PEArmor046ChinaCrackingGroup

Hunt Hypothesis

This hypothesis targets the presence of executable files matching the PEArmor046ChinaCrackingGroup YARA signature, indicating potential compromise by a China-based cracking group known for deploying custom malware. Proactively hunting for this indicator allows the SOC to identify low-severity intrusions early, enabling rapid containment before the adversary establishes persistence or exfiltrates data within the Azure environment.

YARA Rule

rule PEArmor046ChinaCrackingGroup
{
      meta:
		author="malware-lu"
strings:
		$a0 = { E8 AA 00 00 00 2D [2] 00 00 00 00 00 00 00 00 00 3D [2] 00 2D [2] 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 4B [2] 00 5C [2] 00 6F [2] 00 00 00 00 00 4B 45 52 4E 45 4C 33 32 2E 64 6C 6C 00 00 00 00 47 65 74 50 72 6F 63 41 }

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 QA engineer uses a portable, unsigned build of 7-Zip or WinRAR for quick file extraction on a jump host or dev box, where the executable is not yet registered in the endpoint inventory or whitelisted by hash.
  • Filter/Exclusion: Exclude executables located in specific development directories (e.g., C:\Dev\Tools\, C:\QA\PortableApps\) or add the specific SHA-256 hash of the known-good portable archive tool to the exclusion list.
• Scenario: An IT administrator runs a legacy, unsigned Windows Update Standalone Installer (wusa.exe) or a custom-built Sysinternals utility (like PsExec or Process Monitor) from a shared network drive or local temp folder to perform maintenance tasks.
  • Filter/Exclusion: Exclude processes initiated by the SYSTEM or Administrators group from paths containing Temp, Downloads, or Shared folders, provided the parent process is a known administrative tool (e.g., cmd.exe, powershell.exe, mstsc.exe).
• Scenario: A marketing or finance team uses an unsigned, lightweight PDF editor (e.g., PDF-XChange Editor portable version) or image converter (e.g., IrfanView portable) that has been downloaded directly from a vendor site rather than installed via the standard MDM/SCCM pipeline.
  • Filter/Exclusion: Exclude executables with names matching common portable app patterns (e.g., *.portable.exe, *Portable.exe) or specific known vendor names (e.g., pdfx.exe, i_rfanview.exe) when executed from user-specific directories (%USERPROFILE%).
• Scenario: A data analyst uses a standalone, unsigned