Armadillov200b2200b3

Hunt Hypothesis

This rule detects the presence of the Armadillo malware family, a known threat actor tool often used for initial access or lateral movement, by identifying its unique code signatures within memory or disk artifacts. Proactively hunting for this low-severity indicator allows the SOC to identify dormant or stealthy infections that may have evaded traditional network-based detections, ensuring early containment before the adversary establishes a foothold in the Azure environment.

YARA Rule

rule Armadillov200b2200b3
{
      meta:
		author="malware-lu"
strings:
		$a0 = { 55 8B EC 6A FF 68 00 F2 40 00 68 C4 A0 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

• Scenario: A DevOps engineer runs the armadillo CLI tool (a legitimate open-source tool for managing ARM-based deployments or specific vendor-specific ARM utilities) on a build server to validate container images or deploy configurations.
  • Filter/Exclusion: Exclude processes where the parent process is docker.exe, kubectl.exe, or make.exe and the command line contains arguments like --validate, --build, or --deploy. Alternatively, exclude files located in specific development directories such as C:\dev\armadillo\ or C:\tools\armadillo\.
• Scenario: An IT administrator installs or updates a third-party monitoring agent or backup solution (e.g., Veeam, Commvault, or a custom in-house agent) that bundles a component named armadillo.dll or armadillo.exe for its communication or data processing module.
  • Filter/Exclusion: Exclude processes with a digital signature from known vendors (e.g., “Veeam Software,” “Commvault Systems”) or exclude files located in standard installation paths like C:\Program Files\VendorName\ or C:\ProgramData\VendorName\.
• Scenario: A scheduled task runs a custom PowerShell script or batch file named armadillo_task.ps1 or armadillo_cleanup.bat that performs routine log rotation, disk cleanup, or data archival in a non-privileged service account.
  • Filter/Exclusion: Exclude processes where the parent is schtasks.exe or Task Scheduler and the working directory is a known administrative path like C:\Admin\Scripts\ or C:\Services\. Additionally, exclude if the process runs under a dedicated service account (e.g., svc_armadillo) rather than an interactive user.
• Scenario: A developer tests