Microsoft assesses that credentials acquired from CovertNetwork-1658 password spray operations are used by multiple Chinese threat actors. In particular, Microsoft has observed the Chinese threat actor Storm-0940 using credentials from CovertNetwork-1658. Active since at least 2021, Storm-0940 obtains initial access through password spray and brute-force attacks, or by exploiting or misusing network edge applications and services. Storm-0940 is known to target organizations in North America and Europe, including think tanks, government organizations, non-governmental organizations, law firms, defense industrial base, and others.

As with any observed nation-state threat actor activity, Microsoft has directly notified targeted or compromised customers, providing them with important information needed to help secure their environments. In this blog, we provide more information about CovertNetwork-1658 infrastructure, and associated Storm-0940 activity. We also share mitigation recommendations, detection information, and hunting queries that can help organizations identify, investigate, and mitigate associated activity.

What is CovertNetwork-1658?

Microsoft tracks a network of compromised small office and home office (SOHO) routers as CovertNetwork-1658. SOHO routers manufactured by TP-Link make up most of this network. Microsoft uses “CovertNetwork” to refer to a collection of egress IPs consisting of compromised or leased devices that may be used by one or more threat actors.

CovertNetwork-1658 specifically refers to a collection of egress IPs that may be used by one or more Chinese threat actors and is wholly comprised of compromised devices. Microsoft assesses that a threat actor located in China established and maintains this network. The threat actor exploits a vulnerability in the routers to gain remote code execution capability. We continue to investigate the specific exploit by which this threat actor compromises these routers. Microsoft assesses that multiple Chinese threat actors use the credentials acquired from CovertNetwork-1658 password spray operations to perform computer network exploitation (CNE) activities.

Post-compromise activity on compromised routers

After successfully gaining access to a vulnerable router, in some instances, the following steps are taken by the threat actor to prepare the router for password spray operations:

1. Download Telnet binary from a remote File Transfer Protocol (FTP) server
2. Download xlogin backdoor binary from a remote FTP server
3. Utilize the downloaded Telnet and xlogin binaries to start an access-controlled command shell on TCP port 7777
4. Connect and authenticate to the xlogin backdoor listening on TCP port 7777
5. Download a SOCKS5 server binary to router
6. Start SOCKS5 server on TCP port 11288

CovertNetwork-1658 is observed conducting their password spray campaigns through this proxy network to ensure the password spray attempts originate from the compromised devices.

Password spray activity from CovertNetwork-1658 infrastructure

Microsoft has observed multiple password spray campaigns originating from CovertNetwork-1658 infrastructure. In these campaigns, CovertNetwork-1658 submits a very small number of sign-in attempts to many accounts at a target organization. In about 80 percent of cases, CovertNetwork-1658 makes only one sign-in attempt per account per day. Figure 2 depicts this distribution in greater detail.

CovertNetwork-1658 infrastructure is difficult to monitor due to the following characteristics:

• The use of compromised SOHO IP addresses
• The use of a rotating set of IP addresses at any given time. The threat actors had thousands of available IP addresses at their disposal. The average uptime for a CovertNetwork-1658 node is approximately 90 days.
• The low-volume password spray process; for example, monitoring for multiple failed sign-in attempts from one IP address or to one account will not detect this activity

Various security vendors have reported on CovertNetwork-1658 activities, including Sekoia (July 2024) and Team Cymru (August 2024). Microsoft assesses that after these blogs were published, the usage of CovertNetwork-1658 network has declined substantially. The below chart highlights a steady and steep decline in the use of CovertNetwork-1658’s original infrastructure since their activities have been exposed in public reporting as observed in Censys.IO data.

Microsoft assesses that CovertNetwork-1658 has not stopped operations as indicated in recent activity but is likely acquiring new infrastructure with modified fingerprints from what has been publicly disclosed. An observed increase in recent activity may be early evidence supporting this assessment.

Historically, Microsoft has observed an average of 8,000 compromised devices actively engaged in the CovertNetwork-1658 network at any given time. On average, about 20 percent of these devices perform password spraying at any given time. Any threat actor using the CovertNetwork-1658 infrastructure could conduct password spraying campaigns at a larger scale and greatly increase the likelihood of successful credential compromise and initial access to multiple organizations in a short amount of time. This scale, combined with quick operational turnover of compromised credentials between CovertNetwork-1658 and Chinese threat actors, allows for the potential of account compromises across multiple sectors and geographic regions.

Below are User Agent Strings* observed in the password spray activity:

• Mozilla/5.0 (Windows NT 10.0; WOW64; Trident/7.0; rv:11.0) like Gecko
• Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/80.0.3987.149 Safari/537.36

*Note: We updated this list of User Agent Strings on November 4, 2024 to fix typos.

Observed activity tied to Storm-0940

Microsoft has observed numerous cases where Storm-0940 has gained initial access to target organizations using valid credentials obtained through CovertNetwork-1658’s password spray operations. In some instances, Storm-0940 was observed using compromised credentials that were obtained from CovertNetwork-1658 infrastructure on the same day. This quick operational hand-off of compromised credentials is evidence of a likely close working relationship between the operators of CovertNetwork-1658 and Storm-0940.

After successfully gaining access to a victim environment, in some instances, Storm-0940 has been observed:        

• Using scanning and credential dumping tools to move laterally within the network;
• Attempting to access network devices and install proxy tools and remote access trojans (RATs) for persistence; and
• Attempting to exfiltrate data.

Recommendations

Organizations can defend against password spraying by building credential hygiene and hardening cloud identities. Microsoft recommends the following mitigations to reduce the impact of this threat:

• Educate users on the importance of credential hygiene and avoiding password reuse.
• Enforce multi-factor authentication (MFA) on all accounts, remove users excluded from MFA, and strictly require MFA from all devices, in all locations, at all times. Microsoft continues to expand MFA defaults for products and services like Azure to broaden MFA adoption.
  • Consider transitioning to a passwordless primary authentication method, such as Azure MFA, certificates, or Windows Hello for Business.
  • Secure Remote Desktop Protocol (RDP) or Windows Virtual Desktop endpoints with MFA to harden against password spray or brute force attacks.
• 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.
• Use a cloud-based identity security solution to identify and detect threats or compromised identities.
• Disable stale or unused accounts.
• Reset account passwords for any accounts targeted during a password spray attack. If a targeted account had system-level permissions, further investigation may be warranted.
• Implement the Azure Security Benchmark and general best practices for securing identity infrastructure, including:
  • Create conditional access policies to allow or disallow access to the environment based on defined criteria.
• • Block legacy authentication with Azure AD by using Conditional Access. Legacy authentication protocols don’t have the ability to enforce MFA, so blocking such authentication methods will prevent password spray attackers from taking advantage of the lack of MFA on those protocols.
  • Enable AD FS web application proxy extranet lockout to protect users from potential password brute force compromise.
• Secure accounts with credential hygiene:
  • Practice the principle of least privilege and audit privileged account activity in your Azure AD environments to slow and stop attackers.
  • Deploy Azure AD Connect Health for ADFS. This captures failed attempts as well as IP addresses recorded in ADFS logs for bad requests via the Risky IP report.
  • Use Azure AD password protection to detect and block known weak passwords and their variants.
  • Turn on identity protection in Azure AD to monitor for identity-based risks and create policies for risky sign ins.
• Educate users about phishing attempts and MFA fatigue attacks. Encourage users to report unsolicited MFA authentication prompts.
• Review your Anomaly detection policies in Defender for Cloud Apps under Microsoft 365 Defender Policies by going to Cloud Apps > Policies > Policy management. Then select Anomaly detection policy.

Detection details

Alerts with the following titles in the Security Center can indicate threat activity on your network:

Microsoft Defender for Endpoint

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

• Storm-0940 actor activity detected

Microsoft Defender XDR

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

• Password spray attacks originating from single ISP

Microsoft Defender for Identity

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

• Password Spray
• Unfamiliar Sign-in properties
• Atypical travel
• Suspicious behavior: Impossible travel activity

Microsoft Defender for Cloud Apps

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

• Suspicious Administrative Activity
• Impossible travel activity

Hunting queries

Microsoft Defender XDR

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

Potential Storm-0940 activity           

This query identifies UserAgents obtained from observed activity and AAD SignInEvent attributes that identify potential activity to guide investigation:

//Advanced Hunting Query
let suspAppRes = datatable(appId:string, resourceId:string)
[
    "1950a258-227b-4e31-a9cf-717495945fc2", "00000003-0000-0000-c000-000000000000"
];
let userAgents = datatable(userAgent:string)
[
    "Mozilla/5.0 (Windows NT 10.0; WOW64; Trident/7.0; rv:11.0) like Gecko",
    "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/80.0.3987.149 Safari/537.36" //Low fidelity
];
AADSignInEventsBeta
| where Timestamp >=ago(30d)
| where ApplicationId in ((suspAppRes | project appId)) and ResourceId in ((suspAppRes | project resourceId)) and UserAgent in ((userAgents| project userAgent))
Failed sign-in activity
The following query identifies failed attempts to sign-in from multiple sources that originate from a single ISP. Attackers distribute attacks from multiple IP addresses across a single service provider to evade detection
IdentityLogonEvents
| where Timestamp > ago(4h)
| where ActionType == "LogonFailed"
| where isnotempty(AccountObjectId)
| summarize TargetCount = dcount(AccountObjectId), TargetCountry = dcount(Location), TargetIPAddress = dcount(IPAddress) by ISP
| where TargetCount >= 100
| where TargetCountry >= 5
| where TargetIPAddress >= 25

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. More details on the Content Hub can be found here: https://learn.microsoft.com/azure/sentinel/sentinel-solutions-deploy.

Potential Storm-0940 activity

This query identifies UserAgents obtained from observed activity and AAD SignInEvent attributes that identify potential activity to guide investigation:

//sentinelquery
let suspAppRes = datatable(appId:string, resourceId:string)
[
    "1950a258-227b-4e31-a9cf-717495945fc2", "00000003-0000-0000-c000-000000000000"
];
let userAgents = datatable(userAgent:string)
[
    "Mozilla/5.0 (Windows NT 10.0; WOW64; Trident/7.0; rv:11.0) like Gecko",
    "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/80.0.3987.149 Safari/537.36" //Low fidelity
];
SigninLogs
| where TimeGenerated >=ago(30d)
| where AppId  in ((suspAppRes | project appId)) and ResourceIdentity in ((suspAppRes | project resourceId)) and UserAgent in ((userAgents| project userAgent))

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, and on X (formerly Twitter) at https://twitter.com/MsftSecIntel.

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 Chinese threat actor Storm-0940 uses credentials from password spray attacks from a covert network appeared first on Microsoft Security Blog.

The spear-phishing emails in this campaign were sent to thousands of targets in over 100 organizations and contained a signed Remote Desktop Protocol (RDP) configuration file that connected to an actor-controlled server. In some of the lures, the actor attempted to add credibility to their malicious messages by impersonating Microsoft employees. The threat actor also referenced other cloud providers in the phishing lures.

While this campaign focuses on many of Midnight Blizzard’s usual targets, the use of a signed RDP configuration file to gain access to the targets’ devices represents a novel access vector for this actor. Overlapping activity has also been reported by the Government Computer Emergency Response Team of Ukraine (CERT-UA) under the designation UAC-0215 and also by Amazon.

Midnight Blizzard is a Russian threat actor attributed by the United States and United Kingdom governments to the Foreign Intelligence Service of the Russian Federation, also known as the SVR. This threat actor is known to primarily target governments, diplomatic entities, non-governmental organizations (NGOs), and IT service providers, primarily in the United States and Europe. Its focus is to collect intelligence through longstanding and dedicated espionage of foreign interests that can be traced to early 2018. Its operations often involve compromise of valid accounts and, in some highly targeted cases, advanced techniques to compromise authentication mechanisms within an organization to expand access and evade detection.

Midnight Blizzard is consistent and persistent in its operational targeting, and its objectives rarely change. It uses diverse initial access methods, including spear phishing, stolen credentials, supply chain attacks, compromise of on-premises environments to laterally move to the cloud, and leveraging service providers’ trust chain to gain access to downstream customers. Midnight Blizzard is known to use the Active Directory Federation Service (AD FS) malware known as FOGGYWEB and MAGICWEB. Midnight Blizzard is identified by peer security vendors as APT29, UNC2452, and Cozy Bear.

As with any observed nation-state actor activity, Microsoft is in the process of directly notifying customers that have been targeted or compromised, providing them with the necessary information to secure their accounts. Strong anti-phishing measures will help to mitigate this threat. As part of our commitment to helping protect against cyber threats, we provide indicators of compromise (IOCs), hunting queries, detection details, and recommendations at the end of this post.

Spear-phishing campaign

On October 22, 2024, Microsoft identified a spear-phishing campaign in which Midnight Blizzard sent phishing emails to thousands of users in over 100 organizations. The emails were highly targeted, using social engineering lures relating to Microsoft, Amazon Web Services (AWS), and the concept of Zero Trust. The emails contained a Remote Desktop Protocol (RDP) configuration file signed with a LetsEncrypt certificate. RDP configuration (.RDP) files summarize automatic settings and resource mappings that are established when a successful connection to an RDP server occurs. These configurations extend features and resources of the local system to a remote server, controlled by the actor.

In this campaign, the malicious .RDP attachment contained several sensitive settings that would lead to significant information exposure. Once the target system was compromised, it connected to the actor-controlled server and bidirectionally mapped the targeted user’s local device’s resources to the server. Resources sent to the server may include, but are not limited to, all logical hard disks, clipboard contents, printers, connected peripheral devices, audio, and authentication features and facilities of the Windows operating system, including smart cards. This access could enable the threat actor to install malware on the target’s local drive(s) and mapped network share(s), particularly in AutoStart folders, or install additional tools such as remote access trojans (RATs) to maintain access when the RDP session is closed. The process of establishing an RDP connection to the actor-controlled system may also expose the credentials of the user signed in to the target system.

RDP connection

When the target user opened the .RDP attachment, an RDP connection was established to an actor-controlled system. The configuration of the RDP connection then allowed the actor-controlled system to discover and use information about the target system, including:

• Files and directories
• Connected network drives
• Connected peripherals, including smart cards, printers, and microphones
• Web authentication using Windows Hello, passkeys, or security keys
• Clipboard data
• Point of Service (also known as Point of Sale or POS) devices

Targets

Microsoft has observed this campaign targeting governmental agencies, higher education, defense, and non-governmental organizations in dozens of countries, but particularly in the United Kingdom, Europe, Australia, and Japan. This target set is consistent with other Midnight Blizzard phishing campaigns.

Email infrastructure

Midnight Blizzard sent the phishing emails in this campaign using email addresses belonging to legitimate organizations that were gathered during previous compromises. The domains used are listed in the IOC section below.

Mitigations

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

Strengthen operating environment configuration

• Utilize Windows Firewall or Windows Firewall with Advanced Security to help prevent or restrict outbound RDP connection attempts to external or public networks external or public networks
• Require multifactor authentication (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 number matching. Avoid telephony-based MFA methods to avoid risks associated with SIM-jacking.
• Implement Conditional Access authentication strength to require phishing-resistant authentication for employees and external users for critical apps.
• Encourage users to use Microsoft Edge and other web browsers that support Microsoft Defender SmartScreen, which identifies and help blocks malicious websites, including phishing sites, scam sites, and sites that host malware.

Strengthen endpoint security configuration

If you are using Microsoft Defender for Endpoint take the following steps:

• Ensure tamper protection is turned on in Microsoft Defender for Endpoint.
• Turn on 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 help 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 help 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 help resolve breaches, significantly reducing alert volume. 
• Microsoft Defender XDR customers can turn on the following attack surface reduction rules to help prevent common attack techniques used by threat actors.
  • Block executable content from email client and webmail
  • Block executable files from running unless they meet a prevalence, age, or trusted list criterion

Strengthen antivirus configuration

• Turn on cloud-delivered protection in Microsoft Defender Antivirus, or the equivalent for your antivirus product, to help cover rapidly evolving attacker tools and techniques. Cloud-based machine learning protections help block a majority of new and unknown variants.
• Enable Microsoft Defender Antivirus scanning of downloaded files and attachments.
• Enable Microsoft Defender Antivirus real-time protection.

Strengthen Microsoft Office 365 configuration

• Turn on Safe Links and Safe Attachments for Office 365.
• Enable Zero-hour auto purge (ZAP) in Office 365 to help quarantine sent mail in response to newly acquired threat intelligence and retroactively neutralize malicious phishing, spam, or malware messages that have already been delivered to mailboxes.

Strengthen email security configuration

• Invest in advanced anti-phishing solutions that monitor incoming emails and visited websites. For example, Microsoft Defender for Office 365 merges incident and alert management across email, devices, and identities, centralizing investigations for email-based threats. Organizations can also leverage web browsers that automatically identify and help block malicious websites, including those used in phishing activities.
• If you are using Microsoft Defender for Office 365, configure it 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, other Microsoft 365 applications such as Teams, and other locations such as SharePoint Online. Safe Links scanning occurs in addition to the regular anti-spam and anti-malware protection in inbound email messages in Microsoft Exchange Online Protection (EOP). Safe Links scanning can help protect an organization from malicious links used in phishing and other attacks.
• If you are using Microsoft Defender for Office 365, use the Attack Simulator in Microsoft Defender for Office 365 to run realistic, yet safe, simulated phishing and password attack campaigns. Run spear-phishing (credential harvest) simulations to train end-users against clicking URLs in unsolicited messages and disclosing credentials.

Conduct user education

• Robust user education can help mitigate the threat of social engineering and phishing emails. Companies should have a user education program that highlights how to identify and report suspicious emails.

Microsoft Defender XDR detections

Microsoft Defender for Endpoint

The following alerts may 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.

• Midnight Blizzard Actor activity group
• Suspicious RDP session

Microsoft Defender Antivirus

Microsoft Defender Antivirus detects at least some of the malicious .RDP files as the following signature:

• Backdoor:Script/HustleCon.A

Microsoft Defender for Cloud

The following alerts may 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.

• Communication with suspicious domain identified by threat intelligence
• Suspicious outgoing RDP network activity
• Traffic detected from IP addresses recommended for blocking

Microsoft Defender for Office 365

Microsoft Defender for Office 365 raises alerts on this campaign using email- and attachment-based detections. Additionally, hunting signatures and an RDP file parser have been incorporated into detections to block similar campaigns in the future. Defenders can identify such activity in alert titles referencing RDP, for example, Trojan_RDP*.

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 threat intelligence, protection information, and recommended actions to prevent, mitigate, or respond to associated threats found in customer environments.

Microsoft Defender Threat Intelligence

• Midnight Blizzard targets NGOs in new wave of initial access campaigns.
• Midnight Blizzard targets diplomatic, NGOs, and humanitarian organizations in global spear phishing activity.

Hunting queries

Microsoft Defender XDR

Identify potential Midnight Blizzard targeted recipients 

Surface possible targeted email accounts within the environment where the email sender originated from a Midnight Blizzard compromised domain related to the RDP activity.

