PEArmorV07Xhying

Hunt Hypothesis

This detection identifies potential malicious or suspicious Portable Executable (PE) files that match specific structural signatures defined by the PEArmorV07Xhying YARA rule, indicating possible file-based threats such as trojans or custom malware. Proactive hunting for this signature in Azure Sentinel is essential to uncover low-severity anomalies that may evade standard heuristic scans, allowing analysts to validate early-stage compromises before they escalate into significant incidents.

YARA Rule

rule PEArmorV07Xhying
{
      meta:
		author="malware-lu"
strings:
		$a0 = { 60 E8 00 00 00 00 5D 81 ED [4] 8D B5 [4] 55 56 81 C5 [4] 55 C3 }

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

Here are 5 specific false positive scenarios for the PEArmorV07Xhying detection rule, including suggested filters and exclusions:

• Scenario: Automated Antivirus Definition Updates

  • Context: Enterprise endpoint protection suites (e.g., Microsoft Defender for Endpoint, CrowdStrike Falcon) frequently download new definition packages or signature updates. These updates often manifest as newly compiled PE binaries that match the heuristic patterns of the YARA rule, triggering alerts immediately upon installation.
  • Filter/Exclusion: Exclude processes where the ImageFileName contains known AV vendor names (e.g., MsMpEng.exe, CnsNotify.exe) and the file path resides within standard update directories (e.g., C:\ProgramData\Microsoft\Windows Defender\Updates).

• Scenario: Scheduled System Backup Jobs

  • Context: Nightly backup agents (such as Veeam Agent, Acronis Cyber Protect, or Windows Task Scheduler jobs running wbengine.exe) generate temporary PE executables during the backup window. These tools often create transient binaries to handle compression or encryption tasks that mimic the behavior of the detection rule.
  • Filter/Exclusion: Create a time-based exclusion for alerts occurring between 01:00 and 05:00 local time, specifically filtering out processes initiated by VeeamAgent.exe, AcronisBackupService.exe, or any process running under the SYSTEM account with a command line containing “backup” or “snapshot”.

• Scenario: Software Deployment via Configuration Management

  • Context: IT teams use tools like Microsoft Endpoint Configuration Manager (SCCM/MECM) or Ansible to push software patches and new applications. During deployment, these agents extract installer packages (PE files) to a temporary staging folder before execution, which can trigger the rule due to the “new file”