Armadillov285

Hunt Hypothesis

This rule detects the presence of the Armadillo v285 malware strain, a known threat actor tool often used for initial access or persistence in enterprise environments. Proactively hunting for this signature allows the SOC to identify compromised hosts early, minimizing the potential for lateral movement or data exfiltration before the adversary establishes a foothold.

YARA Rule

rule Armadillov285
{
      meta:
		author="malware-lu"
strings:
		$a0 = { 55 8B EC 6A FF 68 68 [3] 68 [4] 64 A1 [4] 50 64 89 25 [4] 83 EC 58 53 56 57 89 65 E8 FF 15 28 [3] 33 D2 8A D4 89 15 24 }

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 security team executes a YARA scan using yara or yara64 against a large directory of application binaries (e.g., C:\Program Files\MyApp\bin) to identify known malware signatures. The rule Armadillov285 matches a legitimate DLL that shares a specific byte sequence or string pattern with the target malware, causing the scanner to flag the file as infected.
  • Filter/Exclusion: Exclude processes where the parent process is yara.exe or yara64.exe, or exclude file paths under standard YARA rule directories (e.g., C:\YARA\, C:\Tools\YARA\) and common scan output directories.
• Scenario: An IT administrator runs a full-system disk image or memory dump using tools like FTK Imager, Autopsy, or WinPMEM for forensic analysis. The Armadillov285 rule matches a section of the raw disk image or memory file because it contains embedded code or strings from previously installed software that coincidentally matches the YARA pattern.
  • Filter/Exclusion: Exclude file extensions associated with forensic artifacts (.img, .dmp, .mem, .raw) and exclude processes like ftkimg.exe, autopsy.exe, or winpmem.exe from triggering the alert unless they are executing from non-standard locations.
• Scenario: A development team uses a build automation script (e.g., PowerShell or Python) to compile and package a new version of an internal application. The script invokes a compiler or linker (e.g., cl.exe, link.exe, or msbuild.exe) which temporarily writes intermediate object files or debug symbols that contain code patterns matching the Armadillov285 signature.
  • **Filter/Ex