EmailEvents 
| where SenderFromDomain in~ ("sellar.co.uk", "townoflakelure.com", "totalconstruction.com.au", "swpartners.com.au", "cewalton.com") 
| project SenderFromDomain, SenderFromAddress, RecipientEmailAddress, Subject, Timestamp 

Surface potential targets of an RDP attachment phishing attempt

Surface emails that contain a remote desktop protocol (RDP) file attached. This may indicate that the recipient of the email may have been targeted in an RDP attachment phishing attack attempt.

EmailAttachmentInfo
| where FileName has ".rdp"
| join kind=inner (EmailEvents) on NetworkMessageId
| project SenderFromAddress, RecipientEmailAddress, Subject, Timestamp, FileName, FileType

Identify potential successfully targeted assets in an RDP attachment phishing attack

Surface devices that may have been targeted in an email with an RDP file attached, followed by an RDP connection attempt from the device to an external network. This combined activity may indicate that a device may have been successfully targeted in an RDP attachment phishing attack.

// Step 1: Identify emails with RDP attachments
let rdpEmails = EmailAttachmentInfo
| where FileName has ".rdp"
| join kind=inner (EmailEvents) on NetworkMessageId
| project EmailTimestamp = Timestamp, RecipientEmailAddress, NetworkMessageId, SenderFromAddress;
// Step 2: Identify outbound RDP connections
let outboundRDPConnections = DeviceNetworkEvents
| where RemotePort == 3389
| where ActionType == "ConnectionAttempt"
| where RemoteIPType == "Public"
| project RDPConnectionTimestamp = Timestamp, DeviceId, InitiatingProcessAccountUpn, RemoteIP;
// Step 3: Correlate email and network events
rdpEmails
| join kind=inner (outboundRDPConnections) on $left.RecipientEmailAddress == $right.InitiatingProcessAccountUpn
| project EmailTimestamp, RecipientEmailAddress, SenderFromAddress, RDPConnectionTimestamp, DeviceId, RemoteIP

Threat actor RDP connection files attached to email

Surface users that may have received an RDP connection file attached in email that have been observed in this attack from Midnight Blizzard.

EmailAttachmentInfo
| where FileName in~ (
    "AWS IAM Compliance Check.rdp",
    "AWS IAM Configuration.rdp",
    "AWS IAM Quick Start.rdp",
    "AWS SDE Compliance Check.rdp",
    "AWS SDE Environment Check.rdp",
    "AWS Secure Data Exchange - Compliance Check.rdp",
    "AWS Secure Data Exchange Compliance.rdp",
    "Device Configuration Verification.rdp",
    "Device Security Requirements Check.rdp",
    "IAM Identity Center Access.rdp",
    "IAM Identity Center Application Access.rdp",
    "Zero Trust Architecture Configuration.rdp",
    "Zero Trust Security Environment Compliance Check.rdp",
    "ZTS Device Compatibility Test.rdp"
)
| project Timestamp, FileName, SHA256, RecipientEmailAddress, SenderDisplayName, SenderFromAddress

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.

Indicators of compromise

Email sender domains

RDP file names

• AWS IAM Compliance Check.rdp
• AWS IAM Configuration.rdp
• AWS IAM Quick Start.rdp
• AWS SDE Compliance Check.rdp
• AWS SDE Environment Check.rdp
• AWS SDE Environment Check.rdp 
• AWS Secure Data Exchange – Compliance Check.rdp
• AWS Secure Data Exchange Compliance.rdp
• Device Configuration Verification.rdp
• Device Security Requirements Check.rdp
• IAM Identity Center Access.rdp
• IAM Identity Center Application Access.rdp
• Zero Trust Architecture Configuration.rdp
• Zero Trust Security Environment Compliance Check.rdp
• ZTS Device Compatibility Test.rdp

RDP remote computer domains

References

• https://cert.gov.ua/article/6281076
• https://aws.Alpha XR/blogs/security/amazon-identified-internet-domains-abused-by-apt29/
• https://media.defense.gov/2024/Oct/09/2003562611/-1/-1/0/CSA-UPDATE-ON-SVR-CYBER-OPS.PDF
• http://approjects.co.za/?big=security/blog/2021/09/27/foggyweb-targeted-nobelium-malware-leads-to-persistent-backdoor/?msockid=392e4194f0f26165030055c3f1de6080
• http://approjects.co.za/?big=security/blog/2022/08/24/magicweb-nobeliums-post-compromise-trick-to-authenticate-as-anyone/?msockid=392e4194f0f26165030055c3f1de6080

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, and on X (formerly Twitter) at https://twitter.com/MsftSecIntel.

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 Midnight Blizzard conducts large-scale spear-phishing campaign using RDP files appeared first on Microsoft Security Blog.

After discovering the bypass technique, we shared our findings with Apple through Coordinated Vulnerability Disclosure (CVD) via Microsoft Security Vulnerability Research (MSVR). Apple released a fix for this vulnerability, now identified as CVE-2024-44133, as part of security updates for macOS Sequoia, released on September 16, 2024. At present, only Safari uses the new protections afforded by TCC. Microsoft is currently collaborating with other major browser vendors to investigate the benefits of hardening local configuration files.

We encourage macOS users to apply these security updates as soon as possible. Behavior monitoring protections in Microsoft Defender for Endpoint has detected activity associated with Adload, a prevalent macOS threat family, potentially exploiting this vulnerability. Microsoft Defender for Endpoint detects and blocks CVE-2024-44133 exploitation, including anomalous modification of the Preferences file through HM Surf or other methods.

We initially described TCC technology and how we were able to bypass it in our powerdir vulnerability discovery. As a reminder, TCC is a technology that prevents apps from accessing users’ personal information, including services such as location services, camera, microphone, downloads directory, and others, without their prior consent and knowledge. Formally, the only legitimate way for an app to gain access to those services is by approving a popup through the user interface, or by approving per-app access in the operating system’s settings. In this blog post, we share details on how HM Surf can enable attackers to bypass TCC and access the said services without user consent. We also provide guidance for organizations to protect devices from successful exploitation.

Safari entitlements and TCC

Entitlements, as we shared in a past blog post, are privileges that macOS apps might have, and are digitally signed by Apple. Apple reserves some entitlements to their own applications, which are known as private entitlements. Such entitlements commonly start with the com.apple.private prefix.

When it comes to TCC, the com.apple.private.tcc.allow entitlement allows the entitled app to completely bypass TCC checks for services that are mentioned under the entitlement. Safari, the default browser in macOS, has very powerful TCC entitlements, including com.apple.private.tcc.allow:

There are two important aspects here:

1. Safari can freely access the address book (kTCCServiceAddressBook), camera (kTCCServiceCamera), microphone (kTCCServiceMicrophone), and more, completely bypassing TCC access checks for those services.
2. Safari is compiled with flags=0x2000 (library-validation), which means all dynamically loaded libraries must be digitally signed by the same Team ID. This feature could be considered a part of Apple’s Hardened Runtime, and hardens the app against certain type of attacks such as code injection. The Hardened Runtime technology is in many aspects similar to the Windows process mitigation policies, and essentially means an attacker is going to have a very hard time running arbitrary code in the context of Safari.

By default, when one browses a website that requires access to the camera or the microphone, a TCC-like popup still appears, which means Safari maintains its own TCC policy. That makes sense, since Safari must maintain access records on a per-origin (website) basis:

We discovered that Safari maintains its configuration in various files under ~/Library/Safari (the user’s home directory). That said directory contains several files of interest, including the following:

Therefore:

1. Reading arbitrary files from the directory allows attackers to gather extremely useful information (such as the user’s browsing history).
2. Writing to the directory allows TCC bypasses, for instance, by overriding the PerSitePreferences.db.

Apple’s approach of protecting that directory with TCC is therefore very justified.

Exploitation

Similar to the exploit we developed for powerdir, we noticed that sensitive files exist under the user’s home directory. We concluded we could use a similar method to remove the protection for the ~/Library/Safari directory.

Our exploit involves the following steps:

1. Change the home directory of the current user with the dscl utility, which does not require TCC access in Sonoma (At this point, the ~/Library/Safari directory is no longer TCC protected).
2. Modify the sensitive files under the user’s real home directory (such as /Users/$USER/Library/Safari/PerSitePreferences.db).
3. Change the home directory again so Safari uses the now modified files.
4. Run Safari to open a webpage that takes a camera snapshot and trace device location.

In our exploit, we also reset the TCC permissions of the Terminal (using tccutil) for the sake of demonstration.

We noticed that PerSitePreferences.db is used only when a secure connection occurs (over HTTPS), but an attacker could host malicious JavaScript code over HTTPS.

The JavaScript code that takes the camera snapshot and retrieves location information is straightforward and is hosted here (the code does not include the exploit). The most important part that usually requires TCC camera access is:

We downloaded the snapshot in our demonstration, but in a real scenario, an attacker could do stealthy things, including:

1. Host the snapshot somewhere to be downloaded later privately.
2. Save an entire camera stream.
3. Record microphone and stream it to another server or upload it.
4. Get access to the device’s location.
5. Start Safari in a very small window to not draw attention.

We called our exploit HM Surf in reference to the HM03 (Surf) Safari zone and recorded a complete video of our exploit. Note how TCC access for Camera is not permitted, as well as Safari-specific controls do not automatically allow Camera access:

Third-party browsers

Third-party browsers such as Google Chrome, Mozilla Firefox, or Microsoft Edge do not have the same private entitlements as Apple applications, which means that the said apps can’t bypass TCC checks.

Therefore, when an end-user runs a third-party browser to use a TCC service (such as the camera, microphone, or location) for the first time, a TCC popup will appear and ask for access to the resource. By design, the access approval happens at the app level rather than at a per-origin (the combination of schema, host name, and port number) level. Once access is approved to an app, it’s then up to that app to maintain their own database of approved origins for privacy and safety.

Detecting new Adload behavior via behavioral monitoring

After discovering this new technique of bypassing TCC, we deployed behavior monitoring detection strategies to protect customers. In analyzing the intelligence gathered from the detection strategies, we observed a suspicious activity in a customer’s device: a process by the name of p running from the /private/tmp world-writable folder (SHA-256: 17e1b83089814128bc243315894f412026503c10b710c9c59d4aaf67bc209cb8) that anomalously modified the local user’s Chrome Preferences file.

Upon further examination, we discovered the parent process was running with the following command line:

/Users/<username>/Library/Application Support/.17066225541972342347/Services/com.BasicIndex.service/BasicIndex.service” -s 6600

The com.BasicIndex.service folder name is a fake macOS service attributed to Adload, a prevalent macOS threat family we have described in the past.

These are the behaviors we discovered:

Since we weren’t able to observe the steps taken leading to the activity, we can’t fully determine if the Adload campaign is exploiting the HM surf vulnerability itself. Attackers using a similar method to deploy a prevalent threat raises the importance of having protection against attacks using this technique.

Microsoft Defender for Endpoint uses advanced behavioral analytics and machine learning to detect anomalous activities on a device and can detect this kind of malicious behavior, including anomalous modification of the Preferences file through HM Surf or other methods.

Hardening device security through vulnerability management and behavioral monitoring

Continuous research on vulnerabilities in security technologies like TCC in macOS devices is important to help ensure that user data is protected from unauthorized access. Software vendors are always in a tight race against malicious actors to discover vulnerabilities and address them before they are exploited for attacks. The discoveries and insights from our research, including vulnerabilities such as Migraine, powerdir, and Shrootless, enrich our protection technologies and solutions such as Microsoft Defender for Endpoint, which allows organizations to quickly discover and remediate vulnerabilities in their networks that are increasingly becoming heterogeneous.

In addition, Microsoft Defender for Endpoint uses advanced behavioral analytics and machine learning to detect anomalous activities on a device, such as creating spoofed home directories, a technique which was previously used in other vulnerabilities. In the example provided in the previous section, Microsoft Defender for Endpoint detects modifications to the Safari private directory, as well as private directories of third-party browsers, as suspicious. Extending the concept, Defender for Endpoint has similar detections for sensitive file access (including Safari-specific settings) by a non-Safari application.

Apple has also introduced new APIs for App Group Containers that make SIP (System Integrity Policy) that protect configuration files from being modified by an external attacker, resolving the vulnerability class. At present, only Safari uses the new protections afforded by TCC. Microsoft is currently collaborating with other major browser vendors to investigate the benefits of hardening local configuration files. While Chromium and Firefox is yet to adopt the new APIs, Chromium is moving towards using os_crypt which solves the attack in a different way.

Microsoft continues to monitor the threat landscape to discover new vulnerabilities and attacker techniques that could affect macOS and other non-Windows devices. As cross-platform threats continue to increase, a coordinated response to vulnerability discoveries and other forms of threat intelligence sharing will help enrich protection technologies that secure users’ computing experience regardless of the platform or device they’re using.

References

• https://developer.apple.com/documentation/security/hardened_runtime
• https://attack.mitre.org/techniques/T1055/
• https://ss64.com/mac/dscl.html
• https://ss64.com/mac/tccutil.html
• https://github.com/yo-yo-yo-jbo/hm-surf/blob/main/hm-surf.html
• https://bulbapedia.bulbagarden.net/wiki/HM03

Jonathan Bar Or
Microsoft Threat Intelligence

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, and on X (formerly Twitter) at https://twitter.com/MsftSecIntel.

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 New macOS vulnerability, “HM Surf”, could lead to unauthorized data access appeared first on Microsoft Security Blog.

Education is essentially an “industry of industries,” with K-12 and higher education enterprises handling data that could include health records, financial data, and other regulated information. At the same time, their facilities can host payment processing systems, networks that are used as internet service providers (ISPs), and other diverse infrastructure. The cyberthreats that Microsoft observes across different industries tend to be compounded in education, and threat actors have realized that this sector is inherently vulnerable. With an average of 2,507 cyberattack attempts per week, universities are prime targets for malware, phishing, and IoT vulnerabilities.¹ 

Security staffing and IT asset ownership also affect education organizations’ cyber risks. School and university systems, like many enterprises, often face a shortage of IT resources and operate a mix of both modern and legacy IT systems. Microsoft observes that in the United States, students and faculty are more likely to use personal devices in education compared to Europe, for example. Regardless of ownership however, in these and other regions, busy users do not always have a security mindset. 

This edition of Cyber Signals delves into the cybersecurity challenges facing classrooms and campuses, highlighting the critical need for robust defenses and proactive measures. From personal devices to virtual classes and research stored in the cloud, the digital footprint of school districts, colleges, and universities has multiplied exponentially.  

We are all defenders. 

A uniquely valuable and vulnerable environment 

The education sector’s user base is very different from a typical large commercial enterprise. In the K-12 environment, users include students as young as six years old. Just like any public or private sector organization, there is a wide swath of employees in school districts and at universities including administration, athletics, health services, janitorial, food service professionals, and others. Multiple activities, announcements, information resources, open email systems, and students create a highly fluid environment for cyberthreats.

Virtual and remote learning have also extended education applications into households and offices. Personal and multiuser devices are ubiquitous and often unmanaged—and students are not always cognizant about cybersecurity or what they allow their devices to access.

Education is also on the front lines confronting how adversaries test their tools and their techniques. According to data from Microsoft Threat Intelligence, the education sector is the third-most targeted industry, with the United States seeing the greatest cyberthreat activity.

Cyberthreats to education are not only a concern in the United States. According to the United Kingdom’s Department of Science Innovation and Technology 2024 Cybersecurity Breaches Survey, 43% of higher education institutions in the UK reported experiencing a breach or cyberattack at least weekly.² 

QR codes provide an easily disguised surface for phishing cyberattacks

Today, quick response (QR) codes are quite popular—leading to increased risks of phishing cyberattacks designed to gain access to systems and data. Images in emails, flyers offering information about campus and school events, parking passes, financial aid forms, and other official communications all frequently contain QR codes. Physical and virtual education spaces might be the most “flyer friendly” and QR code-intensive environments anywhere, given how big a role handouts, physical and digital bulletin boards, and other casual correspondence help students navigate a mix of curriculum, institutional, and social correspondence. This creates an attractive backdrop for malicious actors to target users who are trying to save time with a quick image scan. 

Recently the United States Federal Trade Commission issued a consumer alert on the rising threat of malicious QR codes being used to steal login credentials or deliver malware.³

Microsoft Defender for Office 365 telemetry shows that approximately more than 15,000 messages with malicious QR codes are targeted toward the educational sector daily—including phishing, spam, and malware. 

Legitimate software tools can be used to quickly generate QR codes with embedded links to be sent in email or posted physically as part of a cyberattack. And those images are hard for traditional email security solutions to scan, making it even more important for faculty and students to use devices and browsers with modern web defenses. 

Targeted users in the education sector may use personal devices without endpoint security. QR codes essentially enable the threat actor to pivot to these devices. QR code phishing (since its purpose is to target mobile devices) is compelling evidence of mobile devices being used as an attack vector into enterprises—such as personal accounts and bank accounts—and the need for mobile device protection and visibility. Microsoft has significantly disrupted QR code phishing attacks. This shift in tactics is evident in the substantial decrease in daily phishing emails intercepted by our system, dropping from 3 million in December 2023 to just 179,000 by March 2024. 

Universities present their own unique challenges. Much of university culture is based on collaboration and sharing to drive research and innovation. Professors, researchers, and other faculty operate under the notion that technology, science—simply knowledge itself—should be shared widely. If someone appearing as a student, peer, or similar party reaches out, they’re often willing to discuss potentially sensitive topics without scrutinizing the source. 

University operations also span multiple industries. University presidents are effectively CEOs of healthcare organizations, housing providers, and large financial organizations—the industry of industries factor, again. Therefore, top leaders can can be prime targets for anyone attacking those sectors.

The combination of value and vulnerability found in education systems has attracted the attention of a spectrum of cyberattackers—from malware criminals employing new techniques to nation-state threat actors engaging in old-school spy craft.  

Microsoft continually monitors threat actors and threat vectors worldwide. Here are some key issues we’re seeing for education systems. 

Email systems in schools offer wide spaces for compromise 

The naturally open environment at most universities forces them to be more relaxed in their email hygiene. They have a lot of emails amounting to noise in the system, but are often operationally limited in where and how they can place controls, because of how open they need to be for alumni, donors, external user collaboration, and many other use cases.  

Education institutions tend to share a lot of announcements in email. They share informational diagrams around local events and school resources. They commonly allow external mailers from mass mailing systems to share into their environments. This combination of openness and lack of controls creates a fertile ground for cyberattacks.

AI is increasing the premium on visibility and control  

Cyberattackers recognizing higher education’s focus on building and sharing can survey all visible access points, seeking entry into AI-enabled systems or privileged information on how these systems operate. If on-premises and cloud-based foundations of AI systems and data are not secured with proper identity and access controls, AI systems become vulnerable. Just as education institutions adapted to cloud services, mobile devices and hybrid learning—which introduced new waves of identities and privileges to govern, devices to manage, and networks to segment—they must also adapt to the cyber risks of AI by scaling these timeless visibility and control imperatives.

