

An organization’s ability to protect itself against cyberattacks is only as strong as its people—it is imperative to put in place an end-to-end cybersecurity strategy highlighting the importance of ongoing user education and awareness. Targeted education and periodic security awareness campaigns around common cyber threats and attack vectors such as phishing and social engineering not only for users that hold administrative privilege in the organization, but the wider user base is crucial. A well-maintained incident response plan should be developed and refined to enable organizations to respond to unexpected cybersecurity events and rapidly regain positive control.

Use out-of-band communication channels

Octo Tempest has been observed joining, recording, and transcribing calls using tools such as OtterAI, and sending messages via Slack, Zoom, and Microsoft Teams, taunting and threatening targets, organizations, defenders, and gaining insights into incident response operations/planning. Using out-of-band communication channels is strongly encouraged when dealing with this threat actor.

Detections

Microsoft 365 Defender

Microsoft 365 Defender is becoming Microsoft Defender XDR. Learn more.

NOTE: Several tools mentioned throughout this blog are remote administrator tools that have been utilized by Octo Tempest to maintain persistence. While these tools are abused by threat actors, they can have legitimate use cases by normal users, and are updated on a frequent basis. Microsoft recommends monitoring their use within the environment, and when they are identified, defenders take the necessary steps for deconfliction to verify their use.

Microsoft Defender Antivirus

Microsoft Defender Antivirus detects this threat as the following malware:

• HackTool:Win32/Mimikatz
• HackTool:Win64/Mimikatz
• Behavior:Win32/BlackCatExec
• Ransom:Win32/Blackcat
• Ransom:Linux/BlackCat
• Behavior:Win32/BlackCat
• Ransom:Win64/BlackCat

Turning on tamper protection, which is part of built-in protection, prevents attackers from stopping security services.

Microsoft Defender for Endpoint

The following Microsoft Defender for Endpoint alerts can indicate associated threat activity:

• Octo Tempest activity group

The following alerts might also indicate threat activity related to this threat. Note, however, that these alerts can also be triggered by unrelated threat activity.

• Suspicious usage of remote management software
• Mimikatz credential theft tool
• BlackCat ransomware
• Activity linked to BlackCat ransomware
• Tampering activity typical to ransomware attacks
• Possible hands-on-keyboard pre-ransom activity

Microsoft Defender for Cloud Apps

Using Microsoft Defender for Cloud Apps connectors, Microsoft 365 Defender raises AitM-related alerts in multiple scenarios. For Microsoft Entra ID customers using Microsoft Edge, attempts by attackers to replay session cookies to access cloud applications are detected by Microsoft 365 Defender through Defender for Cloud Apps connectors for Microsoft Office 365 and Azure. In such scenarios, Microsoft 365 Defender raises the following alerts:

• Backdoor creation using AADInternals tool
• Suspicious domain added to Microsoft Entra ID
• Suspicious domain trust modification following risky sign-in
• User compromised via a known AitM phishing kit
• User compromised in AiTM phishing attack
• Suspicious email deletion activity

Similarly, the connector for Okta raises the following alerts:

• Suspicious Okta account enumeration
• Possible AiTM phishing attempt in Okta

Microsoft Defender for Identity

Microsoft Defender for Identity raises the following alerts for TTPs used by Octo Tempest such as NTDS stealing and Active Directory reconnaissance:

• Account enumeration reconnaissance
• Network-mapping reconnaissance (DNS)
• User and IP address reconnaissance (SMB)
• User and Group membership reconnaissance (SAMR)
• Suspected DCSync attack (replication of directory services)
• Suspected AD FS DKM key read
• Data exfiltration over SMB

Microsoft Defender for Cloud

The following Microsoft Defender for Cloud alerts relate to TTPs used by Octo Tempest. Note, however, that these alerts can also be triggered by unrelated threat activity.

• MicroBurst exploitation toolkit used to enumerate resources in your subscriptions
• MicroBurst exploitation toolkit used to execute code on your virtual machine
• MicroBurst exploitation toolkit used to extract keys from your Azure key vaults
• MicroBurst exploitation toolkit used to extract keys to your storage accounts
• Suspicious Azure role assignment detected
• Suspicious elevate access operation (Preview)
• Suspicious invocation of a high-risk ‘Initial Access’ operation detected (Preview)
• Suspicious invocation of a high-risk ‘Credential Access’ operation detected (Preview)
• Suspicious invocation of a high-risk ‘Data Collection’ operation detected (Preview)
• Suspicious invocation of a high-risk ‘Execution’ operation detected (Preview)
• Suspicious invocation of a high-risk ‘Impact’ operation detected (Preview)
• Suspicious invocation of a high-risk ‘Lateral Movement’ operation detected (Preview)
• Unusual user password reset in your virtual machine
• Suspicious usage of VMAccess extension was detected on your virtual machines (Preview)
• Suspicious usage of multiple monitoring or data collection extensions was detected on your virtual machines (Preview)
• Run Command with a suspicious script was detected on your virtual machine (Preview)
• Suspicious Run Command usage was detected on your virtual machine (Preview)
• Suspicious unauthorized Run Command usage was detected on your virtual machine (Preview)

Microsoft Sentinel

Microsoft Sentinel customers can use the following Microsoft Sentinel Analytics template to identify potential AitM phishing attempts:

• Possible AitM Phishing Attempt Against Azure AD

This detection uses signals from Microsoft Entra ID Identity Protection and looks for successful sign-ins that have been flagged as high risk. It combines this with data from web proxy services, such as ZScaler, to identify where users might have connected to the source of those sign-ins immediately prior. This can indicate a user interacting with an AitM phishing site and having their session hijacked. This detection uses the Advanced Security Information Model (ASIM) Web Session schema. Refer to this article for more details on the schema and its requirements. 

Threat intelligence reports

Microsoft customers can use the following reports in Microsoft products to get the most up-to-date information about the threat actor, malicious activity, and techniques discussed in this blog. These reports provide the intelligence, protection info, and recommended actions to prevent, mitigate, or respond to associated threats found in customer environments.

Microsoft Defender Threat Intelligence

• Octo Tempest
• Octo Tempest uses social engineering and AADInternals to compromise cloud identities

Microsoft 365 Defender Threat analytics  

• Actor profile: Octo Tempest
• Threat insights: Octo Tempest uses social engineering and AADInternals to compromise cloud identities

Hunting queries

Microsoft Sentinel

Microsoft Sentinel customers can use the TI Mapping analytics (a series of analytics all prefixed with ‘TI map’) to automatically match the malicious domain indicators mentioned in this blog post with data in their workspace. If the TI Map analytics are not currently deployed, customers can install the Threat Intelligence solution from the Microsoft Sentinel Content Hub to have the analytics rule deployed in their Sentinel workspace.

Microsoft Sentinel also has a range of detection and threat hunting content that customers can use to detect the post exploitation activity detailed in this blog in addition to Microsoft 365 Defender detections list above.

• Suspicious sign-in followed by MFA modification
• Account MFA modifications
• Okta SSO phishing detection
• Okta rare MFA operations
• Okta login from different locations
• Okta user password reset
• SharePointFileOperation via clientIP with previously unseen user agents
• SharePointFileOperation via devices with previously unseen user agents
• SharePointFileOperation via previously unseen IPs of risky ASN’s
• SharePointFileOperation via previously unseen IPs
• Anomalous AAD account manipulation
• New external user granted admin
• Anomolous sign-ins based on time
• New account added to admin group
• Authentication methods changed for privileged account
• Rare run command PowerShell script
• Azure NSG administrative operations
• Rare operations of create and update of snapshots
• AdFind usage
• Anomalous listing of storage keys
• Storage account key enumeration
• Potential Microsoft Security services tampering
• Potential Microsoft Defender tampering
• Office mail forwarding
• Multiple users Office mail forwarding

Further reading

Listen to Microsoft experts discuss Octo Tempest TTPs and activities on The Microsoft Threat Intelligence Podcast.

Visit this page for more blogs from Microsoft Incident Response.

For more security research from the Microsoft Threat Intelligence community, check out the Microsoft Threat Intelligence Blog: https://aka.ms/threatintelblog.

To get notified about new publications and to join discussions on social media, follow us on X (formerly Twitter) at https://twitter.com/MsftSecIntel.

November 1, 2023 update: Updated the Actions of objectives section to fix the list of anonymous file-hosting services used by Octo Tempest for data exfiltration, which incorrectly listed Sh.Azl. It has been corrected to shz.al.

The post Octo Tempest crosses boundaries to facilitate extortion, encryption, and destruction appeared first on Microsoft Security Blog.

April 2023 update – Microsoft Threat Intelligence has shifted to a new threat actor naming taxonomy aligned around the theme of weather.

• BROMINE is now tracked as Ghost Blizzard
• DEV-0401 is now tracked as Cinnamon Tempest
• GALLIUM is now tracked as Granite Typhoon
• DEV-0062 is now tracked as Storm-0062
• ZINC is now tracked as Diamond Sleet

To learn about how the new taxonomy represents the origin, unique traits, and impact of threat actors, and to get a complete mapping of threat actor names, read this blog: Microsoft shifts to a new threat actor naming taxonomy.

At CyberWarCon 2022, Microsoft and LinkedIn analysts presented several sessions detailing analysis across multiple sets of actors and related activity. This blog is intended to summarize the content of the research covered in these presentations and demonstrates Microsoft Threat Intelligence Center’s (MSTIC) ongoing efforts to track threat actors, protect customers from the associated threats, and share intelligence with the security community.

The CyberWarCon sessions summarized below include:

• “They are still berserk: Recent activities of BROMINE” – a lightning talk covering MSTIC’s analysis of BROMINE (aka Berserk Bear), recent observed activities, and potential changes in targeting and tactics.
• “The phantom menace: A tale of Chinese nation-state hackers” – a deep dive into several of the Chinese nation-state actor sets, their operational security patterns, and case studies on related tactics, techniques, and procedures (TTPs).
• “ZINC weaponizing open-source software” – a lighting talk on MSTIC and LinkedIn’s analysis of ZINC, a North Korea-based actor. This will be their first public joint presentation, demonstrating collaboration between MSTIC and LinkedIn’s threat intelligence teams.

MSTIC consistently tracks threat actor activity, including the groups discussed in this blog, and works across Microsoft Security products and services to build detections and improve customer protections. As with any observed nation-state actor activity, Microsoft has directly notified customers that have been targeted or compromised, providing them with the information they need to help secure their accounts. Microsoft uses DEV-#### designations as a temporary name given to an unknown, emerging, or a developing cluster of threat activity, allowing MSTIC to track it as a unique set of information until we reach a high confidence about the origin or identity of the actor behind the activity. Once it meets the criteria, a DEV is converted to a named actor.

They are still berserk: Recent activities of BROMINE

BROMINE overlaps with the threat group publicly tracked as Berserk Bear. In our talk, MSTIC provided insights into the actor’s recent activities observed by Microsoft. Some of the recent activities presented include:

• Targeting and compromise of dissidents, political opponents, Russian citizens, and foreign diplomats. These activities have spanned multiple methods and techniques, ranging from the use of a custom malicious capability to credential phishing leveraging consumer mail platforms. In some cases, MSTIC has identified the abuse of Azure free trial subscriptions and worked with the Azure team to quickly take action against the abuse.
• Continued targeting of organizations in the manufacturing and industrial technology space. These sectors have been continuous targets of the group for years and represent one of the most durable interests.
• An opportunistic campaign focused on exploiting datacenter infrastructure management interfaces, likely for the purpose of access to technical information of value.
• Targeting and compromise of diplomatic sector organizations focused on personnel assigned to Eastern Europe.
• Compromise of a Ukrainian nuclear safety organization previously referenced in our June 2022 Special Report on Defending Ukraine (https://aka.ms/ukrainespecialreport).

Overall, our findings continue to demonstrate that BROMINE is an elusive threat actor with a variety of potential objectives, yet sporadic insights from various organizations, including Microsoft, demonstrate there is almost certainly more to find. Additionally, our observations show that as a technology platform provider, threat intelligence enables Microsoft’s ability to protect both enterprises and consumers and disrupt threat activity affecting our customers.

The phantom menace: A tale of China-based nation state hackers

Over the past few years, MSTIC has observed a gradual evolution of the TTPs employed by China-based threat actors. At CyberWarCon 2022, Microsoft analysts presented their analysis of these trends in Chinese nation-state actor activity, covering:

• Information about new tactics that these threat actors have adopted to improve their operational security, as well as a deeper look into their techniques, such as leveraging vulnerable SOHO devices for obfuscating their operations.
• Three different case studies, including China-based DEV-0401 and nation-state threat actors GALLIUM and DEV-0062, walking through (a) the initial vector (compromise of public-facing application servers, with the actors showing rapid adoption of proofs of concept for vulnerabilities in an array of products), (b) how these threat actors maintained persistence on the victims (some groups dropping web shells, backdoors, or custom malware), and (c) the objectives of their operations: intelligence collection for espionage.
• A threat landscape overview of the top five industries that these actors have targeted—governments worldwide, non-government organizations (NGO)s and think tanks, communication infrastructure, information technology (IT), and financial services – displaying the global nature of China’s cyber operations in the span of one year.

As demonstrated in the presentation, China-based threat actors have targeted entities nearly globally, employing techniques and using different methodologies to make attribution increasingly harder. Microsoft analysts assess that China’s cyber operations will continue to move along their geopolitical agenda, likely continuing to use some of the techniques mentioned in the presentation to conduct their intelligence collection. The graphic below illustrates how quickly we observe China-based threat actors and others exploiting zero-day vulnerabilities and then those exploits becoming broadly available in the wild.

