PseudoSigner02PEProtect09Anorganix

Hunt Hypothesis

This detection identifies potentially malicious executables exhibiting pseudo-signing characteristics associated with PE Protect and Anorganix obfuscation techniques, which adversaries often employ to evade signature-based defenses. Proactively hunting for these artifacts in Azure Sentinel allows the SOC team to uncover stealthy threats that may bypass standard security controls by mimicking legitimate software signatures while harboring hidden malicious payloads.

YARA Rule

rule PseudoSigner02PEProtect09Anorganix
{
      meta:
		author="malware-lu"
strings:
		$a0 = { 52 51 55 57 64 67 A1 30 00 85 C0 78 0D E8 07 00 00 00 58 83 C0 07 C6 90 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 PseudoSigner02PEProtect09Anorganix detection rule, including suggested filters and exclusions:

• Scenario: Legitimate execution of Microsoft Defender Antivirus (or similar EDR) protection modules during scheduled updates.

  • Context: The YARA rule may flag the MsMpEng.exe or associated PEProtect components when they load specific cryptographic signatures that mimic the “PseudoSigner” pattern defined in the Anorganix logic, particularly during the nightly update cycle.
  • Filter/Exclusion: Exclude processes where the parent process is UpdateOrchestrator.exe (Windows Update) or MsMpEng.exe, and the file path contains \Program Files\Microsoft Defender Antivirus\.

• Scenario: Deployment of Sysinternals Process Monitor (ProcMon.exe) or similar forensic tools by Security Engineers.

  • Context: When analysts run local analysis scripts using Sysinternals tools to capture process behavior, the tool’s internal DLLs often utilize a signing structure that triggers the “PseudoSigner” heuristic, appearing as an anomalous PEProtect signature.
  • Filter/Exclusion: Create a whitelist for ProcMon.exe, ProcessExplorer.exe, and LogParser.exe running under user accounts belonging to the Security_Ops or IT_Admin groups.

• Scenario: Automated backup jobs utilizing Veeam Backup & Replication agents on endpoint servers.

  • Context: The Veeam agent (vrb.exe) frequently injects protection modules into memory that utilize a custom signing certificate structure resembling the Anorganix pattern, often triggering during the “Pre-Backup” phase where file integrity checks are performed.
  • Filter/Exclusion: Exclude events where the executable path starts with `C