Armadillov265b1

Hunt Hypothesis

This hunt hypothesis targets adversaries leveraging the Armadillo malware family to establish persistent footholds within cloud workloads by identifying specific malicious artifacts via the Armadillov265b1 YARA rule. Proactive hunting in Azure Sentinel is essential to detect early-stage infections that may evade standard signature-based defenses, allowing the SOC team to isolate compromised assets before lateral movement occurs.

YARA Rule

rule Armadillov265b1
{
      meta:
		author="malware-lu"
strings:
		$a0 = { 55 8B EC 6A FF 68 38 [3] 68 40 [3] 64 A1 [4] 50 64 89 25 [4] 83 EC 58 53 56 57 89 65 E8 FF 15 28 [3] 33 D2 8A D4 89 15 F4 }

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 Armadillov265b1 detection rule, including actionable filters and exclusions:

• Scenario: Microsoft Defender Antivirus Real-Time Protection Scans

  • Context: The MsMpEng.exe (Microsoft Defender) process frequently scans executable files in the %ProgramFiles% directory. If a legitimate application installer or update package contains code signatures or heuristics similar to the Armadillo artifact, the YARA rule may trigger during routine real-time scanning.
  • Filter/Exclusion: Exclude processes where ProcessName equals MsMpEng.exe and the file path starts with C:\Program Files\Microsoft Defender\. Additionally, add a filter for events occurring within 5 minutes of a scheduled Windows Update installation job.

• Scenario: Enterprise Backup Agent Operations (Veeam/Commvault)

  • Context: Backup agents like Veeam Transport Service or Commvault Command Center often create temporary staging files or extract archives containing embedded scripts that match the Armadillo signature structure. This is common during nightly backup windows when large data sets are processed.
  • Filter/Exclusion: Create an exclusion for processes VeeamTransport.exe and cmdvss.exe. Apply a time-based filter to suppress alerts generated between 02:00 AM and 04:00 AM (local server time) when these backup jobs are typically active.

• Scenario: Software Deployment via SCCM/Intune

  • Context: During the deployment of new enterprise applications, System Center Configuration Manager (SCCM) or Microsoft Intune utilizes ccmsetup.exe to install packages. These packages often include installer wrappers that mimic the behavior and file structure detected by the Armadillo rule, particularly when distributing .msi or .exe payloads.