Armadillov260c

Hunt Hypothesis

This rule identifies the presence of the Armadillo malware family, a known threat actor tool often used for initial access and lateral movement, by matching its specific code signatures within memory or disk artifacts. Proactively hunting for this signature allows the SOC to detect 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 Armadillov260c
{
      meta:
		author="malware-lu"
strings:
		$a0 = { 55 8B EC 6A FF 68 40 [3] 68 F4 [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 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

• Scenario: A developer or DevOps engineer uses Git for Windows or VS Code to clone a large repository or perform a bulk file operation on a network share (e.g., \\fileserver\projects\armadillo-v260c). The YARA rule may match specific byte patterns in binary assets (like .dll or .exe files) or large text files that coincidentally contain the signature, especially if the rule targets common strings or structural patterns found in build artifacts.

  • Filter/Exclusion: Exclude paths under C:\Program Files\Git\, C:\Users\<user>\.vscode\, or specific project directories like \\fileserver\projects\armadillo-v260c\. Additionally, exclude processes like git.exe, code.exe, or msbuild.exe when accessing these paths.

• Scenario: An IT administrator runs a scheduled PowerShell script to clean up temporary files or archive old logs in the C:\Temp\ or D:\Archives\ directories. If the YARA rule scans for specific file headers or content patterns, it might flag legitimate compressed archives (.zip, .tar.gz) or log files that contain the specific byte sequence targeted by the rule, particularly if the rule is not strictly anchored to executable files.

  • Filter/Exclusion: Exclude file extensions like .zip, .tar, .gz, .log, and .tmp. Exclude paths such as C:\Temp\, D:\Archives\, and C:\Windows\Temp\. Consider excluding processes like powershell.exe or tar.exe when operating in these known benign directories.

• Scenario: A security team or QA engineer uses Fiddler, Wireshark, or Burp Suite to capture and analyze HTTP/HTTPS traffic. These tools often