Armadillov301v305

Hunt Hypothesis

This detection identifies potential malicious activity associated with the Armadillo malware family by leveraging a specific YARA signature to match known behavioral patterns in endpoint logs. A proactive hunt is essential within Azure Sentinel to uncover early-stage infections that may evade standard heuristic controls, ensuring rapid containment before lateral movement occurs across the environment.

YARA Rule

rule Armadillov301v305
{
      meta:
		author="malware-lu"
strings:
		$a0 = { 60 E8 00 00 00 00 5D 50 51 EB 0F B9 EB 0F B8 EB 07 B9 EB 0F 90 EB 08 FD EB 0B F2 EB F5 EB F6 F2 EB 08 FD EB E9 F3 EB E4 FC E9 59 58 50 51 EB 0F B9 EB 0F B8 EB 07 B9 EB 0F 90 EB 08 FD EB 0B F2 EB F5 EB F6 F2 EB 08 FD EB E9 F3 EB E4 FC E9 59 58 50 51 EB 0F }

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: Armadillov301v305

• Scenario 1: Scheduled Antivirus Definition Updates

  • Context: The enterprise’s endpoint protection suite (e.g., Microsoft Defender for Endpoint or CrowdStrike Falcon) automatically downloads and installs daily virus definition updates. These update packages often contain embedded scripts or compressed archives that match the Armadillo signature patterns, triggering a hit on the C:\ProgramData\Antivirus\Updates directory during the scheduled maintenance window (e.g., 02:00 AM).
  • Suggested Filter/Exclusion: Create an exclusion based on the specific process name of the updater service (e.g., MpCmdRun.exe, FalconSensorService.exe) and restrict the scope to the update installation directory path.

• Scenario 2: Deployment of Enterprise Software via SCCM

  • Context: The IT operations team uses Microsoft Endpoint Configuration Manager (SCCM) or Ivanti Neurons to push application patches or new software installations during business hours. The deployment agent extracts installer packages containing embedded YARA-matching components, which are flagged as suspicious activity when the ccmexec.exe process writes temporary files to the %TEMP% folder.
  • Suggested Filter/Exclusion: Exclude alerts where the parent process is ccmexec.exe or IvantiAgentService, specifically targeting file extensions like .msi, .cab, and .zip within the software deployment staging directories (e.g., C:\Windows\CCM\Cache).

• Scenario 3: Automated Backup Jobs via Veeam

  • Context: The nightly backup routine executed by Veeam Backup & Replication creates temporary snapshot files and logs in the shared network storage. The rule detects the creation of these