Armadillov190b2

Hunt Hypothesis

This rule detects the presence of the Armadillo malware family, a known threat actor often associated with initial access and reconnaissance activities. Proactively hunting for this signature allows the SOC team to identify compromised endpoints early, potentially limiting lateral movement and data exfiltration before the adversary establishes a persistent foothold.

YARA Rule

rule Armadillov190b2
{
      meta:
		author="malware-lu"
strings:
		$a0 = { 55 8B EC 6A FF 68 F0 C1 40 00 68 A4 89 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 developer or DevOps engineer is performing a local build or test of a custom C/C++ application that includes the specific string or byte pattern defined in the Armadillov190b2 YARA rule (e.g., a hardcoded GUID, API function name, or unique marker used for internal licensing or debugging).
  • Filter/Exclusion: Exclude files located in standard development directories such as C:\Users\<User>\Documents\Projects\, C:\src\, or C:\build\ where the file extension is .exe, .dll, or .obj and the parent folder name contains keywords like dev, test, build, or src.
• Scenario: An IT administrator is deploying a custom internal utility or a patched version of a third-party tool (e.g., a modified Sysinternals tool or a custom PowerShell wrapper) that was compiled with a specific linker flag or embedded metadata that matches the YARA signature.
  • Filter/Exclusion: Exclude executables in the C:\Program Files\InternalTools\ or C:\Program Files (x86)\InternalTools\ directories, or specifically exclude files with names matching *internal*.exe or *custom*.dll if they are signed by the organization’s internal code-signing certificate.
• Scenario: A security team is running a YARA scanning engine (such as yara CLI or YARA-Native) against a corpus of test files or a known-good baseline to validate detection rules, where the test files intentionally contain the pattern to verify the rule’s accuracy.
  • Filter/Exclusion: Exclude files located in the security team’s working directory, such as C:\Security\YARA_Rules\TestCases\ or `C:\Temp\YARA_Scan\