Nation-state actors are after valuable IP and high-level connections 

Universities handling federally funded research, or working closely with defense, technology, and other industry partners in the private sector, have long recognized the risk of espionage. Decades ago, universities focused on telltale physical signs of spying. They knew to look for people showing up on campus taking pictures or trying to get access to laboratories. Those are still risks, but today the dynamics of digital identity and social engineering have greatly expanded the spy craft toolkit. 

Universities are often epicenters of highly sensitive intellectual property. They may be conducting breakthrough research. They may be working on high-value projects in aerospace, engineering, nuclear science, or other sensitive topics in partnership with multiple government agencies.  

For cyberattackers, it can be easier to first compromise somebody in the education sector who has ties to the defense sector and then use that access to more convincingly phish a higher value target.  

Universities also have experts in foreign policy, science, technology, and other valuable disciplines, who may willingly offer intelligence, if deceived in social-engineering cyberattacks employing false or stolen identities of peers and others who appear to be in individuals’ networks or among trusted contacts. Apart from holding valuable intelligence themselves, compromised accounts of university employees can become springboards into further campaigns against wider government and industry targets.

Nation-state actors targeting education 

Peach Sandstorm

Peach Sandstorm has used password spray attacks against the education sector to gain access to infrastructure used in those industries, and Microsoft has also observed the organization using social engineering against targets in higher education.  

Mint Sandstorm 

Microsoft has observed a subset of this Iranian attack group targeting high-profile experts working on Middle Eastern affairs at universities and research organizations. These sophisticated phishing attacks used social engineering to compel targets to download malicious files including a new, custom backdoor called MediaPl. 

Mabna Institute  

In 2023, the Iranian Mabna Institute conducted intrusions into the computing systems of at least 144 United States universities and 176 universities in 21 other countries.  

The stolen login credentials were used for the benefit of Iran’s Islamic Revolutionary Guard Corps and were also sold within Iran through the web. Stolen credentials belonging to university professors were used to directly access university library systems. 

Emerald Sleet

This North Korean group primarily targets experts in East Asian policy or North and South Korean relations. In some cases, the same academics have been targeted by Emerald Sleet for nearly a decade.  

Emerald Sleet uses AI to write malicious scripts and content for social engineering, but these attacks aren’t always about delivering malware. There’s also an evolving trend where they simply ask experts for policy insight that could be used to manipulate negotiations, trade agreements, or sanctions. 

Moonstone Sleet 

Moonstone Sleet is another North Korean actor that has been taking novel approaches like creating fake companies to forge business relationships with educational institutions or a particular faculty member or student.  

One of the most prominent attacks from Moonstone Sleet involved creating a fake tank-themed game used to target individuals at educational institutions, with a goal to deploy malware and exfiltrate data. 

Storm-1877  

This actor largely engages in cryptocurrency theft using a custom malware family that they deploy through various means. The ultimate goal of this malware is to steal crypto wallet addresses and login credentials for crypto platforms.  

Students are often the target for these attacks, which largely start on social media. Storm-1877 targets students because they may not be as aware of digital threats as professionals in industry. 

A new security curriculum 

Due to education budget and talent constraints and the inherent openness of its environment, solving education security is more than a technology problem. Security posture management and prioritizing security measures can be a costly and challenging endeavor for these institutions—but there is a lot that school systems can do to protect themselves.  

Maintaining and scaling core cyberhygiene will be key to securing school systems. Building awareness of security risks and good practices at all levels—students, faculty, administrators, IT staff, campus staff, and more—can help create a safer environment.  

For IT and security professionals in the education sector, doing the basics and hardening the overall security posture is a good first step. From there, centralizing the technology stack can help facilitate better monitoring of logging and activity to gain a clearer picture into the overall security posture and any vulnerabilities. 

Oregon State University 

Oregon State University (OSU), an R1 research-focused university, places a high priority on safeguarding its research to maintain its reputation. In 2021, it experienced an extensive cybersecurity incident unlike anything before. The cyberattack revealed gaps in OSU’s security operations.

“The types of threats that we’re seeing, the types of events that are occurring in higher education, are much more aggressive by cyber adversaries.”

—David McMorries, Chief Information Security Officer at Oregon State University

In response to this incident, OSU created its Security Operations Center (SOC), which has become the centerpiece of the university’s security effort. AI has also helped automate capabilities and helped its analysts, who are college students, learn how to quickly write code—such as threat hunting with more advanced hunting queries. 

Arizona Department of Education 

A focus on Zero Trust and closed systems is an area that the Arizona Department of Education (ADE) takes further than the state requirements. It blocks all traffic from outside the United States from its Microsoft 365 environment, Azure, and its local datacenter.

“I don’t allow anything exposed to the internet on my lower dev environments, and even with the production environments, we take extra care to make sure that we use a network security group to protect the app services.”

—Chris Henry, Infrastructure Manager at the Arizona Department of Education 

Follow these recommendations:  

• The best defense against QR code attacks is to be aware and pay attention. Pause, inspect the code’s URL before opening it, and don’t open QR codes from unexpected sources, especially if the message uses urgent language or contains errors. 

• Consider implementing “protective domain name service,” a free tool that helps prevent ransomware and other cyberattacks by blocking computer systems from connecting to harmful websites. Prevent password spray attacks with a stringent password and deploy multifactor authentication.  

• Educate students and staff about their security hygiene, and encourage them to use multifactor authentication or passwordless protections. Studies have shown that an account is more than 99.9% less likely to be compromised when using multifactor authentication.   

• Microsoft has launched role-based trainings for leaders, educators, students, parents, and IT professionals aligned to recommendations of the United States Cybersecurity and Infrastructure Security Agency.    

Corey Lee has always had an interest in solving puzzles and crimes. He started his college career at Penn State University in criminal justice, but soon realized his passion for digital forensics after taking a course about investigating a desktop computer break-in.  

After completing his degree in security and risk analysis, Corey came to Microsoft focused on gaining cross-industry experience. He’s worked on securing everything from federal, state, and local agencies to commercial enterprises, but today he focuses on the education sector.  

After spending time working across industries, Corey sees education through a different lens—the significantly unique industry of industries. The dynamics at play inside the education sector include academic institutions, financial services, critical infrastructure like hospitals and transportation, and partnerships with government agencies. According to Corey, working in such a broad field allows him to leverage skillsets from multiple industries to address specific problems across the landscape. 

The fact that education could also be called underserved from a cybersecurity standpoint is another compelling challenge, and part of Corey’s personal mission. The education industry needs cybersecurity experts to elevate the priority of protecting school systems. Corey works across the public and industry dialogue, skilling and readiness programs, incident response, and overall defense to protect not just the infrastructure of education, but students, parents, teachers, and staff. 

Today, Corey is focused reimagining student security operations centers, including how to inject AI into the equation and bring modern technology and training to the table. By growing the cybersecurity work force in education and giving them new tools, he’s working to elevate security in the sector in a way that’s commensurate with how critical the industry is for the future. 

Next steps with Microsoft Security

To learn more about Microsoft Security solutions, visit our website. Bookmark the Security blog to keep up with our expert coverage on security matters. Also, follow us on LinkedIn (Microsoft Security) and X (@MSFTSecurity) for the latest news and updates on cybersecurity.

¹Global Cyberattacks Continue to Rise with Africa and APAC Suffering Most, Check Point Blog. April 27, 2023.

²Cyber security breaches survey 2024: education institutions annex, The United Kingdom Department for Science, Innovation & Technology. April 9, 2024

³Scammers hide harmful links in QR codes to steal your information, Federal Trade Commission (Alvaro Puig), December 6, 2023.

Methodology: Snapshot and cover stat data represent telemetry from Microsoft Defender for Office 365 showing how a QR code phishing attack was disrupted by image detection technology and how Security Operations teams can respond to this threat. Platforms like Microsoft Entra provided anonymized data on threat activity, such as malicious email accounts, phishing emails, and attacker movement within networks. Additional insights are from the 78 trillion daily security signals processed by Microsoft each day, including the cloud, endpoints, the intelligent edge, and telemetry from Microsoft platforms and services including Microsoft Defender. Microsoft categorizes threat actors into five key groups: influence operations; groups in development; and nation-state, financially motivated, and private sector offensive actors. The new threat actors naming taxonomy aligns with the theme of weather.  

© 2024 Microsoft Corporation. All rights reserved. Cyber Signals is for informational purposes only. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS DOCUMENT. This document is provided “as is.” Information and views expressed in this document, including URL and other Internet website references, may change without notice. You bear the risk of using it. This document does not provide you with any legal rights to any intellectual property in any Microsoft product. 

The post ​​Cyber Signals Issue 8 | Education under siege: How cybercriminals target our schools​​ appeared first on Microsoft Security Blog.

Legitimate hosting services, such as SharePoint, OneDrive, and Dropbox, are widely used by organizations for storing, sharing, and collaborating on files. However, the widespread use of such services also makes them attractive targets for threat actors, who exploit the trust and familiarity associated with these services to deliver malicious files and links, often avoiding detection by traditional security measures.

Importantly, Microsoft takes action against malicious users violating the Microsoft Services Agreement in how they use apps like SharePoint and OneDrive. To help protect enterprise accounts from compromise, by default both Microsoft 365 and Office 365 support multi-factor authentication (MFA) and passwordless sign-in. Consumers can also go passwordless with their Microsoft account. Because security is a team sport, Microsoft also works with third parties like Dropbox to share threat intelligence and protect mutual customers and the wider community.

In this blog, we discuss the typical attack chain used in campaigns misusing file hosting services and detail the recently observed tactics, techniques, and procedures (TTPs), including the increasing use of certain defense evasion tactics. To help defenders protect their identities and data, we also share mitigation guidance to help reduce the impact of this threat, and detection details and hunting queries to locate potential misuse of file hosting services and related threat actor activities. By understanding these evolving threats and implementing the recommended mitigations, organizations can better protect themselves against these sophisticated campaigns and safeguard digital assets.

Attack overview

Phishing campaigns exploiting legitimate file hosting services have been trending throughout the last few years, especially due to the relative ease of the technique. The files are delivered through different approaches, including email and email attachments like PDFs, OneNote, and Word files, with the intent of compromising identities or devices. These campaigns are different from traditional phishing attacks because of the sophisticated defense evasion techniques used.

Since mid-April 2024, we observed threat actors increasingly use these tactics aimed at circumventing defense mechanisms:

• Files with restricted access: The files sent through the phishing emails are configured to be accessible solely to the designated recipient. This requires the recipient to be signed in to the file-sharing service—be it Dropbox, OneDrive, or SharePoint—or to re-authenticate by entering their email address along with a one-time password (OTP) received through a notification service.
• Files with view-only restrictions: To bypass analysis by email detonation systems, the files shared in these phishing attacks are set to ‘view-only’ mode, disabling the ability to download and consequently, the detection of embedded URLs within the file.

An example attack chain is provided below, depicting the updated defense evasion techniques being used across stages 4, 5, and 6:

Initial access

The attack typically begins with the compromise of a user within a trusted vendor. After compromising the trusted vendor, the threat actor hosts a file on the vendor’s file hosting service, which is then shared with a target organization. This misuse of legitimate file hosting services is particularly effective because recipients are more likely to trust emails from known vendors, allowing threat actors to bypass security measures and compromise identities. Often, users from trusted vendors are added to allow lists through policies set by the organization on Exchange Online products, enabling phishing emails to be successfully delivered.

While file names observed in these campaigns also included the recipients, the hosted files typically follow these patterns:

• Familiar topics based on existing conversations
  • For example, if the two organizations have prior interactions related to an audit, the shared files could be named “Audit Report 2024”.
• Familiar topics based on current context
  • If the attack has not originated from a trusted vendor, the threat actor often impersonates administrators or help desk or IT support personnel in the sender display name and uses a file name such as “IT Filing Support 2024”, “Forms related to Tax submission”, or “Troubleshooting guidelines”.
• Topics based on urgency
  • Another common technique observed by the threat actors creating these files is that they create a sense of urgency with the file names like “Urgent:Attention Required” and “Compromised Password Reset”.

Defense evasion techniques

Once the threat actor shares the files on the file hosting service with the intended users, the file hosting service sends the target user an automated email notification with a link to access the file securely. This email is not a phishing email but a notification for the user about the sharing action. In scenarios involving SharePoint or OneDrive, the file is shared from the user’s context, with the compromised user’s email address as the sender. However, in the Dropbox scenario, the file is shared from no-reply@dropbox[.]com. The files are shared through automated notification emails with the subject: “<User> shared <document> with you”. To evade detections, the threat actor deploys the following additional techniques:

• Only the intended recipient can access the file
  • The intended recipient needs to re-authenticate before accessing the file
  • The file is accessible only for a limited time window
• The PDF shared in the file cannot be downloaded

These techniques make detonation and analysis of the sample with the malicious link almost impossible since they are restricted.

Identity compromise

When the targeted user accesses the shared file, the user is prompted to verify their identity by providing their email address:

Next, an OTP is sent from no-reply@notify.microsoft[.]com. Once the OTP is submitted, the user is successfully authorized and can view a document, often masquerading as a preview, with a malicious link, which is another lure to make the targeted user click the “View my message” access link.

This link redirects the user to an adversary-in-the-middle (AiTM) phishing page, where the user is prompted to provide the password and complete multifactor authentication (MFA). The compromised token can then be leveraged by the threat actor to perform the second stage BEC attack and continue the campaign.

Recommended actions

Microsoft recommends the following mitigations to reduce the impact of this threat:

• Enable Conditional Access policies in Microsoft Entra, especially risk-based access policies. Conditional access policies evaluate sign-in requests using additional identity-driven signals like user or group membership, IP address location information, and device status, among others, are enforced for suspicious sign-ins. Organizations can protect themselves from attacks that leverage stolen credentials by enabling policies such as compliant devices, Azure trusted IP address requirements, or risk-based policies with proper access control. If you are still evaluating Conditional Access, use security defaults as an initial baseline set of policies to improve identity security posture.
• Implement continuous access evaluation.
• Implement Microsoft Entra passwordless sign-in with FIDO2 security keys.
• Turn on network protection in Microsoft Defender for Endpoint to block connections to malicious domains and IP addresses.
• Implement Microsoft Defender for Endpoint – Mobile Threat Defense on mobile devices used to access enterprise assets.
• Leverage Microsoft Edge to automatically identify and block malicious websites, including those used in this phishing campaign, and Microsoft Defender for Office 365 to detect and block malicious emails, links, and files. Monitor suspicious or anomalous activities in Microsoft Entra ID Protection. Investigate sign-in attempts with suspicious characteristics (such as the location, ISP, user agent, and use of anonymizer services). Educate users about the risks of secure file sharing and emails from trusted vendors.

Appendix

Microsoft Defender XDR detections

Microsoft Defender XDR raises the following alerts by combining Microsoft Defender for Office 365 URL click and Microsoft Entra ID Protection risky sign-ins signal.

• Risky sign-in after clicking a possible AiTM phishing URL
• User compromised through session cookie hijack
• User compromised in a known AiTM phishing kit

Hunting queries

Microsoft Defender XDR 

The file sharing events related to the activity in this blog post can be audited through the CloudAppEvents telemetry. Microsoft Defender XDR customers can run the following query to find related activity in their networks: 

Automated email notifications and suspicious sign-in activity

By correlating the email from the Microsoft notification service or Dropbox automated notification service with a suspicious sign-in activity, we can identify compromises, especially from securely shared SharePoint or Dropbox files.

let usersWithSuspiciousEmails = EmailEvents
    | where SenderFromAddress in ("no-reply@notify.microsoft.com", "no-reply@dropbox.com") or InternetMessageId startswith "<OneTimePasscode"
    | where isnotempty(RecipientObjectId)
    | distinct RecipientObjectId;
AADSignInEventsBeta
| where AccountObjectId in (usersWithSuspiciousEmails)
| where RiskLevelDuringSignIn == 100

Files share contents and suspicious sign-in activity

In the majority of the campaigns, the file name involves a sense of urgency or content related to finance or credential updates. By correlating the file share emails with suspicious sign-ins, compromises can be detected. (For example: Alex shared “Password Reset Mandatory.pdf” with you). Since these are observed as campaigns, validating that the same file has been shared with multiple users in the organization can support the detection.

let usersWithSuspiciousEmails = EmailEvents
    | where Subject has_all ("shared", "with you")
    | where Subject has_any ("payment", "invoice", "urgent", "mandatory", "Payoff", "Wire", "Confirmation", "password")
    | where isnotempty(RecipientObjectId)
    | summarize RecipientCount = dcount(RecipientObjectId), RecipientList = make_set(RecipientObjectId) by Subject
    | where RecipientCount >= 10
    | mv-expand RecipientList to typeof(string)
    | distinct RecipientList;
AADSignInEventsBeta
| where AccountObjectId in (usersWithSuspiciousEmails)
| where RiskLevelDuringSignIn == 100

BEC: File sharing tactics based on the file hosting service used

To initiate the file sharing activity, these campaigns commonly use certain action types depending on the file hosting service being leveraged. Below are the action types from the audit logs recorded for the file sharing events. These action types can be used to hunt for activities related to these campaigns by replacing the action type for its respective application in the queries below this table.

OneDrive or SharePoint: The following query highlights that a specific file has been shared by a user with multiple participants. Correlating this activity with suspicious sign-in attempts preceding this can help identify lateral movements and BEC attacks.

let securelinkCreated = CloudAppEvents
    | where ActionType == "SecureLinkCreated"
    | project FileCreatedTime = Timestamp, AccountObjectId, ObjectName;
let filesCreated = securelinkCreated
    | where isnotempty(ObjectName)
    | distinct tostring(ObjectName);
CloudAppEvents
| where ActionType == "AddedToSecureLink"
| where Application in ("Microsoft SharePoint Online", "Microsoft OneDrive for Business")
| extend FileShared = tostring(RawEventData.ObjectId)
| where FileShared in (filesCreated)
| extend UserSharedWith = tostring(RawEventData.TargetUserOrGroupName)
| extend TypeofUserSharedWith = RawEventData.TargetUserOrGroupType
| where TypeofUserSharedWith == "Guest"
| where isnotempty(FileShared) and isnotempty(UserSharedWith)
| join kind=inner securelinkCreated on $left.FileShared==$right.ObjectName
// Secure file created recently (in the last 1day)
| where (Timestamp - FileCreatedTime) between (1d .. 0h)
| summarize NumofUsersSharedWith = dcount(UserSharedWith) by FileShared
| where NumofUsersSharedWith >= 20

Dropbox: The following query highlights that a file hosted on Dropbox has been shared with multiple participants.

