Armadillov260a

Hunt Hypothesis

This YARA rule targets specific memory patterns associated with the Armadillo malware family, indicating potential in-memory execution or obfuscated code that may evade traditional signature-based detection. Proactively hunting for these indicators in Azure Sentinel allows the SOC to identify stealthy, low-severity threats that often reside in memory without triggering immediate alerts, thereby reducing the dwell time of persistent adversaries.

YARA Rule

rule Armadillov260a
{
      meta:
		author="malware-lu"
strings:
		$a0 = { 55 8B EC 6A FF 68 [4] 68 94 [3] 64 A1 [4] 50 64 89 25 [4] 83 EC 58 53 56 57 89 65 E8 FF 15 6C [3] 33 D2 8A D4 89 15 B4 }

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 developer or IT administrator runs a local build script using Node.js or Python that includes a dependency on a library with a name or version string matching the pattern (e.g., armadillo library for linear algebra or a custom internal module named armadillo-v260a).
  • Filter/Exclusion: Exclude processes where the parent process is node.exe, python.exe, or npm.exe, and the file path contains node_modules or site-packages.
• Scenario: A scheduled maintenance job using PowerShell or Batch scripts invokes a custom internal utility binary or script named armadillov260a.exe or armadillov260a.ps1 for log rotation or database cleanup tasks.
  • Filter/Exclusion: Exclude events where the command line contains keywords like cleanup, rotate, backup, or maintenance, and the process is launched by Task Scheduler (svchost.exe with Task Scheduler service) or schtasks.exe.
• Scenario: A CI/CD pipeline agent (e.g., Jenkins, Azure DevOps, or GitHub Actions) executes a build step that downloads or compiles a component with the identifier Armadillov260a as part of a dependency resolution or artifact staging process.
  • Filter/Exclusion: Exclude processes running under the CI/CD agent user account (e.g., jenkins, azuredevops, github-actions) or where the working directory is within the agent workspace (e.g., C:\jenkins\workspace\, D:\azuredevops\agent\_work\).
• Scenario: An endpoint detection tool or antivirus (e.g., CrowdStrike Falcon, **Microsoft