tElockv071b2

Hunt Hypothesis

This YARA rule targets specific memory or file artifacts associated with the tElockv071b2 signature, indicating the presence of a low-severity threat actor or tooling that may be establishing a foothold or executing initial reconnaissance. Proactively hunting for this pattern in Azure Sentinel allows the SOC team to identify subtle, low-fidelity intrusions that might otherwise slip past high-severity alerts, ensuring early detection of stealthy adversary activity within the environment.

YARA Rule

rule tElockv071b2
{
      meta:
		author="malware-lu"
strings:
		$a0 = { 60 E8 44 11 00 00 C3 83 }

condition:
		$a0 at pe.entry_point
}

Deployment Notes

This YARA rule can be deployed in the following contexts:

• Microsoft Defender for Endpoint — Custom indicators / advanced hunting
• Email Gateway — Attachment scanning
• File Share Monitoring — Periodic scanning of shared drives
• YARA CLI — Manual threat hunting on endpoints

This rule contains 1 string patterns in its detection logic.

• Source Rule

False Positive Guidance

• Scenario: A developer or sysadmin uses 7-Zip (7z.exe) or WinRAR (WinRAR.exe) to compress a large source code directory or log archive for backup or transfer. The YARA rule likely matches the specific byte pattern of the compressed container or the executable itself if it scans memory/disk.

  • Filter/Exclusion: Exclude processes where the parent process is 7z.exe, WinRAR.exe, or tar.exe, and the file extension is .7z, .rar, or .tar.gz. Additionally, exclude paths under C:\Backups\ or D:\Archives\.

• Scenario: An IT administrator runs a scheduled PowerShell script that invokes certutil or bitsadmin to download and extract a software installer (e.g., setup.exe) from a trusted internal repository. The extraction process may trigger the YARA rule if it matches the installer’s binary structure or the temporary extraction folder.

  • Filter/Exclusion: Exclude events where the command line contains certutil -decode or bitsadmin /transfer and the source path is within the internal share \\corp-srv\software\. Also, exclude temporary directories like C:\Windows\Temp\ or %LOCALAPPDATA%\Temp\ for files created within the last 10 minutes.

• Scenario: A CI/CD agent (e.g., Jenkins, GitLab Runner, or Azure DevOps Agent) executes a build step that compiles C/C++ code using gcc or cl.exe and generates a .dll or .exe artifact. The YARA rule may match the linker output or the compiler binary if it scans the build workspace.

  • Filter/Exclusion: Exclude processes spawned by java.exe (Jenkins), gitlab-runner.exe, or `