CloudAppEvents
| where ActionType in ("Added users and/or groups to shared file/folder", "Invited user to Dropbox and added them to shared file/folder")
| where Application == "Dropbox"
| where ObjectType == "File"
| extend FileShared = tostring(ObjectName)
| where isnotempty(FileShared)
| mv-expand ActivityObjects
| where ActivityObjects.Type == "Account" and ActivityObjects.Role == "To"
| extend SharedBy = AccountId
| extend UserSharedWith = tostring(ActivityObjects.Name)
| summarize dcount(UserSharedWith) by FileShared, AccountObjectId
| where dcount_UserSharedWith >= 20

Microsoft Sentinel

Microsoft Sentinel customers can use the resources below to find related activities similar to those described in this post:

The following query identifies files with specific keywords that attackers might use in this campaign that have been shared through OneDrive or SharePoint using a Secure Link and accessed by over 10 unique users. It captures crucial details like target users, client IP addresses, timestamps, and file URLs to aid in detecting potential attacks:

let OperationName = dynamic(['SecureLinkCreated', 'AddedToSecureLink']);
OfficeActivity
| where Operation in (OperationName)
| where OfficeWorkload in ('OneDrive', 'SharePoint')
| where SourceFileName has_any ("payment", "invoice", "urgent", "mandatory", "Payoff", "Wire", "Confirmation", "password", "paycheck", "bank statement", "bank details", "closing", "funds", "bank account", "account details", "remittance", "deposit", "Reset")
| summarize CountOfShares = dcount(TargetUserOrGroupName), 
            make_list(TargetUserOrGroupName), 
            make_list(ClientIP), 
            make_list(TimeGenerated), 
            make_list(SourceRelativeUrl) by SourceFileName, OfficeWorkload
| where CountOfShares > 10

Considering that the attacker compromises users through AiTM,  possible AiTM phishing attempts can be detected through the below rule:

• Possible AiTM Phishing Attempt

In addition, customers can also use the following identity-focused queries to detect and investigate anomalous sign-in events that may be indicative of a compromised user identity being accessed by a threat actor:

• Signins From VPS Providers
• Signins from Nord VPN Providers
• Successful Signin From Non-Compliant Device

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, and on X (formerly Twitter) at https://twitter.com/MsftSecIntel.

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 File hosting services misused for identity phishing appeared first on Microsoft Security Blog.

Storm-0501 has been active as early as 2021, initially observed deploying the Sabbath(54bb47h) ransomware in attacks targeting US school districts, publicly leaking data for extortion, and even directly messaging school staff and parents. Since then, most of the threat actor’s attacks have been opportunistic, as the group began operating as a ransomware-as-a-service (RaaS) affiliate deploying multiple ransomware payloads developed and maintained by other threat actors over the years, including Hive, BlackCat (ALPHV), Hunters International, LockBit, and most recently, Embargo ransomware. The threat actor was also recently observed targeting hospitals in the US.

Storm-0501 is the latest threat actor observed to exploit weak credentials and over-privileged accounts to move from organizations’ on-premises environment to cloud environments. They stole credentials and used them to gain control of the network, eventually creating persistent backdoor access to the cloud environment and deploying ransomware to the on-premises. Microsoft previously observed threat actors such as Octo Tempest and Manatee Tempest targeting both on-premises and cloud environments and exploiting the interfaces between the environments to achieve their goals.

As hybrid cloud environments become more prevalent, the challenge of securing resources across multiple platforms grows ever more critical for organizations. Microsoft is committed to helping customers understand these attacks and build effective defenses against them.

In this blog post, we will go over Storm-0501’s tactics, techniques, and procedures (TTPs), typical attack methods, and expansion to the cloud. We will also provide information on how Microsoft detects activities related to this kind of attack, as well as provide mitigation guidance to help defenders protect their environment.

Analysis of the recent Storm-0501 campaign

On-premises compromise

Initial access and reconnaissance

Storm-0501 previously achieved initial access through intrusions facilitated by access brokers like Storm-0249 and Storm-0900, leveraging possibly stolen compromised credentials to sign in to the target system, or exploiting various known remote code execution vulnerabilities in unpatched public-facing servers. In a recent campaign, Storm-0501 exploited known vulnerabilities in Zoho ManageEngine (CVE-2022-47966), Citrix NetScaler (CVE-2023-4966), and ColdFusion 2016 application (possibly CVE-2023-29300 or CVE-2023-38203). In cases observed by Microsoft, these initial access techniques, combined with insufficient operational security practices by the targets, provided the threat actor with administrative privileges on the target device.

After gaining initial access and code execution capabilities on the affected device in the network, the threat actor performed extensive discovery to find potential desirable targets such as high-value assets and general domain information like Domain Administrator users and domain forest trust. Common native Windows tools and commands, such as systeminfo.exe, net.exe, nltest.exe, tasklist.exe, were leveraged in this phase. The threat actor also utilized open-source tools like ossec-win32 and OSQuery to query additional endpoint information. Additionally, in some of the attacks, we observed the threat actor running an obfuscated version of ADRecon.ps1 called obfs.ps1 or recon.ps1 for Active Directory reconnaissance.

Following initial access and reconnaissance, the threat actor deployed several remote monitoring and management tools (RMMs), such as Level.io, AnyDesk, and NinjaOne to interact with the compromised device and maintain persistence.

Credential access and lateral movement

The threat actor took advantage of admin privileges on the local devices it compromised during initial access and attempted to gain access to more accounts within the network through several methods. The threat actor primarily utilized Impacket’s SecretsDump module, which extracts credentials over the network, and leveraged it across an extensive number of devices to obtain credentials. The threat actor used the compromised credentials to access more devices in the network and then leveraged Impacket again to collect additional credentials. The threat actor then repeated this process until they compromised a large set of credentials that potentially included multiple Domain Admin credentials.

In addition, the threat actor was observed attempting to gather secrets by reading sensitive files and in some cases gathering KeePass secrets from the compromised devices. The threat actor used EncryptedStore’s Find-KeePassConfig.ps1 PowerShell script to output the database location and keyfile/user master key information and launch the KeePass executable to gather the credentials. We assess with medium confidence that the threat actor also performed extensive brute force activity on a few occasions to gain additional credentials for specific accounts.

The threat actor was observed leveraging Cobalt Strike to move laterally across the network using the compromised credentials and using the tool’s command-and-control (C2) capabilities to directly communicate with the endpoints and send further commands. The common Cobalt Strike Beacon file types used in these campaigns were .dll files and .ocx files that were launched by rundll32.exe and regsvr32.exe respectively. Moreover, the “license_id” associated with this Cobalt Strike Beacon is “666”.  The “license_id” definition is commonly referred to as Watermark and is a nine-digit value that is unique per legitimate license provided by Cobalt Strike. In this case, the “license_id” was modified with 3-digit unique value in all the beacon configurations.

In cases we observed, the threat actor’s lateral movement across the campaign ended with a Domain Admin compromise and access to a Domain Controller that eventually enabled them to deploy ransomware across the devices in the network.

Data collection and exfiltration

The threat actor was observed exfiltrating sensitive data from compromised devices. To exfiltrate data, the threat actor used the open-source tool Rclone and renamed it to known Windows binary names or variations of them, such as svhost.exe or scvhost.exe as masquerading means. The threat actor employed the renamed Rclone binaries to transfer data to the cloud, using a dedicated configuration that synchronized files to public cloud storage services such as MegaSync across multiple threads. The following are command line examples used by the threat actor in demonstrating this behavior:

• Svhost.exe copy –filter-from [REDACTED] [REDACTED] config:[REDACTED] -q –ignore-existing –auto-confirm –multi-thread-streams 11 –transfers 11
• scvhost.exe –config C:\Windows\Debug\a.conf copy [REDACTED UNC PATH] [REDACTED]

Defense evasion

The threat actor attempted to evade detection by tampering with security products in some of the devices they got hands-on-keyboard access to. They employed an open-source tool, resorted to PowerShell cmdlets and existing binaries to evade detection, and in some cases, distributed Group Policy Object (GPO) policies to tamper with security products.

On-premises to cloud pivot

In their recent campaign, we noticed a shift in Storm-0501’s methods. The threat actor used the credentials, specifically Microsoft Entra ID (formerly Azure AD), that were stolen from earlier in the attack to move laterally from the on-premises to the cloud environment and establish persistent access to the target network through a backdoor.

Storm-0501 was observed using the following attack vectors and pivot points on the on-premises side to gain subsequent control in Microsoft Entra ID:

Microsoft Entra Connect Sync account compromise

Microsoft Entra Connect, previously known as Azure AD Connect, is an on-premises Microsoft application that plays a critical role in synchronizing passwords and sensitive data between Active Directory (AD) objects and Microsoft Entra ID objects. Microsoft Entra Connect synchronizes the on-premises identity and Microsoft Entra identity of a user account to allow the user to sign in to both realms with the same password. To deploy Microsoft Entra Connect, the application must be installed on an on-premises server or an Azure VM. To decrease the attack surface, Microsoft recommends that organizations deploy Microsoft Entra Connect on a domain-joined server and restrict administrative access to domain administrators or other tightly controlled security groups. Microsoft Incident Response also published recommendations on preventing cloud identity compromise.

Microsoft Entra Connect Sync is a component of Microsoft Entra Connect that synchronizes identity data between on-premises environments and Microsoft Entra ID. During the Microsoft Entra Connect installation process, at least two new accounts (more accounts are created if there are multiple forests) responsible for the synchronization are created, one in the on-premises AD realm and the other in the Microsoft Entra ID tenant. These service accounts are responsible for the synchronization process.

The on-premises account name is prefixed with “MSOL_” and has permissions to replicate directory changes, modify passwords, modify users, modify groups, and more (see full permissions here).

The cloud Microsoft Entra ID account is prefixed with “sync_<Entra Connect server name>_” and has the account display name set to “On-Premises Directory Synchronization Service Account”. This user account is assigned with the Directory Synchronization Accounts role (see detailed permissions of this role here). Microsoft recently implemented a change in Microsoft Entra ID that restricts permissions on the Directory Synchronization Accounts (DSA) role in Microsoft Entra Connect Sync and Microsoft Entra Cloud Sync and helps prevent abuse.

The on-premises and cloud service accounts conduct the syncing operation every few minutes, similar to Password Hash Synchronization (PHS), to uphold real time user experience. Both user accounts mentioned above are crucial for the Microsoft Entra Connect Sync service operations and their credentials are saved encrypted via DPAPI (Data Protection API) on the server’s disk or a remote SQL server.

We can assess with high confidence that in the recent Storm-0501 campaign, the threat actor specifically located Microsoft Entra Connect Sync servers and managed to extract the plain text credentials of the Microsoft Entra Connect cloud and on-premises sync accounts. We assess that the threat actor was able to achieve this because of the previous malicious activities described in this blog post, such as using Impacket to steal credentials and DPAPI encryption keys, and tampering with security products.

Following the compromise of the cloud Directory Synchronization Account, the threat actor can authenticate using the clear text credentials and get an access token to Microsoft Graph. The compromise of the Microsoft Entra Connect Sync account presents a high risk to the target, as it can allow the threat actor to set or change Microsoft Entra ID passwords of any hybrid account (on-premises account that is synced to Microsoft Entra ID).

Cloud session hijacking of on-premises user account

Another way to pivot from on-premises to Microsoft Entra ID is to gain control of an on-premises user account that has a respective user account in the cloud. In some of the Storm-0501 cases we investigated, at least one of the Domain Admin accounts that was compromised had a respective account in Microsoft Entra ID, with multifactor authentication (MFA) disabled, and assigned with a Global Administrator role. It is important to mention that the sync service is unavailable for administrative accounts in Microsoft Entra, hence the passwords and other data are not synced from the on-premises account to the Microsoft Entra account in this case. However, if the passwords for both accounts are the same, or obtainable by on-premises credential theft techniques (i.e. web browsers passwords store), then the pivot is possible.

If a compromised on-premises user account is not assigned with an administrative role in Microsoft Entra ID and is synced to the cloud and no security boundaries such as MFA or Conditional Access are set, then the threat actor could escalate to the cloud through the following:

1. If the password is known, then logging in to Microsoft Entra is possible from any device.
2. If the password is unknown, the threat actor can reset the on-premises user password, and after a few minutes the new password will be synced to the cloud.
3. If they hold credentials of a compromised Microsoft Entra Directory Synchronization Account, they can set the cloud password using AADInternals’ Set-AADIntUserPassword cmdlet.

If MFA for that user account is enabled, then authentication with the user will require the threat actor to tamper with the MFA or gain control of a device owned by the user and subsequently hijack its cloud session or extract its Microsoft Entra access tokens along with their MFA claims.

MFA is a security practice that requires users to provide two or more verification factors to gain access to a resource and is a recommended security practice for all users, especially for privileged administrators. A lack of MFA or Conditional Access policies limiting the sign-in options opens a wide door of possibilities for the attacker to pivot to the cloud environment, especially if the user has administrative privileges. To increase the security of admin accounts, Microsoft is rolling out additional tenant-level security measures to require MFA for all Azure users.

Impact

Cloud compromise leading to backdoor

Following a successful pivot from the on-premises environment to the cloud through the compromised Microsoft Entra Connect Sync user account or the cloud admin account compromised through cloud session hijacking, the threat actor was able to connect to Microsoft Entra (portal/MS Graph) from any device, using a privileged Microsoft Entra ID account, such as a Global Administrator, and was no longer limited to the compromised devices.

Once Global Administrator access is available for Storm-0501, we observed them creating a persistent backdoor access for later use by creating a new federated domain in the tenant. This backdoor enables an attacker to sign in as any user of the Microsoft Entra ID tenant in hand if the Microsoft Entra ID user property ImmutableId is known or set by the attackers. For users that are configured to be synced by the Microsoft Entra Connect service, the ImmutableId property is automatically populated, while for users that are not synced the default value is null. However, users with administrative privileges can add an ImmutableId value, regardless.

The threat actor used the open-source tool AADInternals, and its Microsoft Entra ID capabilities to create the backdoor. AADInternals is a PowerShell module designed for security researchers and penetration testers that provides various methods for interacting and testing Microsoft Entra ID and is commonly used by Storm-0501. To create the backdoor, the threat actor first needed to have a domain of their own that is registered to Microsoft Entra ID. The attacker’s next step is to determine whether the target domain is managed or federated. A federated domain in Microsoft Entra ID is a domain that is configured to use federation technologies, such as Active Directory Federation Services (AD FS), to authenticate users. If the target domain is managed, then the attackers need to convert it to a federated one and provide a root certificate to sign future tokens upon user authentication and authorization processes. If the target domain is already federated, then the attackers need to add the root certificate as “NextSigningCertificate”.

Once a backdoor domain is available for use, the threat actor creates a federation trust between the compromised tenant, and their own tenant. The threat actor uses the AADInternals commands that enable the creation of Security Assertion Markup Language (SAML or SAML2) tokens, which can be used to impersonate any user in the organization and bypass MFA to sign in to any application. Microsoft observed the actor using the SAML token sign in to Office 365.

On-premises compromise leading to ransomware

Once the threat actor achieved sufficient control over the network, successfully extracted sensitive files, and managed to move laterally to the cloud environment, the threat actor then deployed the Embargo ransomware across the organization. We observed that the threat actor did not always resort to ransomware distribution, and in some cases only maintained backdoor access to the network.

Embargo ransomware is a new strain developed in Rust, known to use advanced encryption methods. Operating under the RaaS model, the ransomware group behind Embargo allows affiliates like Storm-0501 to use its platform to launch attacks in exchange for a share of the ransom. Embargo affiliates employ double extortion tactics, where they first encrypt a victim’s files and threaten to leak stolen sensitive data unless a ransom is paid.

In the cases observed by Microsoft, the threat actor leveraged compromised Domain Admin accounts to distribute the Embargo ransomware via a scheduled task named “SysUpdate” that was registered via GPO on the devices in the network. The ransomware binaries names that were used were PostalScanImporter.exe and win.exe. Once the files on the target devices were encrypted, the encrypted files extension changed to .partial, .564ba1, and .embargo.

Mitigation and protection guidance

Microsoft recently implemented a change in Microsoft Entra ID that restricts permissions on the Directory Synchronization Accounts (DSA) role in Microsoft Entra Connect Sync and Microsoft Entra Cloud Sync as part of ongoing security hardening. This change helps prevent threat actors from abusing Directory Synchronization Accounts in attacks.

Customers may also refer to Microsoft’s human-operated ransomware overview for general hardening recommendations against ransomware attacks.

The other techniques used by threat actors and described in this blog can be mitigated by adopting the following security measures:

• Secure accounts with credential hygiene: practice the principle of least privilege and audit privileged account activity in your Microsoft Entra ID environments to slow and stop attackers.
• Enable Conditional Access policies – Conditional Access policies are evaluated and enforced every time the user attempts to sign in. Organizations can protect themselves from attacks that leverage stolen credentials by enabling policies such as device compliance or trusted IP address requirements.
  • Set a Conditional Access policy to limit the access of Microsoft Entra ID sync accounts from untrusted IP addresses to all cloud apps. The Microsoft Entra ID sync account is identified by having the role ‘Directory Synchronization Accounts’. Please refer to the Advanced Hunting section and check the relevant query to get those IP addresses.
• Implement Conditional Access authentication strength to require phishing-resistant authentication for employees and external users for critical apps.
• Follow Microsoft’s best practices for securing Active Directory Federation Services.  
• Refer to Azure Identity Management and access control security best practices for further steps and recommendations to manage, design, and secure your Azure AD environment can be found by referring.
• Ensure Microsoft Defender for Cloud Apps connectors are turned on for your organization to receive alerts on the Microsoft Entra ID sync account and all other users.
• Enable protection to prevent by-passing of cloud Microsoft Entra MFA when federated with Microsoft Entra ID.
• Set the validatingDomains property of federatedTokenValidationPolicy to “all” to block attempts to sign-in to any non-federated domain (like .onmicrosoft.com) with SAML tokens.
• Turn on Microsoft Entra ID protection to monitor identity-based risks and create risk-based conditional access policies to remediate risky sign-ins.
• Turn on tamper protection features to prevent attackers from stopping security services such as Microsoft Defender for Endpoint, which can help prevent hybrid cloud environment attacks such as Microsoft Entra Connect abuse.
• Refer to the recommendations in our attacker technique profile, including use of Windows Defender Application Control or AppLocker to create policies to block unapproved information technology (IT) management tools to protect against the abuse of legitimate remote management tools like AnyDesk or Level.io.
• Run endpoint detection and response (EDR) in block mode so that 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 detected post-breach.
• Turn on investigation and remediation in full automated mode to allow Defender for Endpoint to take immediate action on alerts to help remediate alerts, significantly reducing alert volume.

Detection details

Alerts with the following names can be in use when investigating the current campaign of Storm-0501.

