PEArmor04600759hying

Hunt Hypothesis

This YARA rule targets specific PE file characteristics associated with the “PEArmor” signature, potentially indicating the presence of packed or obfuscated executables that adversaries use to evade static analysis. Proactively hunting for these artifacts in Azure Sentinel allows the SOC team to identify suspicious binaries deployed in workloads or endpoints before they can be executed to establish persistence or launch further malicious payloads.

YARA Rule

rule PEArmor04600759hying
{
      meta:
		author="malware-lu"
strings:
		$a0 = { 00 00 00 00 00 00 00 00 [8] 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 [12] 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 64 64 72 65 73 73 00 00 00 47 65 74 4D 6F 64 75 6C 65 48 61 6E 64 6C 65 41 00 00 00 4C 6F 61 64 4C 69 62 72 61 72 79 41 00 }

condition:
		$a0
}

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

• Legacy Java Application Deployment: Enterprise Java applications (e.g., legacy ERP systems or internal portals) often bundle custom JAR files or native libraries that may contain specific byte patterns or obfuscated headers resembling the PEArmor04600759hying signature. This is common in environments using Apache Tomcat or JBoss where WAR/EAR files are unpacked during deployment.

  • Filter/Exclusion: Exclude files located in standard application server directories (e.g., C:\Program Files\Apache Tomcat\, C:\jboss\) or filter by file extension .jar, .war, .ear if the YARA rule targets PE headers, ensure the rule does not scan non-PE binaries or add an exception for known Java runtime paths.

• Third-Party SDK and Library Updates: Development teams frequently install or update third-party C/C++ SDKs (e.g., Intel OpenCL, NVIDIA CUDA, or DirectX SDK) which include numerous small, statically linked PE executables or DLLs. These libraries may be digitally signed but retain specific compiler artifacts or padding bytes that trigger the YARA pattern.

  • Filter/Exclusion: Exclude files within standard SDK installation paths (e.g., C:\Program Files (x86)\Microsoft SDKs\, C:\Program Files\NVIDIA GPU Computing Toolkit\) or filter by known publisher names (e.g., “NVIDIA Corporation”, “Intel Corporation”) if the YARA rule includes metadata checks.

• Scheduled Backup and Archiving Jobs: Enterprise backup solutions like Veeam, Commvault, or Acronis create temporary PE-like container files or snapshot metadata during scheduled backup windows. These files may be written to temp directories or scratch space with specific block signatures that match the YARA rule, especially if the rule targets specific section headers