Armadillov190b4

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 the environment. Proactively hunting for this indicator in Azure Sentinel allows the SOC team to uncover early-stage infections that may evade standard signature-based defenses, ensuring rapid containment of low-severity threats before they escalate into broader compromises.

YARA Rule

rule Armadillov190b4
{
      meta:
		author="malware-lu"
strings:
		$a0 = { 55 8B EC 6A FF 68 08 E2 40 00 68 B4 96 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

Here are 5 specific false positive scenarios for the Armadillov190b4 detection rule, including targeted filters and exclusions:

• Scenario: The Microsoft Defender Antivirus engine performs a scheduled daily scan of the C:\Program Files directory. During this process, the scanner extracts compressed archives (.zip, .7z) containing legitimate software updates or patches, triggering the YARA rule which mimics the extraction behavior of the Armadillo malware family.

  • Filter/Exclusion: Add a path-based exclusion for C:\Program Files\Microsoft Defender and exclude processes where the parent process is MsMpEng.exe. Alternatively, create a filter to ignore alerts where the file extension matches .zip, .7z, or .cab within the System32 directory.

• Scenario: The Ansible Tower automation platform executes a nightly deployment job that installs new agent configurations on endpoint servers. This involves copying configuration scripts and binary payloads from a central repository to local temporary folders (C:\Temp\AnsibleDeploy), which generates file creation events matching the Armadillo signature.

  • Filter/Exclusion: Exclude alerts generated by the process ansible-runner.exe or python.exe when running under the user context of ANONYMOUS_LOGON or a dedicated service account like svc_ansible. Additionally, exclude any file paths containing \AnsibleDeploy\ in the detection logic.

• Scenario: The SolarWinds Patch Manager performs an automated update cycle for third-party applications (e.g., Adobe Acrobat, Zoom). During the installation phase, it unpacks installer packages into a temporary staging directory (C:\ProgramData\SolarWinds\PatchManager\Staging), creating a burst of file activity that resembles the malware’s propagation mechanism.

  • Filter/Exclusion: Implement