Microsoft Defender XDR detections

Microsoft Defender Antivirus 

Microsoft Defender Antivirus detects the Cobalt Strike Beacon as the following:

• Behavior:Win32/CobaltStrike
• Backdoor:Win64/CobaltStrike
• HackTool:Win64/CobaltStrike

Additional Cobalt Strike components are detected as the following:

• TrojanDropper:PowerShell/Cobacis
• Trojan:Win64/TurtleLoader.CS
• Exploit:Win32/ShellCode.BN

Microsoft Defender Antivirus detects tools that enable Microsoft Entra ID enumeration as the following malware: 

• Backdoor:Win32/SuspAadInternalsUsage

Embargo Ransomware threat components are detected as the following:

• Ransom:Win32/Embargo

Microsoft Defender for Endpoint 

Alerts with the following titles in the security center can indicate threat activity related to Storm-0501 on your network:

• Ransomware-linked Storm-0501 threat actor detected

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 Adobe ColdFusion vulnerability exploitation
• Compromised account conducting hands-on-keyboard attack
• Ongoing hands-on-keyboard attacker activity detected (Cobalt Strike)
• Ongoing hands-on-keyboard attack via Impacket toolkit
• Suspicious Microsoft Defender Antivirus exclusion
• Attempt to turn off Microsoft Defender Antivirus protection
• Renaming of legitimate tools for possible data exfiltration
• BlackCat ransomware
• ‘Embargo’ ransomware was detected and was active
• Suspicious Group Policy action detected
• An active ‘Embargo’ ransomware was detected

The following alerts might indicate on-premises to cloud pivot through Microsoft Entra Connect:

• Entra Connect Sync credentials extraction attempt
• Suspicious cmdlets launch using AADInternals
• Potential Entra Connect Tampering
• Indication of local security authority secrets theft

Microsoft Defender for Identity

The following Microsoft Defender for Identity alerts can indicate activity related to this threat:

• Data exfiltration over SMB
• Suspected DCSync attack

Microsoft Defender for Cloud Apps

Microsoft Defender for Cloud Apps can detect abuse of permissions in Microsoft Entra ID and other cloud apps. Activities related to the Storm-0501 campaign described in this blog are detected as the following:

• Backdoor creation using AADInternals tool
• Compromised Microsoft Entra ID Cloud Sync account
• Suspicious sign-in to Microsoft Entra Connect Sync account
• Entra Connect Sync account suspicious activity following a suspicious login
• AADInternals tool used by a Microsoft Entra Sync account
• Suspicious login from AADInternals tool

Microsoft Defender Vulnerability Management

Microsoft Defender Vulnerability Management surfaces devices that may be affected by the following vulnerabilities used in this threat:

• CVE-2022-47966

Threat intelligence reports 

Microsoft customers can use the following reports in Microsoft Defender Threat Intelligence 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: 

• Storm-0501

Advanced hunting 

Microsoft Defender XDR

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

Microsoft Entra Connect Sync account exploration

Explore sign-in activity from IdentityLogonEvents, look for uncommon behavior, such as sign-ins from newly seen IP addresses or sign-ins to new applications that are non-sync related.

IdentityLogonEvents
| where Timestamp > ago(30d)
| where AccountDisplayName contains "On-Premises Directory Synchronization Service Account"
| extend ApplicationName = tostring(RawEventData.ApplicationName)
| project-reorder Timestamp, AccountDisplayName, AccountObjectId, IPAddress, ActionType, ApplicationName, OSPlatform, DeviceType

Usually, the activity of the sync account is repetitive, coming from the same IP address to the same application, any deviation from the natural flow is worth investigating. Cloud applications that normally accessed by the Microsoft Entra ID sync account are “Microsoft Azure Active Directory Connect”, “Windows Azure Active Directory”, “Microsoft Online Syndication Partner Portal”

Explore the cloud activity (a.k.a ActionType) of the sync account, same as above, this account by nature performs a certain set of actions including ‘update User.’, ‘update Device.’ and so on. New and uncommon activity from this user might indicate an interactive use of the account, even though it could have been from someone inside the organization it could also be the threat actor.

CloudAppEvents
| where Timestamp > ago(30d)
| where AccountDisplayName has "On-Premises Directory Synchronization Service Account"
| extend Workload = RawEventData.Workload
| project-reorder Timestamp, IPAddress, AccountObjectId, ActionType, Application, Workload, DeviceType, OSPlatform, UserAgent, ISP

Pay close attention to action from different DeviceTypes or OSPlatforms, this account automated service is performed from one specific machine, so there shouldn’t be any variety in these fields.

Check which IP addresses Microsoft Entra Connect Sync account uses

This query reveals all IP addresses that the default Microsoft Entra Connect Sync account uses so those could be added as trusted IP addresses for the Entra ID sync account (make sure the account is not compromised before relying on this list)

IdentityLogonEvents
| where AccountDisplayName has "On-Premises Directory Synchronization Service Account"
| where ActionType == "LogonSuccess"
| distinct IPAddress
| union (CloudAppEvents
| where AccountDisplayName has "On-Premises Directory Synchronization Service Account"
| distinct IPAddress)
| distinct IPAddress

Federation and authentication domain changes

Explore the addition of a new authentication or federation domain, validate that the new domain is valid one and was purposefully added

CloudAppEvents
| where Timestamp > ago(30d)
| where ActionType in ("Set domain authentication.", "Set federation settings on domain.")

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.

Assess your environment for Manage Engine, Netscaler, and ColdFusion vulnerabilities.

DeviceTvmSoftwareVulnerabilities  
| where CveId in ("CVE-2022-47966","CVE-2023-4966","CVE-2023-29300","CVE-2023-38203")   
| project DeviceId,DeviceName,OSPlatform,OSVersion,SoftwareVendor,SoftwareName,SoftwareVersion,  
CveId,VulnerabilitySeverityLevel  
| join kind=inner ( DeviceTvmSoftwareVulnerabilitiesKB | project CveId, CvssScore,IsExploitAvailable,VulnerabilitySeverityLevel,PublishedDate,VulnerabilityDescription,AffectedSoftware ) on CveId  
| project DeviceId,DeviceName,OSPlatform,OSVersion,SoftwareVendor,SoftwareName,SoftwareVersion,  
CveId,VulnerabilitySeverityLevel,CvssScore,IsExploitAvailable,PublishedDate,VulnerabilityDescription,AffectedSoftware

Search for file IOC

let selectedTimestamp = datetime(2024-09-17T00:00:00.0000000Z);
let fileName = dynamic(["PostalScanImporter.exe","win.exe","name.dll","248.dll","cs240.dll","fel.ocx","theme.ocx","hana.ocx","obfs.ps1","recon.ps1"]); 
let FileSHA256 = dynamic(["efb2f6452d7b0a63f6f2f4d8db49433259249df598391dd79f64df1ee3880a8d","a9aeb861817f3e4e74134622cbe298909e28d0fcc1e72f179a32adc637293a40","caa21a8f13a0b77ff5808ad7725ff3af9b74ce5b67426c84538b8fa43820a031","53e2dec3e16a0ff000a8c8c279eeeca8b4437edb8ec8462bfbd9f64ded8072d9","827f7178802b2e92988d7cff349648f334bc86317b0b628f4bb9264285fccf5f","ee80f3e3ad43a283cbc83992e235e4c1b03ff3437c880be02ab1d15d92a8348a","de09ec092b11a1396613846f6b082e1e1ee16ea270c895ec6e4f553a13716304","d065623a7d943c6e5a20ca9667aa3c41e639e153600e26ca0af5d7c643384670","c08dd490860b54ae20fa9090274da9ffa1ba163f00d1e462e913cf8c68c11ac1"]); 
search in (AlertEvidence,BehaviorEntities,CommonSecurityLog,DeviceBaselineComplianceProfiles,DeviceEvents,DeviceFileEvents,DeviceImageLoadEvents, DeviceLogonEvents,DeviceNetworkEvents,DeviceProcessEvents,DeviceRegistryEvents,DeviceFileCertificateInfo,DynamicEventCollection,EmailAttachmentInfo,OfficeActivity,SecurityEvent,ThreatIntelligenceIndicator) TimeGenerated between ((selectedTimestamp - 1m) .. (selectedTimestamp + 90d)) // from September 17th runs the search for 90 days, change the selectedTimestamp accordingly. and  (FileName in (fileName) or OldFileName in (fileName)  or ProfileName in (fileName)  or InitiatingProcessFileName in (fileName)  or InitiatingProcessParentFileName in (fileName)  or InitiatingProcessVersionInfoInternalFileName in (fileName)  or InitiatingProcessVersionInfoOriginalFileName in (fileName)  or PreviousFileName in (fileName)  or ProcessVersionInfoInternalFileName in (fileName) or ProcessVersionInfoOriginalFileName in (fileName) or DestinationFileName in (fileName) or SourceFileName in (fileName)or ServiceFileName in (fileName) or SHA256 in (FileSHA256)  or InitiatingProcessSHA256 in (FileSHA256))

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 Defender XDR detections list above.

• Remote Management Monitoring Network Connections
• Level.io RMM File Signature
• AnyDesk RMM File Signature
• NinjaOne RMM File Signature
• Potential Impacket Execution
• Potential ransomware activity related to Cobalt Strike
• Cobalt DNS Beacon
• C2-NamedPipe
• Renamed Rclone Exfiltration
• Disable Or Modify Windows Defender
• Clearing of forensic evidence from event logs using wevtutil
• Suspicious Signin By AAD Connect Account

Indicators of compromise (IOCs)

The following list provides indicators of compromise (IOCs) observed during our investigation. We encourage our customers to investigate these indicators within their environments and implement detections and protections to identify any past related activity and prevent future attacks against their systems.

References

• The Rust Revolution: New Embargo Ransomware Steps In – Cyble
• Embargo Ransomware Group: The Interview (suspectfile.com)
• https://aadinternals.com/post/aadbackdoor/
• https://aadinternals.com/post/aad-deepdive/

Omri Refaeli, Tafat Gaspar, Vaibhav Deshmukh, Naya Hashem, Charles-Edouard Bettan

Microsoft Threat Intelligence Community

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, and on X (formerly Twitter) at https://twitter.com/MsftSecIntel.

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 Storm-0501: Ransomware attacks expanding to hybrid cloud environments appeared first on Microsoft Security Blog.

CVE-2024-7971 is a type confusion vulnerability in the V8 JavaScript and WebAssembly engine, impacting versions of Chromium prior to 128.0.6613.84. Exploiting the vulnerability could allow threat actors to gain RCE in the sandboxed Chromium renderer process. Google released a fix for the vulnerability on August 21, 2024, and users should ensure they are using the latest version of Chromium. We would like to thank the Chromium team for their collaboration in addressing this issue. CVE-2024-7971 is the third exploited V8 type confusion vulnerability that has been patched in V8 this year, after CVE-2024-4947 and CVE-2024-5274. As with any observed nation-state actor activity, Microsoft has directly notified targeted or compromised customers, providing them with important information to help secure their environments.

In this blog, we share details on the North Korean threat actor Citrine Sleet and the observed tactics, techniques, and procedures (TTPs) used to exploit CVE-2024-7971, deploy the FudModule rootkit, and compromise systems. We further provide recommended mitigations, detection details, hunting guidance, and indicators of compromise (IOCs) to help defenders identify, respond to, and improve defenses against these attacks.

Who is Citrine Sleet?

The threat actor that Microsoft tracks as Citrine Sleet is based in North Korea and primarily targets financial institutions, particularly organizations and individuals managing cryptocurrency, for financial gain. As part of its social engineering tactics, Citrine Sleet has conducted extensive reconnaissance of the cryptocurrency industry and individuals associated with it. The threat actor creates fake websites masquerading as legitimate cryptocurrency trading platforms and uses them to distribute fake job applications or lure targets into downloading a weaponized cryptocurrency wallet or trading application based on legitimate applications. Citrine Sleet most commonly infects targets with the unique trojan malware it developed, AppleJeus, which collects information necessary to seize control of the targets’ cryptocurrency assets. The FudModule rootkit described in this blog has now been tied to Citrine Sleet as shared tooling with Diamond Sleet.

The United States government has assessed that North Korean actors, like Citrine Sleet, will likely continue targeting vulnerabilities of cryptocurrency technology firms, gaming companies, and exchanges to generate and launder funds to support the North Korean regime. One of the organizations targeted by the CVE-2024-7971 exploitation was also previously targeted by Sapphire Sleet.

Citrine Sleet is tracked by other security companies as AppleJeus, Labyrinth Chollima, UNC4736, and Hidden Cobra, and has been attributed to Bureau 121 of North Korea’s Reconnaissance General Bureau.

Exploiting CVE-2024-7971

The observed zero-day exploit attack by Citrine Sleet used the typical stages seen in browser exploit chains. First, the targets were directed to the Citrine Sleet-controlled exploit domain voyagorclub[.]space. While we cannot confirm at this time how the targets were directed, social engineering is a common tactic used by Citrine Sleet. Once a target connected to the domain, the zero-day RCE exploit for CVE-2024-7971 was served.

After the RCE exploit achieved code execution in the sandboxed Chromium renderer process, shellcode containing a Windows sandbox escape exploit and the FudModule rootkit was downloaded, and then loaded into memory. The sandbox escape exploited CVE-2024-38106, a vulnerability in the Windows kernel that Microsoft fixed on August 13, 2024, before Microsoft discovered this North Korean threat actor activity. CVE-2024-38106 was reported to Microsoft Security Response Center (MSRC) as being exploited; however, our investigations so far have not suggested any link between the reported CVE-2024-38106 exploit activity and this Citrine Sleet exploit activity, beyond exploiting the same vulnerability. This may suggest a “bug collision,” where the same vulnerability is independently discovered by separate threat actors, or knowledge of the vulnerability was shared by one vulnerability researcher to multiple actors.

Once the sandbox escape exploit was successful, the main FudModule rootkit ran in memory. This rootkit employs direct kernel object manipulation (DKOM) techniques to disrupt kernel security mechanisms, executes exclusively from user mode, and performs kernel tampering through a kernel read/write primitive. We did not observe any additional malware activity on the target devices.

FudModule rootkit

FudModule is a sophisticated rootkit malware that specifically targets kernel access while evading detection. Threat actors have been observed using the FudModule data-only rootkit to establish admin-to-kernel access to Windows-based systems to allow read/write primitive functions and perform DKOM.

Diamond Sleet has been observed using FudModule since October 2021. The earliest variant of FudModule was reported publicly in September 2022 by ESET and AhnLAB researchers, when threat actors exploited known vulnerable drivers to establish admin-to-kernel access in the technique known as bring your own vulnerable driver (BYOVD). In February 2024, Avast researchers published analysis on an updated FudModule variant that is significantly more advanced and difficult to detect, since it exploits a zero-day vulnerability in appid.sys, an AppLocker driver that is installed by default into Windows (CVE-2024-21338).

Further research by Avast uncovered a full attack chain deploying the updated variant of FudModule known as “FudModule 2.0,” which includes malicious loaders and a late-stage remote access trojan (RAT). This attack chain revealed the previously unknown malware Kaolin RAT was responsible for loading the FudModule rootkit to targeted devices. Kaolin RAT established a secure, AES-encrypted connection with the command and control (C2) server and had capabilities to execute a robust list of commands, such as downloading and uploading files to the C2 server and creating or updating processes. The updated variant of FudModule exhibited an attack chain similar to that seen in Citrine Sleet’s zero-day exploit of CVE-2024-7971.

On August 13, Microsoft released a security update to address a zero-day vulnerability in the AFD.sys driver in Windows (CVE-2024-38193) identified by Gen Threat Labs. In early June, Gen Threat Labs identified Diamond Sleet exploiting this vulnerability in an attack employing the FudModule rootkit, which establishes full standard user-to-kernel access, advancing from the previously seen admin-to-kernel access. Gen Threat Labs released this information publicly on August 16.

Recommendations

The CVE-2024-7971 exploit chain relies on multiple components to compromise a target, and this attack chain fails if any of these components are blocked, including CVE-2024-38106. Microsoft released a security update on August 13, 2024, for the CVE-2024-38106 vulnerability exploited by Diamond Sleet, thus also blocking attempts to exploit the CVE-2024-7971 exploit chain on updated systems. Customers who have not implemented these fixes yet are urged to do so as soon as possible for their organization’s security.

Zero-day exploits necessitate not only keeping systems up to date, but also security solutions that provide unified visibility across the cyberattack chain to detect and block post-compromise attacker tools and malicious activity following exploitation. Microsoft recommends the following mitigations to reduce the impact of this threat.

Strengthen operating environment configuration

• Keep operating systems and applications up to date. Apply security patches as soon as possible. Ensure that Google Chrome web browser is updated at version 128.0.6613.84 or later, and Microsoft Edge web browser is updated at version 128.0.2739.42 or later to address the CVE-2024-7971 vulnerability.
• 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.

Strengthen Microsoft Defender for Endpoint configuration

• Ensure that tamper protection is turned on in Microsoft Dender for Endpoint.
• Enable network protection in Microsoft Defender for Endpoint.
• Run endpoint detection and response (EDR) in block mode so that Microsoft Defender for Endpoint can help 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 help 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 help resolve breaches, significantly reducing alert volume.

Strengthen Microsoft Defender Antivirus configuration

• Turn on cloud-delivered protection in Microsoft Defender Antivirus, or the equivalent for your antivirus product, to help cover rapidly evolving attacker tools and techniques. Cloud-based machine learning protections block majority of new and unknown variants.
• Turn on Microsoft Defender Antivirus scanning of downloaded files and attachments.
• Turn on real-time protection in Microsoft Defender Antivirus.

Detection details

Microsoft Defender for Endpoint

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

• Emerging threat activity group Citrine Sleet detected

Microsoft Defender Vulnerability Management

Microsoft Defender Vulnerability Management surfaces devices that may be affected by the following vulnerabilities used in this threat:

• CVE-2024-7971
• CVE-2024-38106

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 intelligence and protection information, and recommend actions to help prevent, mitigate, or respond to associated threats found in customer environments.