ZINC weaponizing open-source software

In this talk, Microsoft and LinkedIn analysts detail recent activity of a North-Korea based nation-state threat actor we track as ZINC. Analysts detailed the findings of their investigation (previously covered in this blog) and walked through the series of observed ZINC attacks that targeted 125 different victims spanning 34 countries, noting the attacks appear to be motivated by traditional cyber-espionage and theft of personal and corporate data. A few highlights include:

• In September 2022, Microsoft disclosed detection of a wide range of social engineering campaigns using weaponized legitimate open-source software. MSTIC observed activity targeting employees in organizations across multiple industries including media, defense and aerospace, and IT services in the US, UK, India, and Russia.
• Based on the observed tradecraft, infrastructure, tooling, and account affiliations, MSTIC attributes this campaign with high confidence to ZINC, a state-sponsored group based out of North Korea with objectives focused on espionage, data theft, financial gain, and network destruction.
• When analyzing the data from an industry sector perspective, we observed that ZINC chose to deliver malware most likely to succeed in a specific environment, for example, targeting IT service providers with terminal tools and targeting media and defense companies with fake job offers to be loaded into weaponized PDF readers.
• ZINC has successfully compromised numerous organizations since June 2022, when the actor began employing traditional social engineering tactics by initially connecting with individuals on LinkedIn to establish a level of trust with their targets.
• Upon successful connection, ZINC encouraged continued communication over WhatsApp, which acted as the means of delivery for their malicious payloads. MSTIC observed ZINC weaponizing a wide range of open-source software including PuTTY, KiTTY, TightVNC, Sumatra PDF Reader, and muPDF/Subliminal Recording software installer for these attacks. ZINC was observed attempting to move laterally across victim networks and exfiltrate collected information from.

As the threat landscape continues to evolve, Microsoft strives to continuously improve security for all, through collaboration with customers and partners and by sharing our research with the larger security community. We would like to extend our thanks to CyberWarCon and LinkedIn for their community partnership.

The post Microsoft threat intelligence presented at CyberWarCon 2022  appeared first on Microsoft Security Blog.

• DEV-0206 is now tracked as Mustard Tempest
• DEV-0243 is now tracked as Manatee Tempest
• DEV-0950 is now tracked as Lace Tempest
• DEV-0651 is now tracked as Storm-0651
• DEV-0856 is now tracked as Storm-0856

To learn about how the new taxonomy represents the origin, unique traits, and impact of threat actors, and to get a complete mapping of threat actor names, read this blog: Microsoft shifts to a new threat actor naming taxonomy.

Microsoft has discovered recent activity indicating that the Raspberry Robin worm is part of a complex and interconnected malware ecosystem, with links to other malware families and alternate infection methods beyond its original USB drive spread. These infections lead to follow-on hands-on-keyboard attacks and human-operated ransomware activity. Our continuous tracking of Raspberry Robin-related activity also shows a very active operation: Microsoft Defender for Endpoint data indicates that nearly 3,000 devices in almost 1,000 organizations have seen at least one Raspberry Robin payload-related alert in the last 30 days.

Raspberry Robin has evolved from being a widely distributed worm with no observed post-infection actions when Red Canary first reported it in May 2022, to one of the largest malware distribution platforms currently active. In July 2022, Microsoft security researchers observed devices infected with Raspberry Robin being installed with the FakeUpdates malware, which led to DEV-0243 activity. DEV-0243, a ransomware-associated activity group that overlaps with actions tracked as EvilCorp by other vendors, was first observed deploying the LockBit ransomware as a service (RaaS) payload in November 2021. Since then, Raspberry Robin has also started deploying IcedID, Bumblebee, and Truebot based on our investigations.

In October 2022, Microsoft observed Raspberry Robin being used in post-compromise activity attributed to another actor, DEV-0950 (which overlaps with groups tracked publicly as FIN11/TA505). From a Raspberry Robin infection, the DEV-0950 activity led to Cobalt Strike hands-on-keyboard compromises, sometimes with a Truebot infection observed in between the Raspberry Robin and Cobalt Strike stage. The activity culminated in deployments of the Clop ransomware. DEV-0950 traditionally uses phishing to acquire the majority of their victims, so this notable shift to using Raspberry Robin enables them to deliver payloads to existing infections and move their campaigns more quickly to ransomware stages.

Given the interconnected nature of the cybercriminal economy, it’s possible that the actors behind these Raspberry Robin-related malware campaigns—usually distributed through other means like malicious ads or email—are paying the Raspberry Robin operators for malware installs.

Raspberry Robin attacks involve multi-stage intrusions, and its post-compromise activities require access to highly privileged credentials to cause widespread impact. Organizations can defend their networks from this threat by having security solutions like Microsoft Defender for Endpoint and Microsoft Defender Antivirus, which is built into Windows, to help detect Raspberry Robin and its follow-on activities, and by applying best practices related to credential hygiene, network segmentation, and attack surface reduction.

In this blog, we share our detailed analysis of these attacks and shed light on Raspberry Robin’s origins, since its earliest identified activity in September 2021, and motivations which have been debated since it was first reported in May 2022. We also provide mitigation guidance and other recommendations defenders can use to limit this malware’s spread and impact from follow-on hands-on-keyboard attacks.

A new worm hatches: Raspberry Robin’s initial propagation via USB drives

The Microsoft Detection and Response Team (DART) has been renamed to Microsoft Incident Response (Microsoft IR). For more information on IR services, go to Microsoft Incident Response

In early May 2022, Red Canary reported that a new worm named Raspberry Robin was spreading to Windows systems through infected USB drives. The USB drive contains a Windows shortcut (LNK) file disguised as a folder. In earlier infections, this file used a generic file name like recovery.lnk, but in more recent ones, it uses brands of USB drives. It should be noted that USB-worming malware isn’t new, and many organizations no longer track these as a top threat.  

For an attack relying on a USB drive to run malware upon insertion, the targeted system’s autorun.inf must be edited or configured to specify which code to start when the drive is plugged in. Autorun of removable media is disabled on Windows by default. However, many organizations have widely enabled it through legacy Group Policy changes.

There has been much public debate about whether the Raspberry Robin drives use autoruns to launch or if it relies purely on social engineering to encourage users to click the LNK file. Microsoft Threat Intelligence Center (MSTIC) and Microsoft Detection and Response Team (DART) research has confirmed that both instances exist in observed attacks. Some Raspberry Robin drives only have the LNK and executable files, while drives from earlier infections have a configured autorun.inf. This change could be linked to why the names of the shortcut files changed from more generic names to brand names of USB drives, possibly encouraging a user to execute the LNK file.

Upon insertion of the infected drive or launching of the LNK file, the UserAssist registry key in Windows—where Windows Explorer maintains a list of launched programs—is updated with a new value indicating a program was launched by Windows. 

The UserAssist key stores the names of launched programs in ROT13-ciphered format, which means that every letter in the name of the program is replaced with the 13^th letter in the alphabet after it. This routine makes the entries in this registry key not immediately readable. The UserAssist key is a useful forensic artifact to demonstrate which applications were launched on Windows, as outlined in Red Canary’s blog.

Windows shortcut files are mostly used to create an easy-to-find shortcut to launch a program, such as pinning a link to a user’s browser on the taskbar. However, the format allows the launching of any code, and attackers often use LNK files to launch malicious scripts or run stored code remotely. Raspberry Robin’s LNK file points to cmd.exe to launch the Windows Installer service msiexec.exe and install a malicious payload hosted on compromised QNAP network attached storage (NAS) devices.

Once the Raspberry Robin payload is running, it spawns additional processes by using system binaries such as rundll32.exe, odbcconf.exe, and control.exe to use as living-off-the-land binaries (LOLBins) to run malicious code. Raspberry Robin also launches code via fodhelper.exe, a system binary for managing optional features, as a user access control (UAC) bypass.

The malware injects into system processes including regsvr32.exe, rundll32.exe, and dllhost.exe and connects to various command-and-control (C2) servers hosted on Tor nodes.

In most instances, Raspberry Robin persists by adding itself to the RunOnce key of the registry hive associated with the user who executed the initial malware install. The registry key points to the Raspberry Robin binary, which has a random name and a random extension such as .mh or .vdm in the user’s AppData folder or to ProgramData. The key uses the intended purpose of regsvr32.exe to launch the portable executable (PE) file, allowing the randomized non-standard file extension to launch the executable content. 

Entries in the RunOnce key delete the registry entry prior to launching the executable content at sign-in. Raspberry Robin re-adds this key once it is successfully running to ensure persistence. After the initial infection, this leads to RunOnce.exe launching the malware payload in timelines. Raspberry Robin also temporarily renames the RunOnce key when writing to it to evade detections.

Raspberry Robin’s connection to a larger malware ecosystem

Since our initial analysis, Microsoft security researchers have discovered links between Raspberry Robin and other malware families. The Raspberry Robin implant has also started to distribute other malware families, which is not uncommon in the cybercriminal economy, where attackers purchase “loads” or installs from operators of successful and widespread malware to facilitate their goals.

Introducing Fauppod: Like FakeUpdates but without the fake updates

On July 26, 2022, Microsoft witnessed the first reported instance of a Raspberry Robin-infected host deploying a FakeUpdates (also known as SocGholish) JavaScript backdoor. Previously, FakeUpdates were delivered primarily through drive-by downloads or malicious ads masquerading as browser updates. Microsoft tracks the activity group behind FakeUpdates as DEV-0206 and the USB-based Raspberry Robin infection operators as DEV-0856.

After discovering Raspberry Robin-deployed FakeUpdates, Microsoft security researchers continued monitoring for other previously unidentified methodologies in FakeUpdates deployments. Research into the various malware families dropped by Raspberry Robin’s USB-delivered infections continued, and new signatures were created to track the various outer layers of packed malware under the family name Fauppod.

On July 27, 2022, Microsoft identified samples detected as Fauppod that have similar process trees with DLLs written by Raspberry Robin LNK infections in similar locations and using similar naming conventions. Their infection chains also dropped the FakeUpdates malware. However, the victim hosts where these samples were detected didn’t have the traditional infection vector of an LNK file launched from an infected USB drive, as detailed in Red Canary’s blog.

In this instance, Fauppod was delivered via codeload[.]github[.]com, a fraudulent and malicious repository created by a cybercriminal actor that Microsoft tracks as DEV-0651. The payload was delivered as a ZIP archive file containing another ZIP file, which then had a massive (700MB) Control Panel (CPL) file inside. Attackers use nested containers such as ZIP, RAR, and ISO files to avoid having their malicious payloads stamped with Mark of the Web (MOTW), which Windows uses to mark files from the internet and thus enable security solutions to block certain actions. Control Panel files are similar to other PEs like EXE and DLL files.

Microsoft has since seen DEV-0651 deliver Fauppod samples by taking advantage of various public-facing trusted and legitimate cloud services beyond GitHub, including Azure, Discord, and SpiderOak. Refer to the indicators of compromise (IOCs) below for more details. Microsoft has shared information about this threat activity and service abuse with these hosting providers.

Connecting the dot(net malware)

With the discovery of the DEV-0651 link, Microsoft had two pieces of evidence suggesting a relationship between Fauppod and Raspberry Robin:

• Both malware families were delivering FakeUpdates
• Signatures created to detect Raspberry Robin DLL samples on hosts infected by the publicly known LNK file spreading mechanism were detecting malware that wasn’t being delivered through any previously known Raspberry Robin connections

Following DEV-0651’s previous leveraging of cloud hosting services, the earliest iteration of a DEV-0651-related campaign that Microsoft was able to identify occurred in September 2021, which was around the same time Red Canary stated Raspberry Robin began to propagate.

Based on these facts, Microsoft reached low-confidence assessment that the Fauppod malware samples were related to the later delivery of what was publicly known as Raspberry Robin and started investigating these links to raise confidence and discover more information.

While authoring both file-based and behavior-based detections for Fauppod samples, Microsoft utilized existing detections based on the use of OBDCCONF as a LOLBin to launch regsvr32 (which was also detailed in Red Canary’s blog as a Raspberry Robin tactic, technique, and procedure (TTP)):

Microsoft noted a unique quality in the command execution that was persistent through all Raspberry Robin infections stemming from an infected USB drive: there was a trailing “.” character at the end of the DLL name within the command above.

While reviewing DEV-0651 Fauppod-delivered malware, Microsoft identified a Fauppod CPL sample served via GitHub when the following command is run:

Notable in the above Fauppod command are the following:

• The use of msiexec.exe to launch the Windows binary shell32.dll as a LOLBin, instead of launching the malware PE directly via rundll32.exe, using rundll32.exe to launch shell32.dll, and passing ShellExec_RunDLL to load the commands—a TTP consistent with Raspberry Robin.
• Fauppod CPL file’s use of a staging directory to copy a payload to disk using randomly generated directories in ProgramData that then contain malicious PE files with randomly generated names and extensions. This naming pattern overlaps with those leveraged by publicly known Raspberry Robin DLLs.
• The same trailing “.” in the DLL name as seen in the ODBCCONF proxying detailed in Red Canary’s blog. Avast also later noted this trailing in the DLL implant dropped by Raspberry Robin, which they refer to as Roshtyak.

These findings raised Microsoft’s confidence in assessing whether there is a connection between Fauppod’s CPL files and Raspberry Robin extending beyond a similarity in outer layers and packing of the malware.

Microsoft security researchers also identified a payload within a Fauppod sample communicating with a compromised QNAP storage server to send information about the infected device, overlapping with Raspberry Robin’s use of compromised QNAP appliances for C2.

While continuing to monitor the prevalence and infection sources of Fauppod, Microsoft identified a heavily obfuscated .NET malware (SHA-256: a9d5ec72fad42a197cbadcb1edc6811e3a8dd8c674df473fd8fa952ba0a23c15) arriving on hosts that had previously been infected with either Raspberry Robin LNK infected hosts or Fauppod CPL malware.

While inspecting these samples, Microsoft noted that many were responsible for creating LNK files on external USB drives.

Based on our investigation, Microsoft currently assesses with medium confidence that the above .NET DLLs delivered both by Raspberry Robin LNK infections and Fauppod CPL samples are responsible for spreading Raspberry Robin LNK files to USB drives. These LNK files, in turn, infect other hosts via the infection chain detailed in Red Canary’s blog.

Microsoft also assesses with medium confidence that the Fauppod-packed CPL samples are currently the earliest known point in the attack chain for propagating Raspberry Robin infections to targets. Microsoft findings suggest that the Fauppod CPL entities, the obfuscated .NET LNK spreader modules they drop, the Raspberry Robin LNK files Red Canary documented, and the Raspberry Robin DLL files (or, Roshtyak, as per Avast) could all be considered as various components to the “Raspberry Robin” malware infection chain.

