Armadillov1xxv2xx

Hunt Hypothesis

This hypothesis targets the presence of Armadillo malware variants, a known threat actor framework often used for initial access and lateral movement, by identifying specific code patterns within memory or disk artifacts. Proactively hunting for this signature in Azure Sentinel allows the SOC team to identify compromised endpoints early, potentially before the adversary establishes persistence or escalates privileges, thereby reducing the overall dwell time of the threat.

YARA Rule

rule Armadillov1xxv2xx
{
      meta:
		author="malware-lu"
strings:
		$a0 = { 55 8B EC 53 8B 5D 08 56 8B 75 0C 57 8B 7D 10 85 F6 }

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 a Python-based build tool or a specific CI/CD pipeline step (e.g., Jenkins, GitLab CI) that embeds a custom, obfuscated Python script or a compiled Python executable (using PyInstaller or Nuitka) to handle data transformation or API interactions. The YARA rule likely matches the specific byte sequence or string pattern associated with the “Armadillo” variant, which may be a common signature for certain Python packaging tools or specific library versions used in the build process.

  • Filter/Exclusion: Exclude processes where the parent process is a known build agent (e.g., java.exe for Jenkins, node.exe for GitLab CI, or docker.exe) and the file path resides within a designated build or workspace directory (e.g., C:\Jenkins\workspace\, C:\gitlab-runner\builds\). Additionally, consider excluding files with extensions like .pyd, .so, or .dll if the rule is primarily targeting executables, or add a specific hash exclusion for the known legitimate build tool binary.

• Scenario: An IT administrator runs a legitimate, third-party backup or disk imaging tool (e.g., Veeam Agent, Acronis True Image, or a custom internal utility) that uses a proprietary compression or encryption algorithm. The “Armadillo” signature might be a generic match for a specific cryptographic header or a common library (like a specific version of OpenSSL or a custom zlib variant) that is statically linked into the backup executable.

  • Filter/Exclusion: Exclude processes where the executable name matches known backup software (e.g., veeamagent.exe, acronis.exe, wbadmin.exe) or where the file path is located in standard installation directories for backup solutions (e.g., C:\Program Files\Veeam\, `C:\Program