Microsoft Defender Threat Intelligence

• Actor profile: Citrine Sleet
• Actor profile: Diamond Sleet
• Tool profile: AppleJeus

Hunting queries

Microsoft Defender XDR

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

Citrine Sleet domain activity

Microsoft Defender XDR customers may query for devices that may have interacted with Citrine Sleet domains related to this activity. Note that Microsoft Defender for Endpoint customers may surface related events with the alert title “Emerging threat activity group Citrine Sleet detected”.

let domainList = dynamic(["weinsteinfrog.com", "voyagorclub.space"]);
union
(
    DnsEvents
    | where QueryType has_any(domainList) or Name has_any(domainList)
    | project TimeGenerated, Domain = QueryType, SourceTable = "DnsEvents"
),
(
    IdentityQueryEvents
    | where QueryTarget has_any(domainList)
    | project Timestamp, Domain = QueryTarget, SourceTable = "IdentityQueryEvents"
),
(
    DeviceNetworkEvents
    | where RemoteUrl has_any(domainList)
    | project Timestamp, Domain = RemoteUrl, SourceTable = "DeviceNetworkEvents"
),
(
    DeviceNetworkInfo
    | extend DnsAddresses = parse_json(DnsAddresses), ConnectedNetworks = parse_json(ConnectedNetworks)
    | mv-expand DnsAddresses, ConnectedNetworks
    | where DnsAddresses has_any(domainList) or ConnectedNetworks.Name has_any(domainList)
    | project Timestamp, Domain = coalesce(DnsAddresses, ConnectedNetworks.Name), SourceTable = "DeviceNetworkInfo"
),
(
    VMConnection
    | extend RemoteDnsQuestions = parse_json(RemoteDnsQuestions), RemoteDnsCanonicalNames = parse_json(RemoteDnsCanonicalNames)
    | mv-expand RemoteDnsQuestions, RemoteDnsCanonicalNames
    | where RemoteDnsQuestions has_any(domainList) or RemoteDnsCanonicalNames has_any(domainList)
    | project TimeGenerated, Domain = coalesce(RemoteDnsQuestions, RemoteDnsCanonicalNames), SourceTable = "VMConnection"
),
(
    W3CIISLog
    | where csHost has_any(domainList) or csReferer has_any(domainList)
    | project TimeGenerated, Domain = coalesce(csHost, csReferer), SourceTable = "W3CIISLog"
),
(
    EmailUrlInfo
    | where UrlDomain has_any(domainList)
    | project Timestamp, Domain = UrlDomain, SourceTable = "EmailUrlInfo"
),
(
    UrlClickEvents
    | where Url has_any(domainList)
    | project Timestamp, Domain = Url, SourceTable = "UrlClickEvents"
)
| order by TimeGenerated desc

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.

Search for domain IOCs

let domainList = dynamic(["weinsteinfrog.com", "voyagorclub.space"]); 
union 
( 
DnsEvents 
| where QueryType has_any(domainList) or Name has_any(domainList) 
| project TimeGenerated, Domain = QueryType, SourceTable = "DnsEvents" 
), 
( 
IdentityQueryEvents 
| where QueryTarget has_any(domainList) 
| project TimeGenerated, Domain = QueryTarget, SourceTable = "IdentityQueryEvents" 
), 
( 
DeviceNetworkEvents 
| where RemoteUrl has_any(domainList) 
| project TimeGenerated, Domain = RemoteUrl, SourceTable = "DeviceNetworkEvents" 
), 
( 
DeviceNetworkInfo 
| extend DnsAddresses = parse_json(DnsAddresses), ConnectedNetworks = parse_json(ConnectedNetworks) 
| mv-expand DnsAddresses, ConnectedNetworks 
| where DnsAddresses has_any(domainList) or ConnectedNetworks.Name has_any(domainList) 
| project TimeGenerated, Domain = coalesce(DnsAddresses, ConnectedNetworks.Name), SourceTable = "DeviceNetworkInfo" 
), 
( 
VMConnection 
| extend RemoteDnsQuestions = parse_json(RemoteDnsQuestions), RemoteDnsCanonicalNames = parse_json(RemoteDnsCanonicalNames) 
| mv-expand RemoteDnsQuestions, RemoteDnsCanonicalNames 
| where RemoteDnsQuestions has_any(domainList) or RemoteDnsCanonicalNames has_any(domainList) 
| project TimeGenerated, Domain = coalesce(RemoteDnsQuestions, RemoteDnsCanonicalNames), SourceTable = "VMConnection" 
), 
( 
W3CIISLog 
| where csHost has_any(domainList) or csReferer has_any(domainList) 
| project TimeGenerated, Domain = coalesce(csHost, csReferer), SourceTable = "W3CIISLog" 
), 
( 
EmailUrlInfo 
| where UrlDomain has_any(domainList) 
| project TimeGenerated, Domain = UrlDomain, SourceTable = "EmailUrlInfo" 
), 
( 
UrlClickEvents 
| where Url has_any(domainList) 
| project TimeGenerated, Domain = Url, SourceTable = "UrlClickEvents" 
),
(
CommonSecurityLog
| where DestinationDnsDomain has_any(domainList)
| project TimeGenerated, Domain = DestinationDnsDomain, SourceTable = "CommonSecurityLog" 
),
(
EmailEvents
| where SenderFromDomain has_any (domainList) or SenderMailFromDomain has_any (domainList)
| project TimeGenerated, SenderfromDomain = SenderFromDomain,SenderMailfromDomain = SenderMailFromDomain, SourceTable = "EmailEvents"
)
| order by TimeGenerated desc

Assess presence of vulnerabilities used by Citrine Sleet

DeviceTvmSoftwareVulnerabilities  
| where CveId has_any ("CVE-2024-7971","CVE-2024-38106","CVE-2024-38193","CVE-2024-21338")
| project DeviceId,DeviceName,OSPlatform,OSVersion,SoftwareVendor,SoftwareName,SoftwareVersion,  
CveId,VulnerabilitySeverityLevel  
| join kind=inner ( DeviceTvmSoftwareVulnerabilitiesKB | project CveId, CvssScore,IsExploitAvailable,VulnerabilitySeverityLevel,PublishedDate,VulnerabilityDescription,AffectedSoftware ) on CveId  
| project DeviceId,DeviceName,OSPlatform,OSVersion,SoftwareVendor,SoftwareName,SoftwareVersion,  
CveId,VulnerabilitySeverityLevel,CvssScore,IsExploitAvailable,PublishedDate,VulnerabilityDescription,AffectedSoftware

Indicators of compromise

During the attacks, Microsoft observed the following IOCs:

• voyagorclub[.]space
• weinsteinfrog[.]com

References

• https://nvd.nist.gov/vuln/detail/CVE-2024-7971
• https://chromereleases.googleblog.com/2024/08/stable-channel-update-for-desktop_21.html
• https://nvd.nist.gov/vuln/detail/CVE-2024-4947
• https://nvd.nist.gov/vuln/detail/CVE-2024-5274
• https://decoded.avast.io/janvojtesek/lazarus-and-the-fudmodule-rootkit-beyond-byovd-with-an-admin-to-kernel-zero-day/
• https://www.virusbulletin.com/uploads/pdf/conference/vb2022/papers/VB2022-Lazarus-and-BYOVD-evil-to-the-Windows-core.pdf
• https://asec.ahnlab.com/wp-content/uploads/2022/09/Analysis-Report-on-Lazarus-Groups-Rootkit-Attack-Using-BYOVD_Sep-22-2022.pdf
• https://decoded.avast.io/luiginocamastra/from-byovd-to-a-0-day-unveiling-advanced-exploits-in-cyber-recruiting-scams/
• https://www.gendigital.com/blog/news/innovation/protecting-windows-users
• https://www.google.com/chrome/update/
• https://chromereleases.googleblog.com/2024/08/stable-channel-update-for-desktop_21.html

Learn more

Read our blogs on threat actors, including Sleet actors. 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, and on X (formerly Twitter) at https://twitter.com/MsftSecIntel.

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 North Korean threat actor Citrine Sleet exploiting Chromium zero-day appeared first on Microsoft Security Blog.

Microsoft Incident Response

Strengthen your security with an end-to-end portfolio of proactive and reactive cybersecurity incident response services.

Learn more

Threat intelligence is often oversimplified to represent a feed of indicators of compromise (IOCs). The intersection between multiple types of threat intelligence, however, enables organizations and their threat hunters to have a holistic understanding of the cyberattackers and techniques that can and will target them. With this comprehensive cheat sheet of knowledge, threat hunters can not only increase efficiency when responding to a compromise, but proactively hunt their systems for anomalies and fine-tune protection and detection mechanisms. 

Figure 1. Three types of threat intelligence.

Figure 1 introduces three types of threat intelligence that will be outlined in this blog—strategic, operational, and tactical. It provides a visualization of organizational effort versus the value gained when utilizing threat intelligence in more than one way. Typically, security teams integrate IOC cyberthreat feeds at a tactical level, but incorporating threat intelligence operationally requires daily investment, especially when alert queues seem endless. Strategic threat intelligence may seem familiar to most organizations but can be challenging to apply effectively, as this requires concentrated effort at multiple levels to understand the organization’s position within the overall threat landscape. How can threat hunters leverage these types of threat intelligence effectively for the benefit of their organization? 

Strategic threat intelligence: Informed hunting driven by the overarching cyberthreat landscape 

Security teams should be industry aware—being cognizant of the types of digital threats and current trends affecting industry verticals allows any team to be better prepared for potential compromise. Strategic threat intelligence is fundamentally based on understanding threat actor motives, which gives organizations an understanding of which threat actors they should be most conscious of in relation to the industry vertical or their most valuable resources. For example, government entities are traditionally targeted by nation-state advanced persistent threats (APTs) to perform cyber espionage, whereas organizations in the healthcare industry are commonly targeted by cybercriminal actor groups for ransomware operations and financial extortion due to the sensitivity of the data they possess. Understanding where the organization fits into this strategic picture determines the investment where its resources (people and time) may be constrained. Furthermore, it’s a key step toward developing an effective threat-informed defense strategy prioritizing the cyberattacks that target the organization.  

Operational threat intelligence: Informed hunting to proactively understand the environment and its data 

Having broad visibility into an organization’s attack surface is imperative when applying threat intelligence at an operational level. The crucial components spanning the perimeter of the on-premises network and extended entities such as cloud, software-as-a-service, and overall supply chain should be well understood: 

• Where are the tier 0 systems in the organization? 
• What intermediary lateral movement pathways exist to tier 0 systems? 
• What security controls across the environment are (or aren’t) in place? 
• What telemetry is produced by all systems in the environment?  

Security teams should proactively analyze the data that comes from these entities to develop a baseline of normal operations. Along with this baseline, threat hunters should comprehend and exercise organizational processes. In the event of an identified anomaly, how is that behavior deconflicted? What teams within the organization need to be consulted? What is the process for ensuring false positives can be reported and circulated efficiently and effectively? Considering the secondary questions and tertiary actions of response steps greatly benefits threat hunting timeliness, staving off confusion during a rapidly evolving incident.

Tactical threat intelligence: Informed hunting to reactively respond to a live cyberthreat 

Tactical threat intelligence is often an organization’s main integration to enhance a threat hunt, particularly in response to an active cyberattack scenario. Known-bad entities and atomic indicators such as IP addresses, domains, and file hashes are used to identify anomalies aligning to attacker techniques against targeted systems quickly. Additionally, if the cyberattack is already attributed to a threat actor, or the attack aligns to a particular motive, security teams can use these patterns of behavior to prioritize their hunting scope to their known tactics, techniques, and procedures. Novel indicators or associated research from the analysis should be shared with other vetted threat hunters within the organization and are a particularly valuable contribution to the wider threat intelligence community to further enrich detections for all organizations.  

Putting it together: Threat intelligence and iterative threat hunting 

Armed with this breakdown, threat hunters can now turn their attention to using varied threat intelligence to execute threat hunts and track down threat actors. The threat hunting iterative workflow shown in Figure 2 is something security teams will likely be familiar with; but are threat intelligence artifacts effectively being applied to create a holistic threat-informed defense strategy? 

Figure 2. Feeding threat intelligence artifacts into an iterative threat hunting workflow.

When preparing a hunt, threat hunters should seek to apply strategic threat intelligence to prioritize the cyberthreats that target the organization. This directly leads into the hypothesis phase. Threat hunters include the gathered strategic artifacts in a hunt hypothesis based on the trends or threat actors impacting other organizations in the same vertical. This casts a wide net to identify anomalies and behaviors common to the industry. They are not limiting the hunt based on any one IOC, rather using the collective intelligence learned from similar intrusions to detect or prevent the attack scenario. For every investigation, whether it be proactive or reactive, Microsoft Incident Response threat hunters consider other incidents impacting victim organizations in the same industry as a guiding force to efficiently identify focus areas of analysis, leveraging research from Microsoft Threat Intelligence that outlines any applicable threat actor attribution. 

Daily workflows should be enhanced with operational threat intelligence artifacts to determine an environmental baseline. Proactive hunt hypotheses should seek to test the understanding and actively seek to identify gaps in various aspects of the baseline, identifying any behavioral anomalies straying from “normal operations” and developing high-fidelity, real-world detections based on the true attempts at intrusion to their environments. Existing detections should be continuously reviewed and refined, hunting threads should include interrogation of both successful and failed access attempts, and data integrity should be verified. Security teams should question if: 

• Centralized data is both complete and accurate—identifying if there are any gaps in the data and why. 
• The schema is consistent between all data sources (for example, timestamp accuracy). 
• The correct fields are flowing through from their distributed systems’ sources.  

When security teams embody being the experts of their environment, they become more adept at identifying when a proactive threat hunt shifts into reactive response to active threat. This is invaluable when improving the speed of returning to normal operations and engaging additional support such as Microsoft Incident Response, who can enhance the hunt with threat intelligence from previous global incidents, working with the customer to deconflict abnormalities quickly for swift takeback and eviction of threat actors. 

When incident response teams like Microsoft Incident Response are engaged during a reactive incident, the objective of threat hunting is to conduct analysis of live, historical, and contextual data on targeted and compromised systems and provide a detailed story of not only the attack chain, but the threat actor(s) conducting that attack. Enriching a threat hunt with tactical threat intelligence artifacts in the form of IOCs concentrates investigation scope and allows for rapid identification of threat actor activity. As the hunt progresses, relational entities to that indicator are uncovered, such as the identities involved in activity execution and lateral movement paths to different systems. Attention shifts from atomic indicators such as IP addresses and malicious domains, to artifacts left directly on compromised systems, such as commands that were run or persistent backdoors that were installed. This builds an end-to-end timeline of malicious activity and related indicators for organizations to stay informed, implement target security controls, and prevent the same, or similar, incidents in the future.  

Adhering to the collaborative cycle of threat intelligence, Microsoft Incident Response contributes front-line research to enhance and further develop detections for customers worldwide. Entities are aligned with industry frameworks such as the Diamond Model, to build threat actor profiles detailing the relationship between adversaries’ infrastructure, capabilities and victims. Microsoft Threat Intelligence is available in Microsoft Defender XDR for the community and fellow security teams to consume, validate, and refine into proactive detections for the organization. 

How Microsoft Incident Response can support proactive threat protection

Microsoft Incident Response has cultivated and relies upon implementing the cycle between incident response and threat intelligence to protect our customers, leveraging insights from 78 trillion signals per day. Organizations can proactively position themselves to be well-informed by the threats targeting their organization by implementing threat intelligence in a holistic way, before an incident begins.  

Embracing a collaborative culture amongst the threat intelligence community to not only consume entities, but to further contribute, refine, and enhance existing research, results in improved detections, controls, and automation, allowing all security professionals to get behind the same goal—track down and protect themselves from threat actors and their malicious intent.  

You can read more blogs from Microsoft Incident Response. For more security research from the Microsoft Threat Intelligence community, check out the Microsoft Threat Intelligence Blog.

Learn more

Learn more about Microsoft Incident Response.

To get notified about new Microsoft Threat Intelligence publications and to join discussions on social media, follow us on X (@MsftSecIntel).

To learn more about Microsoft Security solutions, visit our website. Bookmark the Security blog to keep up with our expert coverage on security matters. Also, follow us on LinkedIn (Microsoft Security) and X (@MSFTSecurity) for the latest news and updates on cybersecurity.

¹The art and science behind Microsoft threat hunting: Part 1, Microsoft Incident Response Team. September 9, 2022.

²The art and science behind Microsoft threat hunting: Part 2, Microsoft Incident Response Team. September 21, 2022.

The post The art and science behind Microsoft threat hunting: Part 3 appeared first on Microsoft Security Blog.

Peach Sandstorm also continued conducting password spray attacks against the educational sector for infrastructure procurement and against the satellite, government, and defense sectors as primary targets for intelligence collection. In addition, Microsoft observed intelligence gathering and possible social engineering targeting organizations within the higher education, satellite, and defense sectors via the professional networking platform LinkedIn.

Microsoft assesses that Peach Sandstorm operates on behalf of the Iranian Islamic Revolutionary Guard Corps (IRGC) based on the group’s victimology and operational focus. Microsoft further assesses that Peach Sandstorm’s operations are designed to facilitate intelligence collection in support of Iranian state interests.

Microsoft tracks Peach Sandstorm campaigns and directly notifies customers who we observe have been targeted or compromised, providing them with the necessary information to help secure their environment. As part of our continuous monitoring, analysis, and reporting on the threat landscape, we are sharing our research on Peach Sandstorm’s use of Tickler to raise awareness of this threat actor’s evolving tradecraft and to educate organizations on how to harden their attack surfaces against this and similar activity. Microsoft published information on unrelated election interference linked to Iran in the most recent Microsoft Threat Analysis Center (MTAC) report.

Evolution of Peach Sandstorm tradecraft

In past campaigns, Peach Sandstorm has been observed to use password spray attacks to gain access to targets of interest with a high level of success. The threat actor has also conducted intelligence gathering via LinkedIn, researching organizations and individuals employed in the higher education, satellite, and defense sectors.

During the group’s latest operations, Microsoft observed new tactics, techniques, and procedures (TTPs) following initial access via password spray attacks or social engineering. Between April and July 2024, Peach Sandstorm deployed a new custom multi-stage backdoor, Tickler, and leveraged Azure infrastructure hosted in fraudulent, attacker-controlled Azure subscriptions for command-and-control (C2). Microsoft continuously monitors Azure, along with all Microsoft products and services, to ensure compliance with our terms of service. Microsoft has notified affected organizations and disrupted the fraudulent Azure infrastructure and accounts associated with this activity.

Intelligence gathering on LinkedIn

Going back to at least November 2021 and continuing through mid-2024, Microsoft observed Peach Sandstorm using multiple LinkedIn profiles masquerading as students, developers, and talent acquisition managers based in the US and Western Europe. Peach Sandstorm primarily used them to conduct intelligence gathering and possible social engineering against the higher education, satellite sectors, and related industries. The identified LinkedIn accounts were subsequently taken down. Information on LinkedIn’s policies and actions against inauthentic behavior on its platform is available here.

Password spray attacks as a common attack vector

Since at least February 2023, Microsoft has observed Peach Sandstorm carrying out password spray activity against thousands of organizations. In password spray attacks, threat actors attempt to authenticate to many different accounts using a single password or a list of commonly used passwords. In contrast to brute force attacks, which target a single account using many passwords, password spray attacks help adversaries maximize their chances for success and minimize the likelihood of automatic account lockouts.

Microsoft has observed that once Peach Sandstorm has verified a target account’s credentials using the password spray technique, the threat actor performed subsequent sign-ins to the compromised accounts from commercial VPN infrastructure.

In April and May 2024, Microsoft observed Peach Sandstorm conducting password spray attacks targeting organizations in the defense, space, education, and government sectors in the US and Australia. In particular, Peach Sandstorm continued to use the “go-http-client” user agent that they are known to leverage in password spray campaigns. While the password spray activity appeared consistently across sectors, Microsoft observed Peach Sandstorm exclusively leveraging compromised user accounts in the education sector to procure operational infrastructure. In these cases, the threat actor accessed existing Azure subscriptions or created one using the compromised account to host their infrastructure. The attacker-controlled Azure infrastructure then served as C2 or operational hops for Peach Sandstorm operations targeting the government, defense, and space sectors. Recent updates to security defaults in Azure, such as multi-factor authentication help ensure that Azure accounts are more resistant to account compromise techniques such as those used by Peach Sandstorm.