The Fauppod-Dridex connection

In July 2022, Microsoft found Raspberry Robin infections that led to hands-on-keyboard activity by DEV-0243. One of the earliest malware campaigns to bring notoriety to DEV-0243 was the Dridex banking trojan.

Code similarity between malware families is often used to demonstrate a link between families to a tracked actor. In IBM’s blog post published after we observed the Raspberry Robin and DEV-0243 connection, they highlighted several code similarities between the loader for the Raspberry Robin DLLs and the Dridex malware.

Microsoft’s analysis of Fauppod samples also identified some Dridex filename testing features, which are used to avoid running in certain environments. Fauppod has similar functionality to avoid execution if it recognizes it’s running as testapp.exe or self.exe. This code similarity has historically caused some Fauppod samples to trip Dridex detection alerts.

Given the previously documented relationship between Raspberry Robin and DEV-0206/DEV-0243 (EvilCorp), this behavioral similarity in the initial vector for Raspberry Robin infections adds another piece of evidence to the connection between the development and propagation of Fauppod/Raspberry Robin and DEV-0206/DEV-0243.

Raspberry Robin’s future as part of the cybercriminal gig economy

Cybercriminal malware is an ever-present threat for most organizations today, taking advantage of common weaknesses in security strategies and using social engineering to trick users. Almost every organization risks encountering these threats, including Fauppod/Raspberry Robin and FakeUpdates. Developing a robust protection and detection strategy and investing in credential hygiene, least privileges, and network segmentation are keys to preventing the impact of these complex and highly connected cybercriminal threats.

Raspberry Robin’s infection chain is a confusing and complicated map of multiple infection points that can lead to many different outcomes, even in scenarios where two hosts are infected simultaneously. There are numerous components involved; differentiating them could be challenging as the attackers behind the threat have gone to extreme lengths to protect the malware at each stage with complex loading mechanisms. These attackers also hand off to other actors for some of the more impactful attack stages, such as ransomware deployment.

As of this writing, Microsoft is aware of at least four confirmed Raspberry Robin entry vectors. These entry points were linked to hands-on-keyboard actions by attackers, and they all led to intrusions where the end goal was likely deployment of ransomware.

Infections from Fauppod CPL files and the Raspberry Robin worm component have facilitated human-operated intrusions indicative of pre-ransomware activity. Based on the multiple infection stages and varied payloads, Microsoft assesses that DEV-0651’s initial access vector, the various spreading techniques of the malicious components, and high infection numbers have provided an attractive distribution option for follow-on payloads.

Beginning on September 19, 2022, Microsoft identified Raspberry Robin worm infections deploying IcedID and—later at other victims—Bumblebee and TrueBot payloads. In October 2022, Microsoft researchers observed Raspberry Robin infections followed by Cobalt Strike activity from DEV-0950. This activity, which in some cases included a Truebot infection, eventually deployed the Clop ransomware.

Defending against Raspberry Robin infections

Worms can be noisy and could lead to alert fatigue in security operations centers (SOCs). Such fatigue could lead to improper or untimely remediation, providing the worm operator ample opportunity to sell access to the affected network to other cybercriminals.

While Raspberry Robin seemed to have no purpose when it was first discovered, it has evolved and is heading towards providing a potentially devastating impact on environments where it’s still installed. Raspberry Robin will likely continue to develop and lead to more malware distribution and cybercriminal activity group relationships as its install footprint grows.

Microsoft Defender for Endpoint and Microsoft Defender Antivirus detect Raspberry Robin and follow-on activities described in this blog. Defenders can also apply the following mitigations to reduce the impact of this threat:

• Prevent drives from using autorun and execution code on insertion or mount. This can be done via registry settings or Group Policy.
• Follow the defending against ransomware guidance in Microsoft’s RaaS blog post
• Enable tamper protection to prevent attacks from stopping or interfering with Microsoft Defender Antivirus.
• Turn on cloud-delivered protection in Microsoft Defender Antivirus or the equivalent for your antivirus product to cover rapidly evolving attacker tools and techniques. Cloud-based machine learning protections block a huge majority of new and unknown variants.

Microsoft customers can turn on attack surface reduction rules to prevent several of the infection vectors of this threat. Attack surface reduction rules, which any security administrator can configure, offer significant hardening against the worm. In observed attacks, Microsoft customers who had the following rules enabled were able to mitigate the attack in the initial stages and prevent hands-on-keyboard activity:

• Block untrusted and unsigned processes that run from USB
• Block execution of potentially obfuscated scripts
• Block executable files from running unless they meet a prevalence, age, or trusted list criterion
• Block credential stealing from the Windows local security authority subsystem (lsass.exe)

Defenders can also refer to detection details and indicators or compromise in the following sections for more information about surfacing this threat.

Detection details

Microsoft Defender Antivirus

Microsoft Defender Antivirus detects threat components as the following malware:

• Trojan:Win32/Fauppod

Configure Defender Antivirus scans to include removable drives. The following command lets admins scan removable drives, such as flash drives, during a full scan using the Set-MpPreference cmdlet:

Set-MpPreference -DisableRemovableDriveScanning

If you specify a value of $False or do not specify a value, Defender Antivirus scans removable drives during any type of scan. If you specify a value of $True, Defender Antivirus doesn’t scan removable drives during a full scan. Defender Antivirus can still scan removable drives during quick scans or custom scans.

Defender Antivirus also detects identified post-compromise payloads as the following malware:

• Behavior:Win32/Socgolsh.SB
• Trojan:JS/Socgolsh.A
• Trojan:JS/FakeUpdate.C
• Trojan:JS/FakeUpdate.B
• Trojan:Win32/IcedId
• Backdoor:Win32/Truebot
• TrojanDownloader:Win32/Truebot
• Trojan:Win32/Truebot
• Trojan:Win32/Bumblebee.E

Microsoft Defender for Endpoint

Alerts with the following titles in the security center can indicate threat activity on your network:

• Potential Raspberry Robin worm command
• Possible Raspberry Robin worm activity

Microsoft also clusters indicators related to the presence of the Raspberry Robin worm under DEV-0856. The following alert can indicate threat activity on your network:

• DEV-0856 activity group

The following alerts might also indicate threat activity associated with this threat. These alerts, however, can be triggered by unrelated threat activity and therefore are not monitored in the status cards provided with this report.

• Suspicious process launched using cmd.exe
• Suspicious behavior by msiexec.exe
• Observed BumbleBee malware activity
• Malware activity resembling Bumblebee loader detected
• BumbleBeeLoader malware was prevented
• Ransomware-linked emerging threat activity group detected
• Ongoing hands-on-keyboard attacker activity detected (Cobalt Strike)
• SocGholish command-and-control
• Suspicious ‘Socgolsh’ behavior was blocked
• DEV-0651 threat group activity associated with FakeUpdates JavaScript backdoor

Indicators of compromise (IOCs)

NOTE: These indicators should not be considered exhaustive for this observed activity.

Fauppod samples delivered by DEV-0651 via legitimate cloud services

Timeline of Raspberry Robin deployments of various payloads

The post Raspberry Robin worm part of larger ecosystem facilitating pre-ransomware activity appeared first on Microsoft Security Blog.

To learn about how the new taxonomy represents the origin, unique traits, and impact of threat actors, and to get a complete mapping of threat actor names, read this blog: Microsoft shifts to a new threat actor naming taxonomy.

In recent months, Microsoft has detected active ransomware and extortion campaigns impacting the global education sector, particularly in the US, by a threat actor we track as DEV-0832, also known as Vice Society. Shifting ransomware payloads over time from BlackCat, QuantumLocker, and Zeppelin, DEV-0832’s latest payload is a Zeppelin variant that includes Vice Society-specific file extensions, such as .v-s0ciety, .v-society, and, most recently, .locked. In several cases, Microsoft assesses that the group did not deploy ransomware and instead possibly performed extortion using only exfiltrated stolen data.

DEV-0832 is a cybercriminal group that has reportedly been active as early as June 2021. While the latest attacks between July and October 2022 have heavily impacted the education sector, DEV-0832’s previous opportunistic attacks have affected various industries like local government and retail. Microsoft assesses that the group is financially motivated and continues to focus on organizations where there are weaker security controls and a higher likelihood of compromise and ransom payout. Before deploying ransomware, DEV-0832 relies on tactics, techniques, and procedures commonly used among other ransomware actors, including the use of PowerShell scripts, repurposed legitimate tools, exploits for publicly disclosed vulnerabilities for initial access and post-compromise elevation of privilege, and commodity backdoors like SystemBC.

Ransomware has evolved into a complex threat that’s human-operated, adaptive, and focused on a wider scale, using data extortion as a monetization strategy to become even more impactful in recent years. To find easy entry and privilege escalation points in an environment, these attackers often take advantage of poor credential hygiene and legacy configurations or misconfigurations. Defenders can build a robust defense against ransomware by reading our ransomware as a service blog.

In this blog, we detail Microsoft’s analysis of observed DEV-0832 activity, including the tactics and techniques used across the group’s campaigns, with the goal of helping customers identify, investigate, and remediate activity in their environments. We provide hunting queries to help customers comprehensively search their environments for relevant indicators as well as protection and hardening guidance to help organizations increase resilience against these and similar attacks.

Who is DEV-0832 (Vice Society)?

Microsoft has identified multiple campaigns attributed to DEV-0832 over the past year based on the use of a unique PowerShell file name, staging directories, and ransom payloads and their accompanying notes. To gain an initial foothold in compromised networks, DEV-0832 has reportedly exploited vulnerable web-facing applications and used valid accounts. However, due to limited initial signals from affected organizations, Microsoft has not confirmed these attack vectors. Attackers then use custom PowerShell scripts, commodity tools, exploits for disclosed vulnerabilities, and native Windows binaries to gather privileged credentials, move laterally, collect and exfiltrate data, and deploy ransomware.

After deploying ransomware, DEV-0832 demands a ransom payment, threatening to leak stolen data on the group’s [.]onion site. In some cases, Microsoft observed that DEV-0832 did not deploy ransomware. Instead, the actors appeared to exfiltrate data and dwell within compromised networks. The group sometimes avoids a ransomware payload in favor of simple extortion—threatening to release stolen data unless a payment is made.

The group also goes to significant measures to ensure that an organization cannot recover from the attack without paying the ransom: Microsoft has observed DEV-0832 access two domain administrator accounts and reset user passwords of over 150,000 users, essentially locking out legitimate users before deploying ransomware to some devices. This effectively interrupts remediation efforts, including attempts to prevent the ransomware payload or post-compromise incident response.

Toolset

Ransomware payloads

Microsoft has observed DEV-0832 deploy multiple commodity ransomware variants over the past year: BlackCat, QuantumLocker, Zeppelin, and most recently a Vice Society-branded variant of the Zeppelin ransomware. While many ransomware groups have shifted away from branded file extensions in favor of randomly generated ones, DEV-0832 incorporated branding with their Vice Society variant using .v-s0ciety or .v-society file extensions. Most recently in late September 2022, DEV-0832 again modified their ransomware payload to a variant dubbed RedAlert, using a .locked file extension.

In one July 2022 intrusion, Microsoft security researchers identified DEV-0832 attempt to deploy QuantumLocker binaries, then within five hours, attempt to deploy suspected Zeppelin ransomware binaries. Such an incident might suggest that DEV-0832 maintains multiple ransomware payloads and switches depending on target defenses or, alternatively, that dispersed operators working under the DEV-0832 umbrella might maintain their own preferred ransomware payloads for distribution. The shift from a ransomware as a service (RaaS) offering (BlackCat) to a purchased wholly-owned malware offering (Zeppelin) and a custom Vice Society variant indicates DEV-0832 has active ties in the cybercriminal economy and has been testing ransomware payload efficacy or post-ransomware extortion opportunities.

In many intrusions, DEV-0832 stages their ransomware payloads in a hidden share on a Windows system, for example accessed via a share name containing “$”. Once DEV-0832 has exfiltrated data, they then distribute the ransomware onto local devices for launching, likely using group policy, as shown in the below command:

The group also has cross-platform capabilities: Microsoft identified the deployment of a Vice Society Linux Encryptor on a Linux ESXi server.

PowerShell scripts

DEV-0832 uses a PowerShell script to conduct a variety of malicious activities and make system-related changes within compromised networks. Like their ransomware payloads, DEV-0832 typically stages their PowerShell scripts on a domain controller.

Microsoft security researchers have observed several variations among identified DEV-0832 PowerShell scripts, indicating ongoing refinement and development over time—while some only perform system discovery commands, other scripts are further modified to perform persistence, defense evasion, data exfiltration, and even distribute the ransomware payloads.

Commodity tools

According to Microsoft investigations, DEV-0832 has used two commodity backdoors in ransomware attacks: SystemBC and PortStarter.

SystemBC is a post-compromise commodity remote access trojan (RAT) and proxy tool that has been incorporated into multiple diverse ransomware attacks. In one DEV-0832 intrusion, the attacker used both a compromised domain admin user account and a compromised contractor account to launch a PowerShell command that launched a SystemBC session under the value name “socks”:

PortStarter is a backdoor written in Go. According to Microsoft analysis, this malware provides functionality such as modifying firewall settings and opening ports to connect to pre-configured command-and-control (C2) servers.

DEV-0832 has also deployed ransomware payloads using the remote launching tool Power Admin. Power Admin is a legitimate tool that provides functionality to monitor servers and applications, as well as file access auditing. If an organization has enabled Console Security settings within Power Admin, an attacker must have credentials to make authorized changes.

Other commodity tools identified in DEV-0832 attacks include Advanced Port Scanner and Advanced IP Scanner for network discovery.

Abuse of legitimate tooling

Like many other ransomware actors, DEV-0832 relies on misusing legitimate system tools to reduce the need to launch malware or malicious scripts that automated security solutions might detect. Observed tools include:

• Use of the Windows Management Instrumentation Command-line (WMIC) to launch commands that delete Mongo databases, other backups, and security programs.
• Use of Impacket’s WMIexec functionality, an open-source tool to launch commands via WMI, and Impacket atexec.py, which launches commands using Task Scheduler.
• Use of the vssadmin command to delete shadow copy backups on Windows Server.
• Use of PsExec to remotely launch PowerShell, batch scripts, and deploy ransomware payloads

Additionally, in one identified intrusion, DEV-0832 attempted to turn off Microsoft Defender Antivirus using registry commands. Enabling Microsoft Defender Antivirus tamper protection helps block this type of activity.

