Armadillov19x

Hunt Hypothesis

This rule detects the presence of the Armadillo v19x malware family, a known threat actor tool often used for initial access and lateral movement in enterprise environments. Proactively hunting for this signature allows the SOC to identify compromised endpoints early, potentially before the adversary establishes persistence or exfiltrates sensitive data.

YARA Rule

rule Armadillov19x
{
      meta:
		author="malware-lu"
strings:
		$a0 = { 55 8B EC 6A FF 68 98 [3] 68 10 [3] 64 A1 [4] 50 64 89 25 [4] 83 EC 58 53 56 57 89 65 E8 FF 15 }

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 security team executes a YARA scan against a large directory of archived logs or backup files using a tool like yarascan or yara CLI, where the rule Armadillov19x matches a benign binary or data file that coincidentally contains the specific byte patterns defined in the rule (e.g., due to compression artifacts or embedded strings).

  • Filter/Exclusion: Exclude processes originating from known YARA scanning tools (e.g., yara.exe, yarascan.exe, yara-python) or exclude file paths under specific backup/archive directories (e.g., \\fileserver\backups\, C:\Archives\) from triggering the alert.

• Scenario: An IT administrator runs a legitimate software installer or updater for a vendor application that bundles a component matching the Armadillov19x signature (e.g., a specific version of a Java JRE, .NET framework, or a proprietary SDK) during a scheduled patch Tuesday deployment.

  • Filter/Exclusion: Whitelist specific executable names associated with known vendors (e.g., msiexec.exe, setup.exe from specific vendor paths) or exclude alerts if the parent process is a known installation service (e.g., wuauserv, msiexec) and the file location is within standard program files directories (C:\Program Files\, C:\Program Files (x86)\).

• Scenario: A development team uses a containerized build pipeline (e.g., Jenkins, Azure DevOps) that pulls down a base Docker image or container layer containing a library or binary that matches the Armadillov19x YARA rule, and the container runtime (e.g., dockerd, containerd-shim) executes or touches this file during image build or container startup.