Tickler malware

Microsoft Threat Intelligence identified two samples of the Tickler malware, a custom multi-stage backdoor, that Peach Sandstorm deployed in compromised environments as recently as July 2024. The first sample was contained in an archive file named Network Security.zip alongside benign PDF files used as decoy documents. The archive file contained:

• YAHSAT NETWORK_INFRASTRUCTURE_SECURITY_GUIDE_20240421.pdf.exe – theTickler malware
• Yahsat Policy Guide- April 2024.pdf – a benign PDF
• YAHSAT NETWORK_INFRASTRUCTURE_SECURITY_GUIDE_20240421.pdf – a second benign PDF

YAHSAT NETWORK_INFRASTRUCTURE_SECURITY_GUIDE_20240421.pdf.exe is a 64-bit C/C++ based native PE file. The sample begins with a Process Environment Block (PEB) traversal to locate the in-memory address of file kernell32.dll.

Upon successful PEB traversal yielding the address of kernell32.dll in memory, the sample decrypts a string to LoadLibraryA and resolves its address, decrypts the string “kernel32.dll”, and loads it again using LoadLibraryA. The sample then launches the benign PDF file YAHSAT NETWORK_INFRASTRUCTURE_SECURITY_GUIDE_20240421.pdf as a decoy document.

The sample collects the network information from the host and sends it to the C2 URI via HTTP POST request, likely as a means for the threat actor to orient themselves on the compromised network. The below network information is an example generated in a lab environment:

We subsequently observed Peach Sandstorm iterating and improving on this initial sample. The second Tickler sample, sold.dll, is a Trojan dropper functionally identical to the previously identified sample. The malware downloads additional payloads from the C2 server, including a backdoor, a batch script to set persistence for this backdoor, and the following legitimate files:

• msvcp140.dll (SHA-256: dad53a78662707d182cdb230e999ef6effc0b259def31c196c51cc3e8c42a9b8)
• LoggingPlatform.dll (SHA-256: 56ac00856b19b41bc388ecf749eb4651369e7ced0529e9bf422284070de457b6)
• vcruntime140.dll (SHA-256: 22017c9b022e6f2560fee7d544a83ea9e3d85abee367f2f20b3b0448691fe2d4)
• Microsoft.SharePoint.NativeMessaging.exe (SHA-256: e984d9085ae1b1b0849199d883d05efbccc92242b1546aeca8afd4b1868c54f5)

The files msvcp140.dll, LoggingPlatform.dll, vcruntime140.dll, and Microsoft.SharePoint.NativeMessaging.exe are legitimate Windows signed binaries likely used for DLL sideloading.

Additionally, we observed the sample downloading the following malicious files:

• A batch script (SHA-256: 5df4269998ed79fbc997766303759768ce89ff1412550b35ff32e85db3c1f57b)
• A DLL file (SHA-256: fb70ff49411ce04951895977acfc06fa468e4aa504676dedeb40ba5cea76f37f)
• A DLL file (SHA-256: 711d3deccc22f5acfd3a41b8c8defb111db0f2b474febdc7f20a468f67db0350)

The batch script adds a registry Run key for a file called SharePoint.exe, likely used to load the malicious DLL files above, thus setting up persistence:

The two DLL files are both 64-bit C/C++ compiled PE DLL files and appear to be functionally identical to the previously analyzed samples. As fully functional backdoors, they can run the following commands:

• systeminfo – Gather system information
• dir – List directory
• run – Execute command
• delete – Delete file
• interval – Sleep interval
• upload – Download file from the C2
• download – Upload file to the C2

Azure resources abuse

Microsoft observed Peach Sandstorm creating Azure tenants using Microsoft Outlook email accounts and creating Azure for Students subscriptions in these tenants. Additionally, the group leveraged compromised user accounts in the Azure tenants of organizations in the education sector to do the same. Within these subscriptions, Peach Sandstorm subsequently created Azure resources for use as C2 for the backdoor. Of note, we have observed multiple Iranian groups, including Smoke Sandstorm, use similar techniques in recent months. The following resources were created by Peach Sandstorm for use as Tickler C2 nodes:

• subreviews.azurewebsites[.]net 
• satellite2.azurewebsites[.]net 
• nodetestservers.azurewebsites[.]net 
• satellitegardens.azurewebsites[.]net 
• softwareservicesupport.azurewebsites[.]net
• getservicessuports.azurewebsites[.]net
• getservicessupports.azurewebsites[.]net 
• getsupportsservices.azurewebsites[.]net 
• satellitespecialists.azurewebsites[.]net
• satservicesdev.azurewebsites[.]net
• servicessupports.azurewebsites[.]net
• websupportprotection.azurewebsites[.]net 
• supportsoftwarecenter.azurewebsites[.]net
• centersoftwaresupports.azurewebsites[.]net
• softwareservicesupports.azurewebsites[.]net
• getsdervicessupoortss.azurewebsites[.]net

Post-compromise activity

In the past year, Peach Sandstorm has successfully compromised several organizations, primarily in the aforementioned sectors, using bespoke tooling. Once Peach Sandstorm gains access to an organization, the threat actor is known to perform lateral movement and actions on objectives using the following techniques:

Moving laterally via Server Message Block (SMB)

After compromising a European defense organization, Peach Sandstorm threat actors moved laterally via SMB. SMB lateral movement is a technique used by threat actors to move from one compromised machine to another within a network by exploiting the SMB protocol. This protocol, which is used for sharing files, printers, and other resources on a network, could be misused by attackers to propagate their access and gain control over multiple systems.

Downloading and installing a remote monitoring and management (RMM) tool

In an older intrusion against a multinational pharmaceutical company not associated with the campaign discussed in this blog, after a likely successful password spray attack, Peach Sandstorm attempted to download and install AnyDesk, a commercial RMM tool. AnyDesk has a range of capabilities that allow users to remotely access a network, persist in a compromised environment, and enable command and control. The convenience and utility of a tool like AnyDesk is amplified by the fact that it might be permitted by application controls in environments where it is used legitimately by IT support personnel or system administrators.

Taking an Active Directory (AD) snapshot

In at least one intrusion against a Middle East-based satellite operator, Peach Sandstorm actors compromised a user using a malicious ZIP file delivered via Microsoft Teams message followed by dropping AD Explorer and taking an AD snapshot. An AD snapshot is a read-only, point-in-time copy of the AD database and related files, which can be used for various legitimate administrative tasks. These snapshots can also be exploited by threat actors for malicious purposes.

Mitigations

To harden networks against Peach Sandstorm activity, defenders can implement the following:

• Reset account passwords for any accounts targeted during a password spray attack. If a targeted account had system-level permissions, further investigation may be warranted. 
• Revoke session cookies in addition to resetting passwords. 
  • Revoke any MFA setting changes made by the attacker on any compromised users’ accounts. 
  • Require re-challenging MFA for MFA updates as the default. 
• Implement the Azure Security Benchmark and general best practices for securing identity infrastructure, including:  
  • Create conditional access policies to allow or disallow access to the environment based on defined criteria. 
  • Block legacy authentication with Microsoft Entra by using Conditional Access. Legacy authentication protocols don’t have the ability to enforce multifactor authentication (MFA), so blocking such authentication methods will help prevent password spray attackers from taking advantage of the lack of MFA on those protocols. 
  • Enable AD FS web application proxy extranet lockout to protect users from potential password brute force compromise. 
• Secure accounts with credential hygiene: 
  • Practice the principle of least privilege and audit privileged account activity in your Microsoft Entra environments to help slow and stop attackers.  
  • Deploy Microsoft Entra Connect Health for Active Directory Federation Services (AD FS). This captures failed attempts as well as IP addresses recorded in AD FS logs for bad requests in the Risky IP report. 
  • Use Microsoft Entra password protection to help detect and block known weak passwords and their variants. 
  • Turn on identity protection in Microsoft Entra to monitor for identity-based risks and create policies for risky sign ins. 
• Comply with the recent MFA enforcement policy requiring all Azure accounts to utilize MFA. Keep MFA always-on for privileged accounts and apply risk-based MFA for normal accounts.
  • Consider transitioning to a passwordless primary authentication method, such as Azure MFA, certificates, or Windows Hello for Business. 
• Secure remote desktop protocol (RDP) or Windows Virtual Desktop endpoints with MFA to harden against password spray or brute force attacks.

To protect against password spray attacks, implement the following mitigations:

• Eliminate insecure passwords.
• Educate users to review sign-in activity and mark suspicious sign-in attempts as “This wasn’t me”.
• Reset account passwords for any accounts targeted during a password spray attack. If a targeted account had system-level permissions, further investigation may be warranted.
• Detect, investigate, and remediate identity-based attacks using solutions like Microsoft Entra ID Protection.
• Investigate compromised accounts using Microsoft Purview Audit (Premium).
• Enforce on-premises Microsoft Entra Password Protection for Microsoft Active Directory Domain Services.
• Use risk detections for user sign-ins to trigger multifactor authentication or password changes.
• Investigate any possible password spray activity using the password spray investigation playbook.

Strengthen endpoints against attacks by following these steps:

• Turn on cloud-delivered protection in Microsoft Defender Antivirus or the equivalent for your antivirus product to help cover rapidly evolving attacker tools and techniques. 
• Enable real-time protection in Microsoft Defender Antivirus or the equivalent for your antivirus product. 
• Detect and block potentially unwanted applications through Microsoft Defender for Endpoint. 
• Run endpoint detection and response (EDR) in block mode so that Microsoft Defender for Endpoint can help 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 help remediate malicious artifacts that are detected post-compromise. 
• Turn on attack surface reduction rules to help prevent common attack techniques:  
  • Block executable files from running unless they meet a prevalence, age, or trusted list criterion  
  • Block execution of potentially obfuscated scripts 
• Implement anomaly detection policies in Microsoft Defender for Cloud Apps. 
• Enable protections in Microsoft Defender for Endpoint to help safeguard against malicious sites and internet-based threats. 
  • Network protection 
  • Web protection 
• Enable tamper protection within Microsoft Defender for Endpoint to help prevent threat actors from disabling or changing security features, such as virus and threat protection.

Microsoft Defender XDR detections

Microsoft Defender Antivirus

Microsoft Defender Antivirus detects components of this threat as the following malware:

• TrojanDownloader:Win64/Tickler
• Backdoor:Win64/Tickler

Microsoft Defender for Endpoint

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

• Peach Sandstorm actor activity detected

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

• Password spraying
• Unfamiliar Sign-in properties
• An executable file loaded an unexpected DLL file

Microsoft Defender for Identity

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

• Atypical travel
• Suspicious behavior: Impossible travel activity

Microsoft Defender for Cloud Apps

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

• Activity from a Tor IP address
• Suspicious Administrative Activity
• Impossible travel activity
• Multiple failed login attempts
• Activity from an anonymous proxy

Threat intelligence reports

Microsoft Defender Threat Intelligence 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 help prevent, mitigate, or respond to associated threats found in customer environments.

Microsoft Defender Threat Intelligence

• Abuse of remote monitoring and management tools
• DLL sideloading and DLL search order hijacking

Hunting queries

Microsoft Defender XDR

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

Failed logon activity

The following query identifies failed attempts to sign-in from multiple sources that originate from a single ISP. Attackers distribute attacks from multiple IP addresses across a single service provider to evade detection. Run query 

IdentityLogonEvents
| where Timestamp > ago(4h)
| where ActionType == "LogonFailed"
| where isnotempty(AccountObjectId)
| summarize TargetCount = dcount(AccountObjectId), TargetCountry = dcount(Location), TargetIPAddress = dcount(IPAddress) by ISP
| where TargetCount >= 100
| where TargetCountry >= 5
| where TargetIPAddress >= 25

Connectivity to C2s

The following queries identifies connectivity to Peach Sandstorm created Azure App Service apps for command and control. Run query

let domainList = dynamic(["subreviews.azurewebsites.net", 
    "satellite2.azurewebsites.net",
    "nodetestservers.azurewebsites.net", 
    "satellitegardens.azurewebsites.net",
    "softwareservicesupport.azurewebsites.net",
    "getservicessuports.azurewebsites.net",
    "getservicessupports.azurewebsites.net",
    "getsupportsservices.azurewebsites.net",
    "satellitespecialists.azurewebsites.net",
    "satservicesdev.azurewebsites.net",
    "servicessupports.azurewebsites.net",
    "websupportprotection.azurewebsites.net ",
    "supportsoftwarecenter.azurewebsites.net",
    "centersoftwaresupports.azurewebsites.net"
    "softwareservicesupports.azurewebsites.net",
    "getsdervicessupoortss.azurewebsites.net"]);union
(
    DnsEvents
    | where QueryType has_any(domainList) or Name has_any(domainList)
    | project TimeGenerated, Domain = QueryType, SourceTable = "DnsEvents"
),
(
    IdentityQueryEvents
    | where QueryTarget has_any(domainList)
    | project Timestamp, Domain = QueryTarget, SourceTable = "IdentityQueryEvents"
),
(
    DeviceNetworkEvents
    | where RemoteUrl has_any(domainList)
    | project Timestamp, Domain = RemoteUrl, SourceTable = "DeviceNetworkEvents"
),
(
    DeviceNetworkInfo
    | extend DnsAddresses = parse_json(DnsAddresses), ConnectedNetworks = parse_json(ConnectedNetworks)
    | mv-expand DnsAddresses, ConnectedNetworks
    | where DnsAddresses has_any(domainList) or ConnectedNetworks.Name has_any(domainList)
    | project Timestamp, Domain = coalesce(DnsAddresses, ConnectedNetworks.Name), SourceTable = "DeviceNetworkInfo"
),
(
    VMConnection
    | extend RemoteDnsQuestions = parse_json(RemoteDnsQuestions), RemoteDnsCanonicalNames = parse_json(RemoteDnsCanonicalNames)
    | mv-expand RemoteDnsQuestions, RemoteDnsCanonicalNames
    | where RemoteDnsQuestions has_any(domainList) or RemoteDnsCanonicalNames has_any(domainList)
    | project TimeGenerated, Domain = coalesce(RemoteDnsQuestions, RemoteDnsCanonicalNames), SourceTable = "VMConnection"
),
(
    W3CIISLog
    | where csHost has_any(domainList) or csReferer has_any(domainList)
    | project TimeGenerated, Domain = coalesce(csHost, csReferer), SourceTable = "W3CIISLog"
),
(
    EmailUrlInfo
    | where UrlDomain has_any(domainList)
    | project Timestamp, Domain = UrlDomain, SourceTable = "EmailUrlInfo"
),
(
    UrlClickEvents
    | where Url has_any(domainList)
    | project Timestamp, Domain = Url, SourceTable = "UrlClickEvents"
)
| order by TimeGenerated desc

Malicious file activity

The following query will surface events involving malicious files related to this activity. Run query

let fileHashes = dynamic(["711d3deccc22f5acfd3a41b8c8defb111db0f2b474febdc7f20a468f67db0350", "fb70ff49411ce04951895977acfc06fa468e4aa504676dedeb40ba5cea76f37f", "5df4269998ed79fbc997766303759768ce89ff1412550b35ff32e85db3c1f57b", "ccb617cc7418a3b22179e00d21db26754666979b4c4f34c7fda8c0082d08cec4", "7eb2e9e8cd450fc353323fd2e8b84fbbdfe061a8441fd71750250752c577d198"]);
union
(
    DeviceFileEvents
    | where SHA256 in (fileHashes)
    | project Timestamp, FileHash = SHA256, SourceTable = "DeviceFileEvents"
),
(
    DeviceEvents
    | where SHA256 in (fileHashes)
    | project Timestamp, FileHash = SHA256, SourceTable = "DeviceEvents"
),
(
    DeviceImageLoadEvents
    | where SHA256 in (fileHashes)
    | project Timestamp, FileHash = SHA256, SourceTable = "DeviceImageLoadEvents"
),
(
    DeviceProcessEvents
    | where SHA256 in (fileHashes)
    | project Timestamp, FileHash = SHA256, SourceTable = "DeviceProcessEvents"
)
| order by Timestamp desc

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.

• Signin Password Spray
• New Location Azure AD Sign Ins
• Enumeration of users & groups for lateral movement
• SMB shares Discovery
• Anomaly in SMB Traffic
• AnyDesk Net Connection
• AnyDesk – File Signature
• AnyDesk – Create Process
• DCSync Attack Detection

Indicators of compromise

Domains

• subreviews.azurewebsites[.]net 
• satellite2.azurewebsites[.]net 
• nodetestservers.azurewebsites[.]net 
• satellitegardens.azurewebsites[.]net 
• softwareservicesupport.azurewebsites[.]net
• getservicessuports.azurewebsites[.]net
• getservicessupports.azurewebsites[.]net 
• getsupportsservices.azurewebsites[.]net 
• satellitespecialists.azurewebsites[.]net
• satservicesdev.azurewebsites[.]net
• servicessupports.azurewebsites[.]net
• websupportprotection.azurewebsites[.]net 
• supportsoftwarecenter.azurewebsites[.]net
• centersoftwaresupports.azurewebsites[.]net
• softwareservicesupports.azurewebsites[.]net
• getsdervicessupoortss.azurewebsites[.]net

Tickler samples and related indicators

• YAHSAT NETWORK_INFRASTRUCTURE_SECURITY_GUIDE_20240421.pdf.exe (SHA-256:  7eb2e9e8cd450fc353323fd2e8b84fbbdfe061a8441fd71750250752c577d198)
• Sold.dll (SHA-256: ccb617cc7418a3b22179e00d21db26754666979b4c4f34c7fda8c0082d08cec4)
• Batch script (SHA-256: 5df4269998ed79fbc997766303759768ce89ff1412550b35ff32e85db3c1f57b)
• Malicious DLL (SHA-256: fb70ff49411ce04951895977acfc06fa468e4aa504676dedeb40ba5cea76f37f)
• Malicious DLL (SHA-256: 711d3deccc22f5acfd3a41b8c8defb111db0f2b474febdc7f20a468f67db0350)

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 and on X (formerly Twitter) at https://twitter.com/MsftSecIntel.

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 Peach Sandstorm deploys new custom Tickler malware in long-running intelligence gathering operations appeared first on Microsoft Security Blog.

OpenVPN is widely used by thousands of companies spanning various industries across major platforms such as Windows, iOS, macOS, Android, and BSD. As such, exploitation of the discovered vulnerabilities, which affect all versions of OpenVPN prior to version 2.6.10 (and 2.5.10), could put endpoints and enterprises at significant risk of attack.