Harvesting privileged credentials for ransomware deployment

Like other ransomware groups, after gaining an initial foothold within a network, DEV-0832 moves quickly to gather valid administrator local or domain credentials to ensure they can distribute ransomware payloads throughout the network for maximum impact.

Credential dumps

While Microsoft has not identified all the credential access techniques of DEV-0832, in many instances DEV-0832 accesses Local Security Authority Server Service (LSASS) dumps to obtain valid account credentials that were present in memory. Microsoft also observed that, instead of using a tool like Mimikatz to access a credential dump, DEV-0832 typically abuses the tool comsvcs.dll along with MiniDump to dump the LSASS process memory. Other ransomware actors have been observed using the same technique.

In cases where DEV-0832 obtained domain-level administrator accounts, they accessed NTDS dumps for later cracking. The following command shows the attacker exfiltrating the NTDS.dit file, which stores Active Directory data to an actor-created directory:

Kerberoast

Microsoft has also identified DEV-0832 used the malicious PowerSploit module Invoke-Kerberoast to perform a Kerberoast attack, which is a post-exploitation technique used to obtain credentials for a service account from Active Directory Domain Services (AD DS). The Invoke-Kerberoast module requests encrypted service tickets and returns them in an attacker-specified output format compatible with cracking tools. The group can use the cracked Kerberos hashes to reveal passwords for service accounts, often providing access to an account that has the equivalent of domain admin privileges. Furthermore, one Kerberos service ticket can have many associated service principal names (SPNs); successful Kerberoasting can then grant an attacker access to the SPNs’ associated service or user accounts, such as obtaining ticket granting service (TGS) tickets for Active Directory SPNs that would allow an attacker to do offline password cracking.

Combined with the fact that service account passwords are not usually set to expire and typically remain unchanged for a great length of time, attackers like DEV-0832 continue to rely on Kerberoasting in compromised networks. Microsoft 365 Defender blocks this attack with Antimalware Scan Interface (AMSI) and machine learning. Monitor for alerts that reference Kerberoast attacks closely as the presence of these alerts typically indicates a human adversary in your environment.

Account creation

In one suspected DEV-0832 intrusion, Microsoft observed an operator create accounts that, based on the naming convention, were designed to blend in as admin accounts and allow persistence without malware, as shown in the following command:

Monitoring newly created accounts can help identify this type of suspicious activity that does not rely on launching malware for persistence in the environment.

Exploitation of privilege escalation vulnerabilities

In August 2022, Microsoft security researchers identified one file during a DEV-0832 intrusion indicating that the group has incorporated an exploit for the disclosed, patched security flaw CVE-2022-24521 (Windows Common Log File System (CLFS) logical-error vulnerability). Microsoft released a patch in April 2022. The DEV-0832 file spawns a new cmd.exe process with system privileges.

According to public reporting, DEV-0832 has also incorporated exploits for the PrintNightmare vulnerability to escalate privileges in a domain. Combined with the CVE-2022-24521 exploit code, it is likely that DEV-0832, like many other adversaries, quickly incorporates available exploit code for disclosed vulnerabilities into their toolset to target unpatched systems.

Lateral movement with valid accounts

After gaining credentials, DEV-0832 frequently moves laterally within a network using Remote Desktop Protocol (RDP). And as previously mentioned, DEV-0832 has also used valid credentials to interact with remote network shares over Server Message Block (SMB) where they stage ransomware payloads and PowerShell scripts.

Data exfiltration

In one known intrusion, DEV-0832 operators exfiltrated hundreds of gigabytes of data by launching their PowerShell script, which was staged on a network share. The script contained hardcoded attacker-owned IP addresses and searched for wide-ranging, non-targeted keywords ranging from financial documents to medical information, while excluding files containing keywords such as varied antivirus product names or file artifact extensions. Given the wide range of keywords included in the script, it is unlikely that DEV-0832 regularly customizes it for each target.

Microsoft suspects that DEV-0832 uses legitimate tools Rclone and MegaSync for data exfiltration as well; many ransomware actors leverage these tools, which provide capabilities to upload files to cloud storage. DEV-0832 also uses file compression tools to collect data from compromised devices.

Mitigations

Apply these mitigations to reduce the impact of this threat:

• Use device discovery to increase your visibility into your network by finding unmanaged devices on your network and onboarding them to Microsoft Defender for Endpoint.
• Use Microsoft Defender Vulnerability Management to assess your current status and deploy any updates that might have been missed.
• Utilize Microsoft Defender Firewall, intrusion prevention devices, and your network firewall to prevent RPC and SMB communication among endpoints whenever possible. This limits lateral movement as well as other attack activities.
• Turn on cloud-delivered protection in Microsoft Defender Antivirus or the equivalent for your antivirus product to cover rapidly evolving attacker tools and techniques. Cloud-based machine learning protections block a huge majority of new and unknown variants.
• Turn on tamper protection features to prevent attackers from stopping security services.
• Run endpoint detection and response (EDR) in block mode so that Microsoft Defender for Endpoint can block malicious artifacts, even when your non-Microsoft antivirus doesn’t detect the threat or when Microsoft Defender Antivirus is running in passive mode. EDR in block mode works behind the scenes to remediate malicious artifacts that are detected post-breach.
• Enable investigation and remediation in full automated mode to allow Microsoft Defender for Endpoint to take immediate action on alerts to resolve breaches, significantly reducing alert volume.
• LSA protection is enabled by default on new Windows 11 devices, hardening the platform against credential dumping techniques. LSA PPL protection will further restrict access to memory dumps making it hard to obtain credentials.
• Refer to Microsoft’s blog Ransomware as a service: Understanding the cybercrime gig economy and how to protect yourself for recommendations on building strong credential hygiene and other robust measures to defend against ransomware.

Microsoft customers can turn on attack surface reduction rules to prevent several of the infection vectors of this threat. These rules, which can be configured by any administrator, offer significant hardening against ransomware attacks. In observed attacks, Microsoft customers who had the following rules enabled were able to mitigate the attack in the initial stages and prevented hands-on-keyboard activity:

• Block process creations originating from PsExec and WMI commands
• Block executable files from running unless they meet a prevalence, age, or trusted list criterion
• Use advanced protection against ransomware
• Block credential stealing from the Windows local security authority subsystem (lsass.exe)

Detection details

Microsoft Defender Antivirus

Microsoft Defender Antivirus detects DEV-0832’s Vice Society-branded Zeppelin variant as the following malware:

• Ransom:Win32/VSocCrypt
• Trojan:PowerShell/VSocCrypt
• Ransom:Linux/ViceSociety

Other commodity ransomware variants previously leveraged by DEV-0832 are detected as:

• Behavior:Win32/Ransomware!Quantum.A
• Behavior:Win32/Quantum.AA
• Ransom:Win32/Zeppelin
• Ransom:Win32/Blackcat

SystemBC and PortStarter are detected as:

• Behavior:Win32/SystemBC
• Trojan:Win32/SystemBC
• Backdoor:Win64/PortStarter

Some pre-ransomware intrusion activity used in multiple campaigns by various activity groups can be detected generically. During identified DEV-0832 activity, associated command line activity was detected with generic detections, including:

• Behavior:Win32/OfficeInjectingProc.A
• Behavior:Win32/PsexecRemote.E
• Behavior:Win32/SuspRemoteCopy.B
• Behavior:Win32/PSCodeInjector.A
• Behavior:Win32/REnamedPowerShell.A

Microsoft Defender for Endpoint

The following Microsoft Defender for Endpoint alerts can indicate threat activity on your network:

• DEV-0832 activity group
• ‘VSocCrypt’ ransomware was prevented

The following alerts might also indicate threat activity associated with this threat. These alerts, however, can be triggered by unrelated threat activity.

• Use of living-off-the-land binary to run malicious code
• Potential SystemBC execution via Windows Task Scheduler
• Suspicious sequence of exploration activities
• Process memory dump
• Suspicious behavior by cmd.exe was observed
• Suspicious remote activity
• Suspicious access to LSASS service
• Suspicious credential dump from NTDS.dit
• File backups were deleted
• System recovery setting tampering

The post DEV-0832 (Vice Society) opportunistic ransomware campaigns impacting US education sector appeared first on Microsoft Security Blog.

To learn about how the new taxonomy represents the origin, unique traits, and impact of threat actors, and to get a complete mapping of threat actor names, read this blog: Microsoft shifts to a new threat actor naming taxonomy.

Hive ransomware is only about one year old, having been first observed in June 2021, but it has grown into one of the most prevalent ransomware payloads in the ransomware as a service (RaaS) ecosystem. With its latest variant carrying several major upgrades, Hive also proves it’s one of the fastest evolving ransomware families, exemplifying the continuously changing ransomware ecosystem.

The upgrades in the latest variant are effectively an overhaul: the most notable changes include a full code migration to another programming language and the use of a more complex encryption method. The impact of these updates is far-reaching, considering that Hive is a RaaS payload that Microsoft has observed in attacks against organizations in the healthcare and software industries by large ransomware affiliates like DEV-0237.

Microsoft Threat Intelligence Center (MSTIC) discovered the new variant while analyzing detected Hive ransomware techniques for dropping .key files. We know that Hive drops its encryption keys file, which contains encrypted keys used to decrypt encrypted files, and uses a consistent naming pattern:

[KEY_NAME].key.[VICTIM_IDENTIFIER] 
(e.g., BiKtPupMjgyESaene0Ge5d0231uiKq1PFMFUEBNhAYv_.key.ab123)

The said .key files were missing the [VICTIM_IDENTIFIER] part of the file name, prompting deeper analysis of the Hive ransomware that dropped them. This analysis led to the discovery of the new Hive variant and its multiple versions, which exhibit slightly different available parameters in the command line and the executed processes.

Analyzing these patterns in samples of the new variants, we discovered even more samples, all with a low detection rate and none being correctly identified as Hive. In this blog we will share our in-depth analysis of the new Hive variant, including its main features and upgrades, with the aim of equipping analysts and defenders with information to better identify and protect organizations against malware attacks relying on Hive.

Analysis and key findings

The switch from GoLang to Rust

The main difference between the new Hive variant and old ones is the programming language used. The old variants were written in Go (also referred to as GoLang), while the new Hive variant is written in Rust.

Hive isn’t the first ransomware written in Rust—BlackCat, another prevalent ransomware, was the first. By switching the underlying code to Rust, Hive benefits from the following advantages that Rust has over other programming languages:

• It offers memory, data type, and thread safety
• It has deep control over low-level resources
• It has a user-friendly syntax
• It has several mechanisms for concurrency and parallelism, thus enabling fast and safe file encryption
• It has a good variety of cryptographic libraries
• It’s relatively more difficult to reverse-engineer

String encryption

The new Hive variant uses string encryption that can make it more evasive. Strings reside in the .rdata section and are decrypted during runtime by XORing with constants. The constants that are used to decrypt the same string sometimes differ across samples, making them an unreliable basis for detection.

For example, let’s look at the section where part of the string “!error no flag -u <login>:<password> provided” is decrypted. In one sample (SHA-256: f4a39820dbff47fa1b68f83f575bc98ed33858b02341c5c0464a49be4e6c76d3), the constants are 0x9F2E3F1F and 0x95C9:

In another sample (SHA-256: 6e5d49f604730ef4c05cfe3f64a7790242e71b4ecf1dc5109d32e811acf0b053), the constants are 0x3ECF7CC4 and 0x198F:        

Some samples do share constants when decrypting the same string. For example, let’s look where the parameter string “-da” is decrypted. In one sample (SHA-256: 88b1d8a85bf9101bc336b01b9af4345ed91d3ec761554d167fe59f73af73f037), the constants are 0x71B4 and 2:

In another sample (SHA-256: 33744c420884adf582c46a4b74cbd9c145f2e15a036bb1e557e89d6fd428e724), the constants are the same:

Command-line parameters

In old Hive variants, the username and the password used to access the Hive ransom payment website are embedded in the samples. In the new variant, these credentials must be supplied in the command line under the “-u” parameter, which means that they can’t be obtained by analysts from the sample itself.

Like most modern ransomware, Hive introduces command-line parameters, which allow attackers flexibility when running the payload by adding or removing functionality. For example, an attacker can choose to encrypt files on remote shares or local files only or select the minimum file size for encryption. In the new Hive variant, we found the following parameters across different samples:

Overall, it appears different versions have different parameters that are constantly updated. Unlike in previous variants where there was a ‘help’ menu, in the new variant, the attacker must know the parameters beforehand. Since all strings are encrypted, it makes finding the parameters challenging for security researchers.

Stopped services and processes

Like most sophisticated malware, Hive stops services and processes associated with security solutions and other tools that might get in the way of its attack chain. Hive tries to impersonate the process tokens of trustedinstaller.exe and winlogon.exe so it can stop Microsoft Defender Antivirus, among other services.

Hive stops the following services:

windefend, msmpsvc, kavsvc, antivirservice, zhudongfungyu, vmm, vmwp, sql, sap, oracle, mepocs, veeam, backup, vss, msexchange, mysql, sophos, pdfservice, backupexec, gxblr, gxvss, gxclmgrs, gxvcd, gxcimgr, gxmmm, gxvsshwprov, gxfwd, sap, qbcfmonitorservice, qbidpservice, acronisagent, veeam, mvarmor, acrsch2svc

It also stops the following processes:

dbsnmp, dbeng50, bedbh, excel, encsvc, visios, firefox, isqlplussvc, mspub, mydesktopqos, notepad, ocautoupds, ocomm, ocssd, onenote, outlook, sqbcoreservice, sql, steam, tbirdconfig, thunderbird, winword, wordpad, xfssvccon, vxmon, benetns, bengien, pvlsvr, raw_agent_svc, cagservice, sap, qbidpservice, qbcfmonitorservice, teamviewer_service, teamviewer, tv_w32, tv_x64, cvd, saphostexec, sapstartsrv, avscc, dellsystemdetect, enterpriseclient, veeam, thebat, cvfwd, cvods, vsnapvss, msaccess, vaultsvc, beserver, appinfo, qbdmgrn, avagent, spooler, powerpnt, cvmountd, synctime, oracle, wscsvc, winmgmt, *sql*

Launched processes

As part of its ransomware activity, Hive typically runs processes that delete backups and prevent recovery. There are differences between versions, and some samples may not execute all these processes, but one sample that starts the most processes is SHA-256: 481dc99903aa270d286f559b17194b1a25deca8a64a5ec4f13a066637900221e:

• “vssadmin.exe delete shadows /all /quiet”
• “wmic.exe shadowcopy delete”
• “wbadmin.exe delete systemstatebackup”
• “wbadmin.exe delete catalog -quiet”
• “bcdedit.exe /set {default} recoveryenabled No”
• “bcdedit.exe /set {default} bootstatuspolicy ignoreallfailures”
• “wbadmin.exe delete systemstatebackup -keepVersions:3”

Ransom note

Hive’s ransom note has also changed, with the new version referencing the .key files with their new file name convention and adding a sentence about virtual machines (VMs).

