Armadillov201

Hunt Hypothesis

This detection identifies potential malware activity matching the Armadillov201 signature through YARA scanning to uncover known threats that may evade standard prevention controls. Proactive hunting for this indicator in Azure Sentinel is essential to validate its presence across endpoints and assess whether low-severity alerts represent isolated incidents or early stages of a broader compromise requiring deeper investigation.

YARA Rule

rule Armadillov201
{
      meta:
		author="malware-lu"
strings:
		$a0 = { 55 8B EC 6A FF 68 08 02 41 00 68 04 9A 40 00 64 A1 00 00 00 00 50 64 89 25 00 00 00 00 83 EC 58 }

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

False Positive Scenarios for Rule: Armadillov201

• Scenario 1: Scheduled Antivirus Definition Updates

  • Context: The enterprise-wide deployment of Microsoft Defender for Endpoint or CrowdStrike Falcon triggers a background service to download and install the latest virus definition signatures during off-peak hours (e.g., 2:00 AM). This process often involves unpacking compressed archives containing new heuristic rules, which mimics the behavior patterns targeted by the Armadillov201 rule.
  • Suggested Filter: Exclude processes running under the specific service accounts used for AV updates (e.g., NT SERVICE\DefenderSvc or CrowdStrike Falcon Service) when the executable path matches the known AV installation directory (C:\Program Files\Microsoft Defender\ or C:\Program Files\CrowdStrike\Falcon).

• Scenario 2: Automated Software Patching via SCCM

  • Context: The System Center Configuration Manager (SCCM) agent executes a scheduled task to deploy critical security patches. During the installation phase, the agent extracts MSI packages and modifies system registry keys related to application whitelisting, which can be flagged as suspicious script execution or file modification by the YARA rule.
  • Suggested Filter: Create an exclusion for processes spawned by ccmexec.exe (the SCCM client) where the command line arguments contain keywords like /install, /update, or specific patch deployment IDs, specifically when running on managed workstations in the “PatchGroup” OU.

• Scenario 3: Admin-Driven Backup and Archiving Jobs

  • Context: A nightly backup job utilizing Veeam Backup & Replication or Acronis Cyber Protect runs to compress large datasets into .zip or proprietary archive formats. The rule detects the creation of