Armadillov172v173

Hunt Hypothesis

This hunt hypothesis targets adversaries leveraging the Armadillo malware family (versions 172 and 173) to establish persistent access or execute malicious payloads within the environment. Proactively hunting for this signature in Azure Sentinel is essential because its low severity classification may cause it to be overlooked during routine monitoring, necessitating a dedicated search to identify early-stage infections before they escalate into critical incidents.

YARA Rule

rule Armadillov172v173
{
      meta:
		author="malware-lu"
strings:
		$a0 = { 55 8B EC 6A FF 68 E8 C1 [2] 68 F4 86 [2] 64 A1 [4] 50 64 89 25 [4] 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 5 specific false positive scenarios for the Armadillov172v173 detection rule, including suggested filters and exclusions:

• Scenario: Scheduled Antivirus Definition Updates

  • Context: The enterprise’s endpoint protection suite (e.g., CrowdStrike Falcon or Microsoft Defender) performs a nightly scheduled job to download and install new virus definition signatures. During this process, the update service (mpcmd.exe or FalconSensorService) spawns child processes that match the Armadillo signature pattern due to similar memory usage and file hashing behaviors.
  • Filter/Exclusion: Configure an exclusion based on the parent process name. Exclude alerts where the parent process is MpCmdG.exe (Microsoft Defender) or FalconSensorService.exe (CrowdStrike), provided the execution time falls within the defined maintenance window (e.g., 02:00 – 04:00 UTC).

• Scenario: Automated Patch Deployment via SCCM/Intune

  • Context: During a weekly patch cycle, System Center Configuration Manager (SCCM) or Microsoft Intune pushes updates to workstations. The deployment agent (ccmsetup.exe or IntuneManagementExtension) executes scripts that invoke the Armadillo detection logic while unpacking .msi packages and writing temporary files to the %TEMP% directory.
  • Filter/Exclusion: Create a rule exclusion for paths containing \ProgramData\Microsoft\ConfigurationManager\ or \AppData\Local\Temp\. Additionally, filter alerts where the user context is SYSTEM or a dedicated service account (e.g., DOMAIN\PatchDeploySvc) rather than an interactive logged-in user.

• Scenario: Backup Agent File Indexing

  • Context: Enterprise backup solutions like Veeam Agent for Windows or Acronis Cyber