The older variants had an embedded username and password (marked as hidden). In the new variant, the username and password are taken from the command line parameter -u and are labeled test_hive_username and test_hive_password.

Old ransom note text:

 Your network has been breached and all data were encrypted.
Personal data, financial reports and important documents are ready to disclose.
 
To decrypt all the data and to prevent exfiltrated files to be disclosed at 
http://hive[REDACTED].onion/
you will need to purchase our decryption software.
 
Please contact our sales department at:
 
   http://hive[REDACTED].onion/
  
      Login:    [REDACTED]
      Password: [REDACTED]
 
To get an access to .onion websites download and install Tor Browser at:
   https://www.torproject.org/ (Tor Browser is not related to us)
 
 
Follow the guidelines below to avoid losing your data:
 
- Do not modify, rename or delete *.key.abc12 files. Your data will be 
   undecryptable.
- Do not modify or rename encrypted files. You will lose them.
- Do not report to the Police, FBI, etc. They don't care about your business.
   They simply won't allow you to pay. As a result you will lose everything.
- Do not hire a recovery company. They can't decrypt without the key. 
   They also don't care about your business. They believe that they are 
   good negotiators, but it is not. They usually fail. So speak for yourself.
- Do not reject to purchase. Exfiltrated files will be publicly disclosed.

New ransom note text:

Your network has been breached and all data were encrypted.
Personal data, financial reports and important documents are ready to disclose.
 
To decrypt all the data and to prevent exfiltrated files to be disclosed at 
http://hive[REDACTED].onion/
you will need to purchase our decryption software.
 
Please contact our sales department at:
 
   http://hive[REDACTED].onion/
 
      Login:    test_hive_username
      Password: test_hive_password
 
To get an access to .onion websites download and install Tor Browser at:
   https://www.torproject.org/ (Tor Browser is not related to us)
 
 
Follow the guidelines below to avoid losing your data:
 
- Do not delete or reinstall VMs. There will be nothing to decrypt.
- Do not modify, rename or delete *.key files. Your data will be 
   undecryptable.
- Do not modify or rename encrypted files. You will lose them.
- Do not report to the Police, FBI, etc. They don't care about your business.
   They simply won't allow you to pay. As a result you will lose everything.
- Do not hire a recovery company. They can't decrypt without the key. 
   They also don't care about your business. They believe that they are 
   good negotiators, but it is not. They usually fail. So speak for yourself.
- Do not reject to purchase. Exfiltrated files will be publicly disclosed.

Encryption

The most interesting change in the Hive variant is its cryptography mechanism. The new variant was first uploaded to VirusTotal on February 21, 2022, just a few days after a group of researchers from Kookmin University in South Korea published the paper “A Method for Decrypting Data Infected with Hive Ransomware” on February 17, 2022. After a certain period of development, the new variant first appeared in Microsoft threat data on February 22.

The new variant uses a different set of algorithms: Elliptic Curve Diffie-Hellmann (ECDH) with Curve25519 and XChaCha20-Poly1305 (authenticated encryption with ChaCha20 symmetric cipher).

A unique encryption approach

The new Hive variant uses a unique approach to file encryption. Instead of embedding an encrypted key in each file that it encrypts, it generates two sets of keys in memory, uses them to encrypt files, and then encrypts and writes the sets to the root of the drive it encrypts, both with .key extension.

To indicate which keys set was used to encrypt a file, the name of the .key file containing the corresponding encryption keys is added to the name of the encrypted file on disk, followed by an underscore and then a Base64 string (also adding underscore and hyphen to the character set). Once it’s Base64-decoded, the string contains two offsets, with each offset pointing to a different location in the corresponding .key file. This way, the attacker can decrypt the file using these offsets.

For example, after running Hive, we got the following files dropped to the C:\ drive:

• C:\3bcVwj6j.key
• C:\l0Zn68cb.key

In this example, a file named myphoto.jpg would be renamed to C:\myphoto.jpg.l0Zn68cb _ -B82BhIaGhI8. As we discuss in the following sections, the new variant’s keys set generation is entirely different from old variants. However, its actual file encryption is very similar.

Keys set generation

A buffer of size 0xCFFF00 bytes is allocated. Using two custom functions to generate random bytes (labeled “random_num_gen” and “random_num_gen_2” for demonstration purposes) the buffer is filled. The first 0xA00000 bytes of this buffer are filled with random bytes and the remaining 0x2FFF00 bytes are simply copied from the first 0x2FFF00 random bytes that were copied earlier to the buffer.

The content of each buffer is a keys set (a collection of symmetric keys). Since two buffers are allocated, there are two keys sets. In the encryption process, the malware randomly selects different keys (byte sequences) for each file from one of the keys set and uses them to encrypt the file by XORing the byte sequence of the keys with the file’s content.

A custom 64-byte hash is prepared for each keys set. This hash will be used later.

After the hash is computed and several other strings are decrypted, the encryption process takes the following steps:

1. Generate victim_private_key using the same functions introduced above.

2. Generate victim_public_key using ECDH with Curve25519. The input is victim_private_key and the basepoint is 9 followed by 31 zeros (embedded in the sample).

3. Generate a 24-byte nonce for the XChaCha algorithm, later in Poly1305-XChaCha20.

4. Generate shared_secret using ECDH with Curve25519. The input is victim_private_key and hive_public_key. Then, the  shared_secret (as a key) with hive_public_key (as a nonce) is used to derive the derived_key using ChaCha20.

5. Encrypt the keys set using Poly1305-XChaCha20. The values used for the encryption are the keys set, derived_key, nonce, and the embedded associated data (AD). This function encrypts the keys set and adds a 16-byte authentication tag at the end of the buffer of the encrypted keys. It’s unclear if the authentication tag is ever checked.

Now that the keys set is finally encrypted, the nonce, victim_public_key, the now-encrypted keys set, and the authentication tag are copied to a new buffer, one after another. This buffer (which we label encrypted_structure_1) is treated as a new keys set, which is again encrypted using the same method described above but with a second hive_public_key. This time, the function outputs new nonce, victim_private_key, and others. Only the associated data is the same.

Finally, the new buffer, which contains the second_nonce, second_victim_public_key, and the encryptedencrypted_structure_1, is written to the root of the drive it’s encrypting (for example, C:\). The create_extension function generates a Base64 string based on the first six bytes of the custom hash that was created earlier. This Base64 string serves as the file name, and the extension of the file is simply “.key”.

The diagram below illustrates the encryption scheme described above:

As seen in the diagram above, “Keys sets encryption flow” is executed twice. In the first round it is executed with the original keys set as an input. In the second round it is executed with the “encrypted structure 1” as an input. In its second execution, all other input values are different except the AD (associated data) and the Basepoint 9.

Hence, the following values are new in the second execution: victim_private_key, victim_public_key, hive_public_key, nonce, shared_secret and derived_key.

File encryption

After both keys files are written to the disk, the multi-threaded file encryption starts. Before encrypting each file, the malware checks its name and extension against a list of strings. If there is a match, then the file will not be encrypted. For example, a file with .exe extension will not be encrypted if .exe is in the list of strings. It should be noted that this list is encrypted and decrypted during runtime.

The same file encryption method seen in old variants is used in the new one: two random numbers are generated and used as offsets to the keys set. Each offset is four bytes:

For the encryption, the file’s content is XORed with bytes from the keys set, according to the offsets. The file bytes are XORed twice—once according to the first offset and a second time according to the second offset. Files are encrypted in blocks of 0x100000 bytes, with the maximum number of blocks at 100. There is an interval between the encrypted blocks as defined by block_space. After the encryption is finished in memory, the encrypted data is written to the disk, overwriting the original file.

Looking at when create_extension is called once file encryption has started, we recognized a similar structure in the previous variant:

Let us look at the value (72 D7 A7 A3 F5 5B FF EF 21 6B 11 7C 2A 18 CD 00) in the address of r9 register just before create_extension is called on a file called EDBtmp.log

Recall that in the older variants, 0xFF was used as a delimiter to separate the key file name from the offset values. We can also see it here. Converting the first six bytes (72 D7 A7 A3 F5 5B) to Base64 yields the following:

cteno/Vb

And if we step over create_extension, the result is similar—we get cteno_Vb as the .key file name (note: Since Hive uses a different Base64 character set, “/” was replaced with “_”):

Microsoft will continue to monitor the Hive operators’ activity and implement protections for our customers. The current detections, advanced detections, and indicators of compromise (IOCs) in place across our security products are detailed below.

Recommended customer actions

The techniques used by the new Hive variant can be mitigated by adopting the security considerations provided below:

• Use the included IOCs to investigate whether they exist in your environment and assess for potential intrusion.

Our recent blog on the ransomware as a service economy has an exhaustive guide on how to protect yourself from ransomware threats that dive deep into each of the following areas. We encourage readers to refer to that blog for a comprehensive guide on:

• Building credential hygiene
• Auditing credential exposure
• Prioritizing deployment of Active Directory updates
• Cloud hardening
  • Implement the Azure Security Benchmark and general best practices for securing identity infrastructure.
  • Ensure cloud admins/tenant admins are treated with the same level of security and credential hygiene as Domain Admins.
  • Address gaps in authentication coverage.
• Enforce MFA on all accounts, remove users excluded from MFA, and strictly require MFA from all devices, in all locations, at all times.
• Enable passwordless authentication methods (for example, Windows Hello, FIDO keys, or Microsoft Authenticator) for accounts that support passwordless. For accounts that still require passwords, use authenticator apps like Microsoft Authenticator for MFA.
• Disable legacy authentication.

For Microsoft 365 Defender customers, the following checklist eliminates security blind spots:

• Turn on cloud-delivered protection in Microsoft Defender Antivirus to cover rapidly evolving attacker tools and techniques, block new and unknown malware variants, and enhance attack surface reduction rules and tamper protection.
• Turn on tamper protection features to prevent attackers from stopping security services.
• Run EDR in block mode so that Microsoft Defender for Endpoint can block malicious artifacts, even when a non-Microsoft antivirus doesn’t detect the threat or when Microsoft Defender Antivirus is running in passive mode. EDR in block mode also blocks indicators identified proactively by Microsoft Threat Intelligence teams.
• Enable network protection to prevent applications or users from accessing malicious domains and other malicious content on the internet.
• Enable investigation and remediation in full automated mode to allow Microsoft Defender for Endpoint to take immediate action on alerts to resolve breaches.
• Use device discovery to increase visibility into the network by finding unmanaged devices and onboarding them to Microsoft Defender for Endpoint.
• Protect user identities and credentials using Microsoft Defender for Identity, a cloud-based security solution that leverages on-premises Active Directory signals to monitor and analyze user behavior to identify suspicious user activities, configuration issues, and active attacks.

Indicators of compromise (IOCs)

The below list provides a partial list of the IOCs observed during our investigation and included in this blog. We encourage our customers to investigate these indicators in their environments and implement detections and protections to identify past related activity and prevent future attacks against their systems.

NOTE: These indicators shouldn’t be considered exhaustive for this observed activity.

Detections

Microsoft 365 Defender

Microsoft Defender Antivirus

Microsoft Defender Antivirus provides detection for this threat under the following family names with build version 1.367.405.0 or later.

• Ransom:Win64/Hive
• Ransom:Win32/Hive

Microsoft Defender for Endpoint detection

Microsoft Defender for Endpoint customers may see any or a combination of the following alerts as an indication of possible attack. These alerts are not necessarily an indication of a Hive compromise, but should be investigated:

• Ransomware behavior detected in the file system
• File backups were deleted
• Possible ransomware infection modifying multiple files
• Possible ransomware activity
• Ransomware-linked emerging threat activity group detected

Advanced hunting queries

Microsoft Sentinel

To locate possible Hive ransomware activity mentioned in this blog post, Microsoft Sentinel customers can use the queries detailed below:

Identify Hive ransomware IOCs

This query identifies a match across various data feeds for IOCs related to Hive ransomware.

https://github.com/Azure/Azure-Sentinel/blob/master/Detections/MultipleDataSources/HiveRansomwareJuly2022.yaml

Identify backup deletion

This hunting query helps detect a ransomware’s attempt to delete backup files.

https://github.com/Azure/Azure-Sentinel/blob/master/Hunting%20Queries/MultipleDataSources/BackupDeletion.yaml

Identify Microsoft Defender Antivirus detection of Hive ransomware

This query looks for Microsoft Defender Antivirus detections related to the Hive ransomware and joins the alert with other data sources to surface additional information such as device, IP, signed-in users, etc.

https://github.com/Azure/Azure-Sentinel/blob/master/Detections/SecurityAlert/HiveRansomwareAVHits.yaml

The post Hive ransomware gets upgrades in Rust appeared first on Microsoft Security Blog.

To learn about how the new taxonomy represents the origin, unique traits, and impact of threat actors, and to get a complete mapping of threat actor names, read this blog: Microsoft shifts to a new threat actor naming taxonomy.

The BlackCat ransomware, also known as ALPHV, is a prevalent threat and a prime example of the growing ransomware as a service (RaaS) gig economy. It’s noteworthy due to its unconventional programming language (Rust), multiple target devices and possible entry points, and affiliation with prolific threat activity groups. While BlackCat’s arrival and execution vary based on the actors deploying it, the outcome is the same—target data is encrypted, exfiltrated, and used for “double extortion,” where attackers threaten to release the stolen data to the public if the ransom isn’t paid.

