Armadillov250b3

Hunt Hypothesis

This hypothesis targets the presence of the Armadillo malware family, a known threat actor often associated with initial access or persistence mechanisms that may evade standard signature-based detections. Proactively hunting for this specific YARA pattern allows the SOC to identify compromised endpoints early, reducing the dwell time of adversaries who leverage this tooling for lateral movement or data exfiltration within the Azure environment.

YARA Rule

rule Armadillov250b3
{
      meta:
		author="malware-lu"
strings:
		$a0 = { 55 8B EC 6A FF 68 B8 [3] 68 F8 [3] 64 A1 [4] 50 64 89 25 [4] 83 EC 58 53 56 57 89 65 E8 FF 15 20 [3] 33 D2 8A D4 89 15 D0 }

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 running a local build pipeline or container image creation process (e.g., using docker build or podman build) that compiles C/C++ code or links static libraries. The resulting binary or intermediate object files may contain specific byte sequences or string patterns that match the YARA signature, especially if the build includes debug symbols or specific compiler flags.

  • Filter/Exclusion: Exclude alerts where the parent process is a known build tool (e.g., docker.exe, podman.exe, msbuild.exe, ninja.exe, make.exe) or where the file path resides within standard build directories (e.g., \\build\\, \\dist\\, \\target\\, \\obj\\).

• Scenario: An administrator is performing a disk cleanup or defragmentation task using a tool like CCleaner, Dism++, or Windows built-in defrag.exe. These tools often read and write to large binary files (like .dll, .exe, or .cab archives) in temporary or system directories, which can trigger a YARA rule if the rule targets specific data patterns or entropy levels common in compressed or packed files.

  • Filter/Exclusion: Exclude alerts where the parent process is a known maintenance tool (e.g., ccleaner64.exe, dism++_x64.exe, defrag.exe) or where the file path contains keywords like \\Temp\\, \\Prefetch\\, or \\Windows\\Installer\\.

• Scenario: A security team is performing a vulnerability scan or integrity check using tools like Nessus, Qualys, or ClamAV in their local agent. These scanners often load and analyze binaries in memory or write temporary copies to disk for analysis. If the YARA rule `Armad