We reported the discovery to OpenVPN through Coordinated Vulnerability Disclosure (CVD) via Microsoft Security Vulnerability Research (MSVR) in March 2024 and worked closely with OpenVPN to ensure that the vulnerabilities are patched. Information on the security fixes released by OpenVPN to address these vulnerabilities can be found here: OpenVPN 2.6.10. We strongly urge OpenVPN users to apply the latest security updates as soon as possible. We also thank OpenVPN for their collaboration and recognizing the urgency in addressing these vulnerabilities.

Below is a list of the discovered vulnerabilities discussed in this blog:

In this blog post, we detail our analysis of the discovered vulnerabilities and the impact of exploitation. In addition to patching, we provide guidance to mitigate and detect threats attempting to exploit these vulnerabilities. This research emphasizes the need for responsible disclosure and collaboration among the security community to defend devices across platforms and build better protection for all, spanning the entire user-device ecosystem. The discovery of these vulnerabilities further highlights the critical importance of ensuring the security of enterprise and endpoint systems and underscores the need for continuous monitoring and protection of these environments.

What is OpenVPN?

OpenVPN is a virtual private network (VPN) system that creates a private and secure point-to-point or site-to-site connection between networks. The OpenVPN open-source project is widely popular across the world, including the United States, India, France, Brazil, the United Kingdom, and Germany, as well as industries spanning the information technology, financial services, telecommunications, and computer software sectors. This project supports different major platforms and is integrated into millions of devices globally.

OpenVPN is also the name of the tunneling protocol it uses, which employs the Secure Socket Layer (SSL) encryption protocol to ensure that data shared over the internet remains private, using AES-256 encryption. Since the source code is available for audit, vulnerabilities can be easily identified and fixed.

OpenVPN analysis

We discovered the vulnerabilities while examining the OpenVPN open-source project to enhance enterprise security standards. During this research, we checked two other popular VPN solutions and found that at the time they were impacted by a vulnerability (CVE-2024-1305). Following this discovery, we started hunting for and uncovered additional vulnerable drivers with the same issue and decided to investigate open-source VPN projects. Upon confirming that the same vulnerability was located in the OpenVPN open-source repository, our research then focused on examining the architecture and security model of the OpenVPN project for Windows systems.

OpenVPN architecture

OpenVPN server client architecture

OpenVPN is a sophisticated VPN system meticulously engineered to establish secure point-to-point or site-to-site connections. It supports both routed and bridged configurations, as well as remote access capabilities, making it a versatile choice for various networking needs. OpenVPN comprises both client and server applications, ensuring a comprehensive solution for secure communication.

With OpenVPN, peers can authenticate each other through multiple methods, including pre-shared secret keys, certificates, or username/password combinations. In multi-client server environments, the server can generate and issue an individual authentication certificate for each client, leveraging robust digital signatures and a trusted certificate authority. This ensures an elevated level of security and integrity in the authentication process, enhancing the overall reliability of the VPN connection. 

Client-side architecture

The client-side architecture is where we discovered the additional three vulnerabilities (CVE-2024-27459, CVE-2024-24974, and CVE-2024-27903):

OpenVPN’s client architecture can be summarized in the following simplified diagram:

openvpnserv.exe and openvpn.exe

The system service launches elevated commands on behalf of the user, handling tasks such as adding or deleting DNS configurations, IP addresses, and routes, and enabling Dynamic Host Configuration Protocol (DHCP). These commands are received from the openvpn.exe process through a named pipe created for these two entities, such as “openvpn/service_XXX” where XXX is the thread ID (TID) that is being passed to the newly created process as a command line argument.

The launched commands arrive in the form of a binary structure that contains the relevant information for the specific command, with the structure being validated and only then launching the appropriate command. The below figure displays an example of the structure that contains information for adding/deleting DNS configuration:

Additionally, openvpnserv.exe serves as the management unit, spawning openvpn.exe processes upon requests from different users on the machine. This can be done automatically using the OpenVPN GUI or by sending specifically crafted requests. Communication for this process occurs through a second named pipe, such as “openvpn/service”.

Openvpn.exe is the user mode process being spawned on behalf of the client. When openvpn.exe starts, it receives a path for a configuration file (as a command line argument). The configuration file that’s provided holds different information.

A lot of fields can be managed in configuration files, such as:

1. Tunnel options
2. Server mode options
3. Client mode options

Plugin mechanism in openvpn.exe

Another mechanism of interest for us is the plugin mechanism in openvpn.exe, which can extend the functionality to add additional logic, such as authentication plugins to bring authentication against Lightweight Directory Access Protocol (LDAP) or Radius or other Pluggable Authentication Module
(PAM) backends. Some of the existing plugins are:

1. Radiusplugin – Radius authentication support for open OpenVPN.
2. Eurephia – Authentication and access control plugin for OpenVPN.
3. Openvpn_defer_auth – OpenVPN plugin to perform deferred authentication requests.

The plugin mechanism fits into the earlier diagram, as shown in Figure 2.

The plugin is loaded as a directive in the configuration file, which looks like:

Furthermore, the number of callbacks defined in the plugin launch on behalf of the loading process (openvpn.exe), such as:

1. openvpn_plugin_func_v1 – This function is called by OpenVPN each time the OpenVPN reaches a point where plugin calls should happen.
2. openvpn_plugin_{open, func}_v3() – Defines the version of the v3 plugin argument.

OpenVPN security model

As previously mentioned, we discovered four vulnerabilities on the client side of OpenVPN’s architecture.

As described before, openvpnserv.exe (SYSTEM service) spawns the openvpn.exe process as a result of the request from the user. Furthermore, the spawned process runs in the context of the user who requested to create the new process, which is achieved through named pipe impersonation, as displayed in the below image:

The ImpersonateNamedPipeClient function impersonates a named pipe client application.

Furthermore, to prevent unwanted behavior, specific EXPLICIT_ACCESS must be granted for any new process:

This explicit access, in addition to the earlier described “elevated commands” launched by openvpnserv.exe on request from the openvpn.exe process, and other comprehensive inspection of the passed arguments  ensure that malicious behavior cannot be launched in the name of the impersonated user.

Vulnerability analysis

CVE-2024-1305    

We identified a vulnerability in the “tap-windows6” project that involves developing the Terminal Access Point (TAP) adapter used by OpenVPN. In the project’s src folder, the device.c file contains the code for the TAP device object and its initialization.

In the device.c file, the CreateTapDevice method initializes a dispatch table object with callbacks for methods managing various Input/Output Controls (IOCTLs) for the device. One of these methods is TapDeviceWrite, which handles the write IOCTL.

The TapDeviceWrite method performs several operations and eventually calls TapSharedSendPacket. This method, in turn, calls NdisAllocateNetBufferAndNetBufferLists twice. In one scenario, it calls this function with the fullLength parameter, defined as follows:

Both PacketLength and PrefixLength are parameters passed from the TapDeviceWrite call and, therefore, attacker controlled. If these values are large enough, their sum (fullLength) can overflow (a 32-bit unsigned integer). This overflow results in the allocation of a smaller-than-expected memory size, which subsequently causes a memory overflow issue.

CVE-2024-27459  

The second vulnerability that we discovered resided in the communication mechanism between the openvpn.exe process and the openvpnserv.exe service. As described earlier, both of which communicate through a named pipe:

The openvpnserv.exe service will read the message size in an infinite loop from the openvpn.exe process and then handle the message received by calling the HandleMessage method. The HandleMessage method reads the size provided by the infinite loop and casts the read bytes into the relevant type accordingly:

This communication mechanism presents an issue as reading the “user” provided number of bytes on to an “n bytes” long structure located on the stack will produce a stack overflow vulnerability.

CVE-2024-24974  

The third vulnerability involves unprivileged access to an operating system resource. The openvpnserv.exe service spawns a new openvpn.exe process based on user requests received through the “\\openvpn\\service” named pipe. This vulnerability allows remote access to the named service pipe, enabling an attacker to remotely interact with and launch operations on it.

CVE-2024-27903  

Lastly, we identified a vulnerability in OpenVPN’s plugin mechanism that permits plugins to be loaded from various paths on an endpoint device. This behavior can be exploited by attackers to load harmful plugins from these different paths.

Exploiting and chaining the vulnerabilities

All the identified vulnerabilities can be exploited once an attacker gains access to a user’s OpenVPN credentials, which could be accomplished using credential theft techniques, such as purchasing stolen credentials on the dark web, using info-stealing malware, or sniffing network traffic to capture NTLMv2 hashes and then using cracking tools like HashCat or John the Ripper to decode them. The discovered vulnerabilities could then be combined to achieve different exploitation results, or chained together to form a sophisticated attack chain, as detailed in the below sections.

RCE exploitation

We first explored how an attacker could achieve remote code execution (RCE) exploitation using CVE-2024-24974 and CVE-2024-27903.

To successfully exploit these vulnerabilities and achieve RCE, an attacker must first obtain an OpenVPN user’s credentials. The attacker’s device must then launch the NET USE command with the stolen credentials to remotely access the operating system resources and grant the attacker access to the named pipes objects devices.

Next, the attacker can send a “connect” request to the “\\openvpn\\service” named pipe to launch a new instance of openvpn.exe on its behalf.

In the request, a path to a configuration file (\\\\DESKTOP-4P6938I\\share\\OpenVPN\\config\\sample.ovpn) is specified that’s located on the attacker-controlled device. A log path is also provided into which the loaded plugin will write its logs (“–log \\\\\{TARGET_MACHINE_PLACEHOLDER}\\share\\OpenVPN\\log\\plugin_log.txt\).

The provided configuration has instructions to load malicious plugin, as such:

After successful exploitation, the attacker can read the log provided on the attacker-controlled device.

LPE exploitation

Next, we investigated how an attacker could achieve local privilege execution (LPE) using CVE-2024-27459 and CVE-2024-27903. To successfully achieve an LPE exploit in this context, an attacker must load a malicious plugin into the normal launching process of openvpn.exe by using a malicious configuration file.

First, the attacker will connect to a local device “\\openvpn\\service” named pipe with a command that instructs openvpnserv.exe to launch openvpn.exe based on the attacker-provided malicious configuration.

The malicious configuration will include a line like the below example:

For the malicious plugin to successfully communicate with openvpnserv.exe, it must hijack the number of the handle used by openvpn.exe to communicate with the inner named pipe connecting the openvpv.exe process and the openvpnserv.exe service. This can be achieved, for instance, by parsing command line arguments, as displayed below:

This works because when the openvpn.exe process spawns, it’s being passed the TID (as a command line argument) that the inner named pipe (which is being used for communication between this specific OpenVPN instance and the openvpnserv.exe service) will have. For instance, if the inner named pipe created is “\\openvpn\\service_1234” then openvpn.exe will be launched with an extra argument of 1234.

Next, attackers can exploit the stack overflow vulnerability by sending data bigger than the MSG structure. It is important to note that there are stack protection mechanisms in place, called stack canaries, which make exploitation much more challenging. Thus, when triggering the overflow:

After the crash of openvpnserv.exe, the attacker has a slot of time in which they can reclaim the named pipe “\\openvpn\\service”.

If successful, the attacker then poses as the server client side of the named pipe “\\openvpn\\service”. From that moment on, every attempt to connect to the “\\openvpn\\service” named pipe will result in a connection to the attacker. If a privileged enough user, such as a SYSTEM or Administrator user, is connected to the named pipe, the attacker can impersonate that user:

The attacker can then start an elevated process on the user’s behalf, thus achieving LPE.

Chaining it all together

As our research demonstrated, an attacker could leverage at least three of the four discovered vulnerabilities to create exploits to achieve RCE and LPE, which could then be chained together to create a powerful attack chain.

A number of adjustments are needed for the full attack chain to be exploited as presented in this blog post, mainly the malicious payload that crashes openvpnserv.exe and the malicious payload that actually behaves as openvpnserv.exe after openvpnserv.exe is crashed all have to be loaded with the malicious plugin. After successfully achieving LPE, attackers will use different techniques, such as Bring Your Own Vulnerable Driver (BYOVD) or exploiting known vulnerabilities, to achieve a stronger grasp of the endpoint. Through these techniques, the attacker can, for instance, disable Protect Process Light (PPL) for a critical process such as Microsoft Defender or bypass and meddle with other critical processes in the system. These actions enable attackers to bypass security products and manipulate the system’s core functions, further entrenching their control and avoiding detection.

Critical importance of endpoint security in private and enterprise sectors

With OpenVPN being widely used across various vendors, industries, and fields, the presented vulnerabilities may impact numerous sectors, device types, and verticals. Exploiting these vulnerabilities requires user authentication, a deep understanding of OpenVPN’s inner workings, and intermediate knowledge of the operating system. However, a successful attack could significantly impact endpoints in both the private and enterprise sectors. Attackers could launch a comprehensive attack chain on a device using a vulnerable version of OpenVPN, achieving full control over the target endpoint. This control could enable them to steal sensitive data, tamper with it, or even wipe and destroy critical information, causing substantial harm to both private and enterprise environments.

The discovery of these vulnerabilities underscores the importance of responsible disclosure to secure enterprise and endpoint systems, in addition to the collective efforts of the security community to protect devices across various platforms and establish stronger safeguards for everyone. We would like to again thank OpenVPN for their partnership and swift action in addressing these vulnerabilities.

Mitigation and protection guidance

OpenVPN versions prior to 2.5.10 and 2.6.10 are vulnerable to discussed vulnerabilities.

It is recommended to first identify if a vulnerable version is installed and, if so, immediately apply the relevant patch found here: OpenVPN 2.6.10.

Additionally, follow the below recommendations to further mitigate potential exploitation risks affiliated with the discovered vulnerabilities:

• Apply patches to affected devices in your network. Check the OpenVPN website for the latest patches.
• Make sure OpenVPN clients are disconnected from the internet and segmented.
• Limit access to OpenVPN clients to authorized users only. 
• Due to the nature of the CVEs, which still require a username and password, prioritizing patching is difficult. Reduce risk by ensuring proper segmentation, requiring strong usernames and passwords, and reducing the number of users that have writing authentication.

Microsoft Defender XDR detections

Microsoft Defender for Endpoint

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

• Suspicious OpenVPN named pipe activity

Microsoft Defender Vulnerability Management

Microsoft Defender Vulnerability Management surfaces devices that may be affected by the following vulnerabilities used in this threat:

• CVE-2024-27459
• CVE-2024-24974
• CVE-2024-27903
• CVE-2024-1305

Microsoft Defender for IoT

Microsoft Defender for IoT raises alerts for the following vulnerabilities, exploits, and behavior associated with this threat:

• Suspicion of Malicious Activity

Hunting queries

Microsoft Defender XDR

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

This query identifies connection to OpenVPN’s named pipe from remote host:

DeviceEvents  
| where ActionType == "NamedPipeEvent"
| extend JsonAdditionalFields=parse_json(AdditionalFields)
| extend PipeName=JsonAdditionalFields["PipeName"]
| where PipeName == "\\Device\\NamedPipe\\openvpn\\service" and isnotempty( RemoteIP) 

This query identifies image load into OpenVPN’s process from share folder:

DeviceImageLoadEvents 
|where InitiatingProcessFileName == "openvpn.exe" and FolderPath startswith "\\\\"

This query identifies process connect to OpenVPN’s named pipe as server which it is not openvpnserv.exe:

DeviceEvents  
| where ActionType == "NamedPipeEvent"
| extend JsonAdditionalFields=parse_json(AdditionalFields)
| extend PipeName=JsonAdditionalFields["PipeName"], NamedPipeEnd=JsonAdditionalFields["NamedPipeEnd"]
|where PipeName == "\\Device\\NamedPipe\\openvpn\\service" and NamedPipeEnd == "Server" and InitiatingProcessFileName != "openvpnserv.exe"

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. More details on the Content Hub can be found here:  https://learn.microsoft.com/azure/sentinel/sentinel-solutions-deploy.

List of devices with OpenVPN vulnerabilities

DeviceTvmSoftwareVulnerabilities
| where OSPlatform contains "Windows"
| where CveId in ("CVE-2024-27459","CVE-2024-24974","CVE-2024-27903","CVE-2024-1305") 
| project DeviceId,DeviceName,OSPlatform,OSVersion,SoftwareVendor,SoftwareName,SoftwareVersion,
CveId,VulnerabilitySeverityLevel
| join kind=inner ( DeviceTvmSoftwareVulnerabilitiesKB | project CveId, CvssScore,IsExploitAvailable,VulnerabilitySeverityLevel,PublishedDate,VulnerabilityDescription,AffectedSoftware ) on CveId
| project DeviceId,DeviceName,OSPlatform,OSVersion,SoftwareVendor,SoftwareName,SoftwareVersion,
CveId,VulnerabilitySeverityLevel,CvssScore,IsExploitAvailable,PublishedDate,VulnerabilityDescription,AffectedSoftware

Named pipe creation activity of OpenVPN

let PipeNames = pack_array('\\openvpn/service','\\openvpn/service_','openvpn','openvpn/service','\\openvpn\\service_');
DeviceEvents
| where TimeGenerated > ago(30d)
| where ActionType == "NamedPipeEvent"
| where ProcessCommandLine contains "openvpn.exe" or InitiatingProcessCommandLine contains "openvpn.exe"
| extend Fields=parse_json(AdditionalFields)
| where Fields.FileOperation == "File created"
| where Fields.PipeName has_any (PipeNames)
| project TimeGenerated,ActionType,DeviceName,InitiatingProcessAccountDomain,InitiatingProcessAccountName,InitiatingProcessFolderPath,
InitiatingProcessCommandLine,ProcessCommandLine,Fields.FileOperation,Fields.PipeName

Vladimir Tokarev

Microsoft Threat Intelligence Community

References

• https://blackhat.com/us-24/briefings/schedule/#ovpnx–zero-days-leading-to-rce-lpe-and-kce-via-byovd-affecting-millions-of-openvpn-endpoints-across-the-globe-38900
• https://enlyft.com/tech/products/openvpn
• https://github.com/OpenVPN/openvpn/blob/v2.6.10/Changes.rst
• https://github.com/OpenVPN/openvpn/blob/v2.5.10/Changes.rst
• https://forums-new.openvpn.net/forum/announcements/69-release-openvpn-version-2-6-10
• https://openvpn.net/community-downloads/
• https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2024-27459
• https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2024-24974
• https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2024-27903
• https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2024-1305
• https://openvpn.net/as-docs/site-to-site-routing.html#site-to-site-routing
• https://openvpn.net/community-resources/reference-manual-for-openvpn-2-4/
• https://github.com/OpenVPN/openvpn/blob/master/include/openvpn-plugin.h.in
• https://www.lifewire.com/net-use-command-2618096
• https://wikipedia.org/wiki/Stack_buffer_overflow#Stack_canaries
• https://community.openvpn.net/openvpn/wiki/Downloads
• https://www.cisa.gov/secure-our-world/use-strong-passwords

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, and on X (formerly Twitter) at https://twitter.com/MsftSecIntel.

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 Chained for attack: OpenVPN vulnerabilities discovered leading to RCE and LPE appeared first on Microsoft Security Blog.