First observed in November 2021, BlackCat initially made headlines because it was one of the first ransomware families written in the Rust programming language. By using a modern language for its payload, this ransomware attempts to evade detection, especially by conventional security solutions that might still be catching up in their ability to analyze and parse binaries written in such language. BlackCat can also target multiple devices and operating systems. Microsoft has observed successful attacks against Windows and Linux devices and VMWare instances.

As we previously explained, the RaaS affiliate model consists of multiple players: access brokers, who compromise networks and maintain persistence; RaaS operators, who develop tools; and RaaS affiliates, who perform other activities like moving laterally across the network and exfiltrating data before ultimately launching the ransomware payload. Thus, as a RaaS payload, how BlackCat enters a target organization’s network varies, depending on the RaaS affiliate that deploys it. For example, while the common entry vectors for these threat actors include remote desktop applications and compromised credentials, we also saw a threat actor leverage Exchange server vulnerabilities to gain target network access. In addition, at least two known affiliates are now adopting BlackCat: DEV-0237 (known for previously deploying Ryuk, Conti, and Hive) and DEV-0504 (previously deployed Ryuk, REvil, BlackMatter, and Conti).

Such variations and adoptions markedly increase an organization’s risk of encountering BlackCat and pose challenges in detecting and defending against it because these actors and groups have different tactics, techniques, and procedures (TTPs). Thus, no two BlackCat “lives” or deployments might look the same. Indeed, based on Microsoft threat data, the impact of this ransomware has been noted in various countries and regions in Africa, the Americas, Asia, and Europe.

Human-operated ransomware attacks like those that deploy BlackCat continue to evolve and remain one of the attackers’ preferred methods to monetize their attacks. Organizations should consider complementing their security best practices and policies with a comprehensive solution like Microsoft 365 Defender, which offers protection capabilities that correlate various threat signals to detect and block such attacks and their follow-on activities.

In this blog, we provide details about the ransomware’s techniques and capabilities. We also take a deep dive into two incidents we’ve observed where BlackCat was deployed, as well as additional information about the threat activity groups that now deliver it. Finally, we offer best practices and recommendations to help defenders protect their organizations against this threat, including hunting queries and product-specific mitigations.

BlackCat’s anatomy: Payload capabilities

As mentioned earlier, BlackCat is one of the first ransomware written in the Rust programming language. Its use of a modern language exemplifies a recent trend where threat actors switch to languages like Rust or Go for their payloads in their attempt to not only avoid detection by conventional security solutions but also to challenge defenders who may be trying to reverse engineer the said payloads or compare them to similar threats.

BlackCat can target and encrypt Windows and Linux devices and VMWare instances. It has extensive capabilities, including self-propagation configurable by an affiliate for their usage and to environment encountered.

In the instances we’ve observed where the BlackCat payload did not have administrator privileges, the payload was launched via dllhost.exe, which then launched the following commands below (Table 1) via cmd.exe. These commands could vary, as the BlackCat payload allows affiliates to customize execution to the environment.

The flags used by the attackers and the options available were the following: -s -d -f -c; –access-token; –propagated; -no-prop-servers

User account control (UAC) bypass

BlackCat can bypass UAC, which means the payload will successfully run even if it runs from a non-administrator context. If the ransomware isn’t run with administrative privileges, it runs a secondary process under dllhost.exe with sufficient permissions needed to encrypt the maximum number of files on the system.

Domain and device enumeration

The ransomware can determine the computer name of the given system, local drives on a device, and the AD domain name and username on a device. The malware can also identify whether a user has domain admin privileges, thus increasing its capability of ransoming more devices.

Self-propagation

BlackCat discovers all servers that are connected to a network. The process first broadcasts NetBIOS Name Service (NBNC) messages to check for these additional devices. The ransomware then attempts to replicate itself on the answering servers using the credentials specified within the config via PsExec.

Hampering recovery efforts

BlackCat has numerous methods to make recovery efforts more difficult. The following are commands that might be launched by the payload, as well as their purposes:

• Modify boot loader
  • “C:\Windows\system32\cmd.exe” /c “bcdedit /set {default}”
  • “C:\Windows\system32\cmd.exe” /c “bcdedit /set {default} recoveryenabled No”
• Delete volume shadow copies
  • “C:\Windows\system32\cmd.exe” /c “vssadmin.exe Delete Shadows /all /quiet”
  • “C:\Windows\system32\cmd.exe” /c “wmic.exe Shadowcopy Delete”
• Clear Windows event logs
  • “C:\Windows\system32\cmd.exe” /c “cmd.exe /c  for /F \”tokens=*\” Incorrect function. in (‘ wevtutil.exe el ‘) DO wevtutil.exe cl \”Incorrect function. \””

Slinking its way in: Identifying attacks that can lead to BlackCat ransomware

Consistent with the RaaS model, threat actors utilize BlackCat as an additional payload to their ongoing campaigns. While their TTPs remain largely the same (for example, using tools like Mimikatz and PsExec to deploy the ransomware payload), BlackCat-related compromises have varying entry vectors, depending on the ransomware affiliate conducting the attack. Therefore, the pre-ransom steps of these attacks can also be markedly different.

For example, our research noted that one affiliate that deployed BlackCat leveraged unpatched Exchange servers or used stolen credentials to access target networks. The following sections detail the end-to-end attack chains of these two incidents we’ve observed.

Case study 1: Entry via unpatched Exchange

In one incident we’ve observed, attackers took advantage of an unpatched Exchange server to enter the target organization.

Discovery

Upon exploiting the Exchange vulnerability, the attackers launched the following discovery commands to gather information about the device they had compromised:

• cmd.exe and the commands ver and systeminfo – to collect operating system information
• net.exe – to determine domain computers, domain controllers, and domain admins in the environment

After executing these commands, the attackers navigated through directories and discovered a passwords folder that granted them access to account credentials they could use in the subsequent stages of the attack. They also used the del command to delete files related to their initial compromise activity.

The attackers then mounted a network share using net use and the stolen credentials and began looking for potential lateral movement targets using a combination of methods. First, they used WMIC.exe using the previously gathered device name as the node, launched the command whoami /all, and pinged google.com to check network connectivity. The output of the results were then written to a .log file on the mounted share. Second, the attackers used PowerShell.exe with the cmdlet Get-ADComputer and a filter to gather the last sign-in event.

Lateral movement

Two and a half days later, the attackers signed into one of the target devices they found during their initial discovery efforts using compromised credentials via interactive sign-in. They opted for a credential theft technique that didn’t require dropping a file like Mimikatz that antivirus products might detect. Instead, they opened Taskmgr.exe, created a dump file of the LSASS.exe process, and saved the file to a ZIP archive.

The attackers continued their previous discovery efforts using a PowerShell script version of ADRecon (ADRecon.ps1), which is a tool designed to gather extensive information about an Active Directory (AD) environment. The attacker followed up this action with a net scanning tool that opened connections to devices in the organization on server message block (SMB) and remote desktop protocol (RDP). For discovered devices, the attackers attempted to navigate to various network shares and used the Remote Desktop client (mstsc.exe) to sign into these devices, once again using the compromised account credentials.

These behaviors continued for days, with the attackers signing into numerous devices throughout the organization, dumping credentials, and determining what devices they could access.

Collection and exfiltration

On many of the devices the attackers signed into, efforts were made to collect and exfiltrate extensive amounts of data from the organization, including domain settings and information and intellectual property. To do this, the attackers used both MEGAsync and Rclone, which were renamed as legitimate Windows process names (for example, winlogon.exe, mstsc.exe).

Exfiltration of domain information to identify targets for lateral movement

Collecting domain information allowed the attackers to progress further in their attack because the said information could identify potential targets for lateral movement or those that would help the attackers distribute their ransomware payload. To do this, the attackers once again used ADRecon.ps1with numerous PowerShell cmdlets such as the following:

• Get-ADRGPO – gets group policy objects (GPO) in a domain
• Get-ADRDNSZone – gets all DNS zones and records in a domain
• Get-ADRGPLink – gets all group policy links applied to a scope of management in a domain

Additionally, the attackers dropped and used ADFind.exe commands to gather information on persons, computers, organizational units, and trust information, as well as pinged dozens of devices to check connectivity.

Exfiltration for double extortion

Intellectual property theft likely allowed the attackers to threaten the release of information if the subsequent ransom wasn’t paid—a practice known as “double extortion.” To steal intellectual property, the attackers targeted and collected data from SQL databases. They also navigated through directories and project folders, among others, of each device they could access, then exfiltrated the data they found in those. 

The exfiltration occurred for multiple days on multiple devices, which allowed the attackers to gather large volumes of information that they could then use for double extortion.

Encryption and ransom

It was a full two weeks from the initial compromise before the attackers progressed to ransomware deployment, thus highlighting the need for triaging and scoping out alert activity to understand accounts and the scope of access an attacker gained from their activity. Distribution of the ransomware payload using PsExec.exe proved to be the most common attack method.

Case study 2: Entry via compromised credentials

In another incident we observed, we found that a ransomware affiliate gained initial access to the environment via an internet-facing Remote Desktop server using compromised credentials to sign in.

Lateral movement

Once the attackers gained access to the target environment, they then used SMB to copy over and launch the Total Deployment Software administrative tool, allowing remote automated software deployment. Once this tool was installed, the attackers used it to install ScreenConnect (now known as ConnectWise), a remote desktop software application.

Credential theft

ScreenConnect was used to establish a remote session on the device, allowing attackers interactive control. With the device in their control, the attackers used cmd.exe to update the Registry to allow cleartext authentication via WDigest, and thus saved the attackers time by not having to crack password hashes. Shortly later, they used the Task Manager to dump the LSASS.exe process to steal the password, now in cleartext.

Eight hours later, the attackers reconnected to the device and stole credentials again. This time, however, they dropped and launched Mimikatz for the credential theft routine, likely because it can grab credentials beyond those stored in LSASS.exe. The attackers then signed out.

Persistence and encryption

A day later, the attackers returned to the environment using ScreenConnect. They used PowerShell to launch a command prompt process and then added a user account to the device using net.exe. The new user was then added to the local administrator group via net.exe.

Afterward, the attackers signed in using their newly created user account and began dropping and launching the ransomware payload. This account would also serve as a means of additional persistence beyond ScreenConnect and their other footholds in the environment to allow them to re-establish their presence, if needed. Ransomware adversaries are not above ransoming the same organization twice if access is not fully remediated.

Chrome.exe was used to navigate to a domain hosting the BlackCat payload. Notably, the folder structure included the organization name, indicating that this was a pre-staged payload specifically for the organization. Finally, the attackers launched the BlackCat payload on the device to encrypt its data.

Ransomware affiliates deploying BlackCat

Apart from the incidents discussed earlier, we’ve also observed two of the most prolific affiliate groups associated with ransomware deployments have switched to deploying BlackCat. Payload switching is typical for some RaaS affiliates to ensure business continuity or if there’s a possibility of better profit. Unfortunately for organizations, such adoption further adds to the challenge of detecting related threats.

Microsoft tracks one of these affiliate groups as DEV-0237. Also known as FIN12, DEV-0237 is notable for its distribution of Hive, Conti, and Ryuk ransomware. We’ve observed that this group added BlackCat to their list of distributed payloads beginning March 2022. Their switch to BlackCat from their last used payload (Hive) is suspected to be due to the public discourse around the latter’s decryption methodologies.

DEV-0504 is another active affiliate group that we’ve seen switching to BlackCat for their ransomware attacks. Like many RaaS affiliate groups, the following TTPs might be observed in a DEV-0504 attack:

• Entry vector that can involve the affiliate remotely signing into devices with compromised credentials, such as into devices running software solutions that allow for remote work
• The attackers’ use of their access to conduct discovery on the domain
• Lateral movement that potentially uses the initial compromised account
• Credential theft with tools like Mimikatz and Rubeus

DEV-0504 typically exfiltrates data on devices they compromise from the organization using a malicious tool such as StealBit—often named “send.exe” or “sender.exe”. PsExec is then used to distribute the ransomware payload. The group has been observed delivering the following ransom families before their adoption of BlackCat beginning December 2021:

• BlackMatter
• Conti
• LockBit 2.0
• Revil
• Ryuk

Defending against BlackCat ransomware

Today’s ransomware attacks have become more impactful because of their growing industrialization through the RaaS affiliate model and the increasing trend of double extortion. The incidents we’ve observed related to the BlackCat ransomware leverage these two factors, making this threat durable against conventional security and defense approaches that only focus on detecting the ransomware payloads. Detecting threats like BlackCat, while good, is no longer enough as human-operated ransomware continues to grow, evolve, and adapt to the networks they’re deployed or the attackers they work for.

Instead, organizations must shift their defensive strategies to prevent the end-to-end attack chain. As noted above, while attackers’ entry points may vary, their TTPs remain largely the same. In addition, these types of attacks continue to take advantage of an organization’s poor credential hygiene and legacy configurations or misconfigurations to succeed. Therefore, defenders should address these common paths and weaknesses by hardening their networks through various best practices such as access monitoring and proper patch management. We provide detailed steps on building these defensive strategies against ransomware in this blog.

In the BlackCat-related incidents we’ve observed, the common entry points for ransomware affiliates were via compromised credentials to access internet-facing remote access software and unpatched Exchange servers. Therefore, defenders should review their organization’s identity posture, carefully monitor external access, and locate vulnerable Exchange servers in their environment to update as soon as possible. The financial impact, reputation damage, and other repercussions that stem from attacks involving ransomware like BlackCat are not worth forgoing downtime, service interruption, and other pain points related to applying security updates and implementing best practices.

Leveraging Microsoft 365 Defender’s comprehensive threat defense capabilities

Microsoft 365 Defender helps protect organizations from attacks that deliver the BlackCat ransomware and other similar threats by providing cross-domain visibility and coordinated threat defense. It uses multiple layers of dynamic protection technologies and correlates threat data from email, endpoints, identities, and cloud apps. Microsoft Defender for Endpoint detects tools like Mimikatz, the actual BlackCat payload, and subsequent attacker behavior. Threat and vulnerability management capabilities also help discover vulnerable or misconfigured devices across different platforms; such capabilities could help detect and block possible exploitation attempts on vulnerable devices, such as those running Exchange. Finally, advanced hunting lets defenders create custom detections to proactively surface this ransomware and other related threats.

