Armadillov180

Hunt Hypothesis

This detection identifies potential malicious activity associated with the Armadillo malware family by leveraging a specific YARA signature to scan for known code patterns within Azure Sentinel workloads. Proactive hunting is essential because this rule operates at a low severity level, meaning it may not trigger high-priority alerts on its own and requires manual investigation to uncover early-stage infections or lateral movement that automated rules might overlook.

YARA Rule

rule Armadillov180
{
      meta:
		author="malware-lu"
strings:
		$a0 = { 55 8B EC 6A FF 68 E8 C1 00 00 68 F4 86 00 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

Here are 4 specific false positive scenarios for the Armadillov180 detection rule, including suggested filters and exclusions:

• Scenario: Legitimate Antivirus Signature Updates

  • Context: The YARA rule may flag the background update process of enterprise endpoint protection suites (e.g., CrowdStrike Falcon, Microsoft Defender for Endpoint, or Symantec Endpoint Protection) as suspicious when they download and unpack new definition signature files. These processes often involve creating temporary archives that match Armadillo’s heuristic patterns.
  • Filter/Exclusion: Add a process exclusion for the specific update service executables (e.g., C:\Program Files\CrowdStrike\FalconSensor\csfalcon.exe or MsMpSvc) and exclude file paths containing \Updates\ or \Definitions\.

• Scenario: Scheduled Backup Agent Activity

  • Context: Enterprise backup solutions like Veeam Backup & Replication, Rubrik, or Acronis Cyber Protect frequently compress data into .zip, .tar, or proprietary archive formats during nightly scheduled jobs. If the Armadillov180 rule detects specific compression headers or embedded scripts within these archives, it may trigger a false alert on legitimate backup agents running under the SYSTEM account.
  • Filter/Exclusion: Create an exclusion based on the user context (exclude alerts where User == SYSTEM) and filter out processes with names containing “Backup”, “Agent”, or specific vendor paths like C:\Program Files\Rubrik\.

• Scenario: Software Deployment via Group Policy

  • Context: When IT administrators push software installations using Microsoft Endpoint Configuration Manager (SCCM/MECM) or Intune, the deployment engine often extracts installer packages (MSI/EXE) to a temporary staging folder. The extraction