PseudoSigner01PENinja131Anorganix

Hunt Hypothesis

This hunt hypothesis targets adversaries leveraging specific code signing artifacts identified by the PseudoSigner01PENinja131Anorganix YARA rule to mask malicious binaries within legitimate processes. Proactively hunting for this behavior in Azure Sentinel is essential to detect early-stage supply chain compromises or living-off-the-land attacks that utilize pseudo-signed executables to evade standard signature-based defenses.

YARA Rule

rule PseudoSigner01PENinja131Anorganix
{
      meta:
		author="malware-lu"
strings:
		$a0 = { 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 E9 }

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 PseudoSigner01PENinja131Anorganix detection rule, including suggested filters and exclusions tailored for a legitimate enterprise environment:

• Scenario: Automated Patch Deployment via Microsoft Endpoint Configuration Manager (SCCM)

  • Context: During scheduled maintenance windows, SCCM pushes cumulative updates or security patches to endpoints. The deployment agent often executes scripts that generate temporary pseudo-signatures matching the Anorganix profile before the final certificate is applied by the OS kernel.
  • Suggested Filter/Exclusion: Create a process exclusion for ccmsetup.exe and wuauserv.exe. Additionally, filter alerts where the parent process is CcmExec.exe running during defined maintenance windows (e.g., 02:00–04:00 UTC).

• Scenario: Antivirus Engine Scanning by CrowdStrike Falcon

  • Context: The CrowdStrike Falcon sensor performs real-time scanning and heuristic analysis on newly downloaded executables. Its internal engine may temporarily flag legitimate binaries as “PseudoSigner” while the cloud reputation service validates the file, triggering this rule before the final verdict is returned.
  • Suggested Filter/Exclusion: Exclude the detection logic when the parent process is C-0.exe (CrowdStrike Falcon Sensor) or csagent.exe. Implement a time-based suppression for alerts generated within 60 seconds of file creation if the source is the C:\ProgramData\CrowdStrike\ directory.

• Scenario: Scheduled PowerShell Script Execution by IT Operations

  • Context: IT operations teams run nightly cleanup or reporting scripts using PowerShell (powershell.exe) that invoke external tools (e.g., anorganix-cli). These scripts often load unsigned helper modules or temporary DLLs that mimic the signature structure detected by the