Additional mitigations and recommendations

Defenders can also follow the following steps to reduce the impact of this ransomware:

• Turn on Microsoft Defender Antivirus. Turn on cloud-delivered protection in Microsoft Defender Antivirus or the equivalent for your antivirus product to cover rapidly evolving attacker tools and techniques. Cloud-based machine learning protections block a large amount of new and unknown variants.
• Enforce strong, randomized local administrator passwords. Use tools like Local Administrator Password Solution (LAPS).
• Require multifactor authentication (MFA) for local device access, RDP access, and remote connections through virtual private networks (VPNs) and Outlook Web Access. Solutions like Windows Hello or Fast ID Online (FIDO) v2.0 security keys let users sign in using biometrics and/or a physical key or device.
• Turn on Microsoft Defender Firewall.
• Implement controlled folder access to help prevent files from being altered or encrypted by ransomware. Set controlled folder access to Enabled or Audit mode.
• Investigate and remediate vulnerabilities in Exchange servers. Also, determine if implementing the Exchange Emergency Mitigation service is feasible for your environment. This service helps keep your Exchange servers secure by applying mitigations to address potential threats against your servers.

Microsoft 365 Defender customers can also apply the additional mitigations below:

• Use advanced protection against ransomware.
• Turn on tamper protection in Microsoft Defender for Endpoint to prevent malicious changes to security settings. Enable network protection in Microsoft Defender for Endpoint and Microsoft 365 Defender to prevent applications or users from accessing malicious domains and other malicious content on the internet.
• Ensure Exchange servers have applied the mitigations referenced in the related Threat Analytics report.
• Turn on the following attack surface reduction rules to block or audit activity associated with this threat:
  • Block credential stealing from the Windows local security authority subsystem (lsass.exe)
  • Block process creations originating from PSExec and WMI commands
  • Block executable files from running unless they meet a prevalence, age, or trusted list criterion

For a full list of ransomware mitigations regardless of threat, refer to this article: Rapidly protect against ransomware and extortion.

Learn how you can stop attacks through automated, cross-domain security and built-in AI with Microsoft Defender 365.

Microsoft 365 Defender Threat Intelligence Team

Appendix

Microsoft 365 Defender detections

Microsoft Defender Antivirus

• Ransom:Win32/BlackCat!MSR
• Ransom:Win32/BlackCat.MK!MTB
• Ransom:Linux/BlackCat.A!MTB

Microsoft Defender for Endpoint EDR

Alerts with the following titles in the security center can indicate threat activity on your network:

• An active ‘BlackCat’ ransomware was detected
• ‘BlackCat’ ransomware was detected
• BlackCat ransomware

Hunting queries

Microsoft 365 Defender

To locate possible ransomware activity, run the following queries.

Suspicious process execution in PerfLogs path

Use this query to look for processes executing in PerfLogs—a common path used to place the ransomware payloads.

DeviceProcessEvents
| where InitiatingProcessFolderPath has "PerfLogs"
| where InitiatingProcessFileName matches regex "[a-z]{3}.exe"
| extend Length = strlen(InitiatingProcessFileName)
| where Length == 7

Suspicious registry modification of MaxMpxCt parameters

Use this query to look for suspicious running processes that modify registry settings to increase the number of outstanding requests allowed (for example, SMB requests when distributing ransomware via its PsExec methodology).

DeviceProcessEvents
| where ProcessCommandLine has_all("LanmanServer", "parameters", "MaxMpxCt", "65535")

Suspicious command line indicative of BlackCat ransom payload execution

Use these queries to look for instances of the BlackCat payload executing based on a required command argument for it to successfully encrypt ‘–access-token’.

DeviceProcessEvents
| where ProcessCommandLine has_all("--access-token", "-v") 
| extend CommandArguments = split(ProcessCommandLine, " ")
| mv-expand CommandArguments
| where CommandArguments matches regex "^[A-Fa-f0-9]{64}$"

DeviceProcessEvents
| where InitiatingProcessCommandLine has "--access-token"
| where ProcessCommandLine has "get uuid"

Suspected data exfiltration

Use this query to look for command lines that indicate data exfiltration and the indication that an attacker may attempt double extortion.

DeviceNetworkEvents
| where InitiatingProcessCommandLine has_all("copy", "--max-age", "--ignore-existing", "--multi-thread-streams", "--transfers") and InitiatingProcessCommandLine has_any("ftp", "ssh", "-q")

The post The many lives of BlackCat ransomware appeared first on Microsoft Security Blog.

Derived from the Zeus banking trojan first discovered in 2007, ZLoader is a malware family notable for its ability to evolve and change from campaign to campaign, having undergone much development since its inception. ZLoader has remained relevant as attackers’ tool of choice by including defense evasion capabilities, like disabling security and antivirus tools, and selling access-as-a-service to other affiliate groups, such as ransomware operators. Its capabilities include capturing screenshots, collecting cookies, stealing credentials and banking data, performing reconnaissance, launching persistence mechanisms, misusing legitimate security tools, and providing remote access to attackers.

ZLoader campaign operators evolved the malware from a basic banking trojan to a more sophisticated piece of malware capable of monetizing compromised devices by selling access to other affiliate groups. By leveraging and misusing legitimate tools like Cobalt Strike and Splashtop, affiliates gain hands-on-keyboard access to affected devices, which can be further misused for other malicious activities like credential theft or downloading additional payloads, including ransomware. ZLoader has previously been linked to ransomware infections such as Ryuk, DarkSide, and BlackMatter.

ZLoader attacks have affected nations around the world, with the majority targeting the US, China, western Europe, and Japan. Due to the modular nature of some of ZLoader’s capabilities and its constant shifts in techniques, different ZLoader campaigns may look nothing alike. Previous campaigns have been fairly simple, with the malware delivered via malicious Office macros attached to emails and then used to deploy modules for capabilities. Other, more recent campaigns are notably complex–injecting malicious code into legitimate processes, disabling antivirus solutions, and ultimately culminating in ransomware.

ZLoader operators have also updated their methodology to frequently deliver the malware through targeted malicious Google Ads. The use of ad fraud is a stealthy way to target end users as it bypasses typical security solutions that can be found in email and surfaces itself in normal browser activities instead.

Microsoft Defender for Endpoint detects malicious behaviors related to this campaign. Enabling cloud protection and automatic sample submission for Microsoft Defender Antivirus aids users and organizations in remaining protected on new and emerging threats. Moreover, standardizing the use of the Microsoft Edge browser across all corporate devices and enabling Microsoft Defender SmartScreen protection blocks malicious sites, such as those connected to ZLoader campaigns. 

In this blog post, we characterize the various methods by which a ZLoader campaign might be identified, along with detailing detection and mitigation information that can help users reduce the impact of this threat.

ZLoader attack chains

ZLoader is a malware variant that has evolved over the years and is used for multiple objectives, meaning that two campaigns which both use ZLoader may appear completely different. For example, an individual who has experience responding to a ZLoader campaign that originated from email and dropped the payload via a malicious Office macro, may be shocked at the complexity of a second ZLoader campaign that uses numerous malicious files for reconnaissance and antivirus tampering, before finally dropping the actual malware payload.

The following diagram identifies the most common ways the ZLoader trojan has been observed moving through the delivery, installation, payload, malware activity, and follow-on activity phases of an attack. This diagram is high-level and may not depict every step or file dropped in some of ZLoader’s more complex campaigns.

Delivery

ZLoader malware has been observed being delivered in multiple ways. Two of the most prominent methods include malicious search engine ads and malicious emails.

Malicious advertisement delivery

In more recent campaigns, ZLoader has shifted away from using email as a means of delivery and instead used malicious ads on search engines such as Google to trick users into visiting malicious sites.

Each wave of these campaigns impersonated a specific company or product, such as Java, Zoom, TeamViewer, and Discord. For the delivery stage of the attack, the actors would purchase Google Ads for key terms associated with those products, such as “zoom videoconference.” Users who performed Google searches for those terms during a specific time would be presented with an advertisement that led to the form grabbing malicious domains.

In each instance of this campaign, the actors would compromise legitimate domains that appeared to be owned by individuals or small businesses, such as personal blogs. They would then set up subdomains on them that were associated with the product they were impersonating during that time. The product-specific subdomain was the second subdomain on the domain, while the first subdomain was an extremely long set of words. For example:

• zoomdownload[.]linkforbusinessandpersonalusersofourserviceinseptember[.]jumpingonwater[.]com
• zoomonline[.]forusersinourservicewithbusinessandpersonalcustomers[.]fineanddandiwithrandi[.]com
• zoomdownload[.]onlinestartserviceforyourworkstudymeeting[.]indyflat-tax[.]com
• zoomdownloadlink[.]zoomdownload[.]onlinesoftwareforpersonalandbusinessusersinseptember[.]lifeintrainingpodcast[.]com
• teamviewerdownload[.]fastserviceworkonlinelinkjoininaugustseptermber[.]greenlinefood[.]net
• teamviewerdownload[.]directserviceforonlinepersonalandbusinessusersofourservice[.]wahatalrabeeh[.]co
• teamviewerstart[.]linkforpersonalandbusinessusersinourservicestartnow[.]ellisclinic[.]com

In at least one instance of this activity, the compromised webpage was set up to appear as though it was associated with the company Get VoIP, a legitimate service that provides comparisons between various VoIP providers. The attackers did not compromise the GetVoIP website or service, rather, they designed the webpage to impersonate the real GetVoIP site.

From these compromised domains, the users will attempt to download the product being impersonated, which redirects them to an attacker-owned domain. These domains also pretend to be associated with the legitimate product being impersonated, and frequently use the .site TLD.

One example of the chain of redirected domains associated with this activity is:

1. https://adservice.google[.]com, redirects to:
2. zoomdownload.linkforbusinessandpersonalusersofourserviceinseptember.jumpingonwater[.]com, redirects to:
3. zoomvideo[.]site

The ZLoader operators have tended to use REG.RU, LLC as the registrar for these final .site domains. Additionally, many of the domains used within a single campaign have the registrant contact email in common with each other, making it easy to pivot and find other potentially related domains.

The final website in this chain downloads the initial malicious .msi file.

Email delivery

As with many other malware variants, prior ZLoader campaigns have also been known to use malicious emails to deliver Office documents containing malicious macros that download the payload. The ZLoader operators do not have a preferred method of delivering these Office documents and have been observed using both links and attachments in various campaigns. Some observed means by which a ZLoader email was associated with a malicious document include:

• Attached macro-enabled Microsoft Office document 
• Attached Excel 4.0 document that contained Hidden Sheets and Very Hidden Sheets to host macros 
• Attached PDF with link to a macro-enabled Office document 
• Attached ZIP file that contained a macro-enabled Office document or executable
• Link to a Google Docs page with links to a macro-enabled Office document

The emails have used a variety of lures, which typically convey a sense of urgency. Some of the campaigns used lures based on currents events at the time of the campaign, such COVID-19, or generic lures, such as overdue invoice payments and fake resumes or CVs. Additionally, most of these emails have been sent from consumer email services—notably AOL.com. There have also been campaigns that used domains that are associated with the lure theme; for example, some emails were sent from a COVID-themed sender domain.

Regardless of how the operator chooses to deliver the Office document, once the user opens it, they are prompted to enable macros to view the content. In various known cases, the malicious macros either directly started to download subsequent payloads or they dropped a VBS file that in turn performed the download.

In general, a connection was made to a compromised WordPress instance hosting the PHP code used by the ZLoader kit. At this stage, the ZLoader payload was downloaded as a DLL masquerading as an HTML file that is then launched using rundll32.exe.  

Installation

Less complex ZLoader campaigns go straight from the delivery phase to dropping the malicious payload. In more complex ZLoader campaigns, the next phase of the attack shifts to using a legitimate process such as msiexec.exe to download several additional files, including many non-malicious .dll files that are legitimate pieces of whatever software is being impersonated at the time. A malicious .bat file is hidden in those .dll files.

In several instances, these files were added to a folder pretending to be associated with legitimate software, such as Oracle Java or Brave Browser, using the following pattern as an example: C:Program Files (x86)Sun Technology NetworkOracle Java SE[malicious file].

The .bat file launches PowerShell to reach out to a download domain to drop the ZLoader payload. Examples of these domains include:

• quickbooks[.]pw
• sweepcakesoffers[.]com
• Datalystoy[.]com
• Teamworks455[.]com
• Clouds222[.]com

In some campaigns, the attackers used a script to run various discovery commands prior to downloading the ZLoader payload, including:

• ipconfig /all
• net config workstation
• net view /all
• net view /all /domain
• nltest /domain_trusts
• nltest /domain_trusts /all_trusts

Payload

Once the ZLoader payload is on the device, it may drop various modules that provide it with additional functionality, such as: 

• Capturing screenshots 
• Collecting cookies 
• Stealing banking passwords 
• Providing VNC access to attackers 

Operators can choose which of these modules to deliver based on how the malware is configured. In most campaigns, the module files are dropped in subfolders in the AppData folder. Although operators are free to give the subfolders and files arbitrary names, the names Microsoft researchers have actually observed exhibit two patterns:

• Sets of characters that appear random 
• Concatenated dictionary words 

In several campaigns, attackers opted not to use these modules and instead used the payload to download an additional malicious file. This file was launched and then called back out to the same download domain that the ZLoader payload was downloaded from, to download a PowerShell script. The downloaded script checked if the device was workgroup- or domain-connected. The PowerShell script then reached out to the command and control (C2) domain and downloaded two malicious files—typically an .exe and a .dll. The script used regsvr32.exe to launch the DLL and run a command to time out for 200 seconds. After this, cmd.exe was used to launch an additional malicious file, which downloads a VBS file that is loaded by wscript.

These files were used to tamper with security solutions and to grant attackers hands-on-keyboard access.

Browser credential theft

One of the main functionalities of ZLoader malware is to steal online credentials targeting banks and financial institutions, as well as other credentials, via client-side web injection and form grabbing attacks. Web injection allows the attacker to alter content of the websites displayed to the victim, while form grabbing captures credentials from the browser windows. To accomplish those actions, the malware implements an Adversary-in-the-browser (AiTB) attack. 

ZLoader’s main process, msiexec.exe, spawns several threads running at the same time to perform different tasks. Each of these threads communicate with one another using shared data stored in the global memory, system registry, and encrypted files. Threads are spawned that execute functions to install a fake certificate and run a local proxy, while another thread is injected and executed inside the loaded browser process, which is responsible for redirecting traffic via proxy.

A thread runs to traverse the list of running processes and inject codes to target browser processes discovered. ZLoader targets the following browser processes:

• iexplore.exe
• firefox.exe
• chrome.exe
• msedge.exe (Microsoft Edge)

The hook API TranslateMessage is the key malware functionality that performs the form grabbing, keylogging, and screenshotting of users’ desktops. 

For the target browser processes, the following APIs are hooked for tracking, redirecting network activities, and controlling the certificate verification. The ZwDeviceIoControlFile hooks allow HTTP/HTTPs responses containing web pages codes from the target to be redirected to the proxy server to be modified. Moreover, any certificate will be tagged as valid. 

• ntdll.dll – ZwDeviceIoControlFile
• crypt32.dll – CertGetCertificateChain, CertVerifyCertificateChainPolicy

Another thread is responsible for checking instructions and configurations from the C2 servers every 10 minutes. Included in the configuration are the list of target banks, financial institutions, and online companies, and the instruction on how to perform the web injection.

One of ZLoader’s targets is the Microsoft online sign-in page at https://login.microsoftonline[.]com. Several of Microsoft’s main websites, such as office[.]com, redirect users to this Microsoft online page when they try to sign into their Microsoft account. When users load their favorite web browser, such as Microsoft Edge, then visit and try to sign into their Microsoft account, ZLoader will match the URL to the list of targets. In this case it will match to the first one above and perform the web injection by inserting malicious JavaScript codes after the string “</head>” and then rendering to the browser application.

The codes injected will insert fake web controls and/or additional JavaScript codes that are responsible for capturing the credentials such as usernames, passwords, and others. This captured information is encrypted and sent to the main bot and then to the C2 server. With these stolen credentials, the ZLoader operators can potentially gain access to users’ Microsoft online account to perform further illicit activities. As the malicious activities occurred in the background, even “tech savvy” users may not be aware that their browser was tampered with, and credentials were stolen.

Defense evasion

ZLoader has used various methods of defense evasion, focused on attempting to appear more legitimate or by disabling security tools. In multiple campaigns associated with malicious ads, the ZLoader operators would sign malicious files used in their attack chain. Signing these files is intended to make them appear to be legitimate, non-malicious files used by real software, rather than malicious files used by malware.

The first method ZLoader has used to sign files is by creating fictitious companies. In certain campaigns, the .msi files that are installed on the device after the user visits a malicious ad are signed by a fictitious company created by the operator for the purpose of the campaign. The malware operators created multiple fraudulent companies, such as Flyintellect Inc, and Datalyst Oy, in several campaigns. Due to the way .msi files are designed, the registry keys that are added by this activity later in the attack chain are also published by the same company name.

Another method operators have used to evade detection is a set of techniques that utilize validly-signed files to hide malicious scripts through vulnerabilities like CVE-2020-1599, CVE-2013-3900, and CVE-2012-0151.

ZLoader operators have also attempted to perform defense evasion by disabling security tools. In many instances, ZLoader will drop a file, frequently a .bat file, that then uses PowerShell to turn off and alter security settings, such as excluding all .dll and .exe files and regsvr32.exe from being scanned.

Persistence

ZLoader has used various persistence methods across separate campaigns. The first method observed by Microsoft Security Researchers involves the ZLoader DLL using rundll32.exe to register itself. In other documented cases, it also creates the following persistence mechanisms for itself or its modules: 

• Registry entries under HKEY_CURRENT_USERSoftwareMicrosoftWindowsCurrentVersionRun 
• Files in the Startup folder 

In more recent campaigns, the attackers maliciously used Atera, a legitimate remote monitoring software. While Atera was not compromised, attackers leveraged its built-in Splashtop Remote Access capabilities to achieve persistence on the compromised device.

Objectives

April 2023 update – Microsoft Threat Intelligence has shifted to a new threat actor naming taxonomy aligned around the theme of weather. ELBRUS is now tracked as Sangria Tempest.

To learn about how the new taxonomy represents the origin, unique traits, and impact of threat actors, and to get a complete mapping of threat actor names, read this blog: Microsoft shifts to a new threat actor naming taxonomy.

After establishing persistence, the campaign operators behind ZLoader infections monetize their access to domain-joined devices by selling access-as-a-service to other groups, including ransomware affiliates. These groups can then use this access for their own goals, including installations of Cobalt Strike, which enables hands-on keyboard activities by the actors.

In one instance, the VBS downloaded a batch script which connected to a Cobalt Strike C2 via a DLL beacon dropped on the device by PowerShell. It was launched via rundll32.exe, with the known Cobalt Strike flag StartW. Reconnaissance queries were then run on domain-joined devices, performing actions such as searching for all domain trusts on the network.

With the use of Cobalt Strike and Splashtop, attackers have hands-on-keyboard access to affected devices that can be leveraged for subsequent objectives, including credential theft or deployment of additional payloads such as ransomware.

In the past, ZLoader has been tied to ransomware infections such as Ryuk. We’ve also seen ZLoader operators provide access to ELBRUS actors who deployed DarkSide ransomware (earlier in 2021). Those that were more recently observed had been deploying BlackMatter ransomware. Given such history, the Cobalt Strike payloads might indicate pre-ransomware activities that prefigure a real threat of ransomware attacks.

Defending against ZLoader attacks

The take down effort against ZLoader is just one of the ways in which Microsoft provides real-world protection against threats. This action will result in protection for a wide range of organizations around the world from malware, affiliates with hands-on-keyboard access, and additional payloads delivered via ZLoader’s infrastructure.

Like many modern malware variants, getting ZLoader onto a device is oftentimes just the first step in what ends up being a larger attack. The trojan further exemplifies the trend of common malware increasingly harboring more dangerous threats, a pattern also observed in other platforms. ZLoader operators frequently monetize access from infections by selling it to other affiliate groups, who then use the purchased access to carry out their own malicious objectives. Affiliates may further misuse legitimate tools like Cobalt Strike or Splashtop to gain full hands-on-keyboard access to target devices, enabling attackers to perform additional discovery, find high-value targets on the network, move laterally, and drop additional payloads, such as ransomware variants.

The best advice for preventing ZLoader infections is to simply avoid downloading attachments contained in emails from unknown senders as well as clicking on sponsored ads and links in search engine results, instead opting for unsponsored results from verified, trusted sources. Good credential hygiene, network segmentation, and similar best practices increase the “cost” to attackers, helping disrupt their activities before they reach their target.

Defenders can take the following mitigation steps to defend against this threat:

• Encourage users to use Microsoft Edge and other web browsers that support Microsoft Defender SmartScreen, which identifies and blocks malicious websites, including phishing sites, scam sites, and sites that contain exploits and host malware. SmartScreen removes the reputation information for the certificates leveraged during these attacks. Binaries signed with those certificates will trigger a warning about an “unrecognized app.”
• Use Windows Defender Application Control, AppLocker, or other application control technologies to prevent end users from running unapproved software on their computers.
• Run the latest version of your operating systems and applications. Deploy the latest security updates as soon as they become available.
• Use only official, trustworthy websites and direct download links.

ZLoader’s prevalence in the threat landscape demands comprehensive protection capable of detecting and stopping this malware, its components, and other similar threats at every stage of the attack chain. Microsoft Defender for Endpoint provides next-generation protection that reinforces network security perimeters and incorporates antimalware capabilities to catch emerging threats, including ZLoader, Cobalt Strike, additional payloads such as ransomware, and subsequent attacker behaviors. Moreover, our endpoint detection and response (EDR) capabilities detect ZLoader’s malicious files, behaviors, domain connections, and other related events before and after execution.

Defenders can further apply the following mitigations to reduce the environmental attack surface and mitigate the impact of this threat and its payloads:

• Configure Microsoft Defender for Office 365 to recheck links on click. Safe Links provides URL scanning and rewriting of inbound email messages in mail flow, and time-of-click verification of URLs and links in email messages and other locations. Safe Links scanning occurs in addition to the regular anti-spam and anti-malware protection in inbound email messages in Exchange Online Protection (EOP). Safe Links scanning can help protect your organization from malicious links that are used in phishing and other attacks.
• Configure Microsoft Defender for Office 365 to detonate file attachments via Safe Attachments. Safe Attachments provides an additional layer of protection for email attachments by verifying a file in a virtual environment prior to delivering to the inbox.
• Check your Office 365 antispam policy and your mail flow rules for allowed senders, domains and IP addresses. Apply extra caution when using these settings to bypass antispam filters, even if the allowed sender addresses are associated with trusted organizations—Office 365 will honor these settings and can let potentially harmful messages pass through. Review system overrides in threat explorer to determine why attack messages have reached recipient mailboxes.
• Configure Exchange Online to enable zero-hour auto purge (ZAP) in response to newly acquired threat intelligence. ZAP retroactively detects and neutralizes malicious phishing, spam, or malware messages that have already been delivered to mailboxes.
• Turn on network protection to block connections to malicious domains and IP addresses.
• Turn on tamper protection features to prevent attackers from stopping security services.
• Turn on cloud-delivered protection and automatic sample submission on Microsoft Defender Antivirus. These capabilities use artificial intelligence and machine learning to quickly identify and stop new and unknown threats.
• Turn on the following attack surface reduction rules to block or audit activity associated with this threat:
  • Block executable files from running unless they meet a prevalence, age, or trusted list criterion
  • Block all Office applications from creating child processes
  • Block Office applications from creating executable content
  • Block executable content from email client and webmail
  • Block Office applications from injecting code into other processes
  • Block credential stealing from the Windows local security authority subsystem (lsass.exe)
  • Block process creations originating from PsExec and WMI commands
  • Use advanced protection against ransomware
  • Block JavaScript or VBScript from launching downloaded executable content
  • Block execution of potentially obfuscated scripts

Appendix

Microsoft 365 Defender detections

Microsoft Defender Antivirus

Microsoft Defender Antivirus detects threat components as the following malware:

• Trojan:Win64/ZLoader
• Trojan:Win32/ZLoader

Shared malware and generic detections

Microsoft Defender Antivirus incorporates next-generation antivirus capabilities, including machine learning and behavioral detection. This can result in overlapping detections, particularly of first-seen components and polymorphic variants. The detection names are listed here for reference, but related alerts are not actively monitored.

Instances of Cobalt Strike use can be detected as the following:

• Bynoco – Cobalt Strike
• Atosev – Cobalt Strike
• Cosipor – Cobalt Strike

Microsoft Defender for Endpoint EDR

Alerts with the following titles in the security center can indicate threat activity on your network:

• Suspicious behavior associated with ZLoader
• File associated with ZLoader
• Connection to a domain associated with ZLoader

The following alerts might also indicate activity associated with this threat. However, unrelated threat activity can trigger these alerts.

• Microsoft Defender Antivirus protection turned off
• Suspicious Microsoft Defender Antivirus exclusion
• ZLoader’ malware was detected
• Suspicious behavior by cmd.exe was observed
• Suspicious PowerShell command line
• Suspicious Remote System Discovery
• Suspicious Domain Trust Discovery

Microsoft Defender for Office 365

Signals from Microsoft Defender for Office 365 inform Microsoft 365 Defender, which correlates cross-domain threat intelligence to deliver coordinated defense, that ZLoader has been detected when a document is delivered via email when detonation is enabled. These alerts, however, can also be triggered by unrelated threat activity.

• A potentially malicious URL click was detected
• Email messages containing malicious file removed after delivery​
• Email messages containing malicious URL removed after delivery​
• Email messages containing malware removed after delivery
• Email messages removed after delivery​
• Malware campaign detected after delivery
• Malware campaign detected and blocked
• Malware not zapped because ZAP is disabled

Hunting queries

Microsoft 365 Defender

To locate possible exploitation activity, run the following queries:

ZLoader alert activity

Surface devices with ZLoader alerts and related malicious activity.

/ Get any devices with ZLoader related Alert Activity
let DeviceAlerts = AlertInfo
| where Title in~('Suspicious behavior associated with ZLoader',
'File associated with ZLoader',
'Connection to a domain associated with ZLoader')
// Join in evidence information
| join AlertEvidence on AlertId
| where DeviceId != ""
| summarize by DeviceId, Title;
// Get additional alert activity for each device
AlertEvidence
| where DeviceId in(DeviceAlerts)
// Add additional info
| join kind=leftouter AlertInfo on AlertId
| summarize DeviceAlerts = make_set(Title), AlertIDs = make_set(AlertId) by DeviceId, bin(Timestamp, 1d)

MSHTA-loading DLLs

Look for instances of MSHTA loading suspicious DLL files.

DeviceProcessEvents
| where not(FileName has_any("certutil", "certutil32")) and FileName endswith ".exe" and ProcessVersionInfoFileDescription =~ "certutil.exe"
| where not(FolderPath has_any("installer", "program files"))

Suspicious registry keys

Look for registry keys created by the fraudulent, attacker-created companies used in this campaign.

DeviceRegistryEvents
| where RegistryValueData in('Flyintellect Inc.', 'Datalyst ou')

Malicious .bat file created in fake Oracle Java SE folder path

Look for .bat files created in the Oracle Java SE file path associated with this activity.

DeviceFileEvents
| where FileName endswith '.bat'
    and FolderPath has @'Program Files (x86)Sun Technology NetworkOracle Java SE'

Tim.exe payload delivery

Look for the Tim.exe payload being downloaded onto an affected device.

DeviceNetworkEvents
| where InitiatingProcessFileName =~ 'powershell.exe'
    and InitiatingProcessCommandLine has('Invoke-WebRequest') and InitiatingProcessCommandLine endswith '-OutFile tim.EXE'

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