Armadillov210b2

Hunt Hypothesis

This YARA rule targets specific memory patterns associated with the Armadillo malware family, indicating the presence of a known threat actor’s tooling within the environment. Proactively hunting for this signature allows the SOC to identify low-severity, potentially dormant implants before they are leveraged for lateral movement or data exfiltration in the Azure Sentinel environment.

YARA Rule

rule Armadillov210b2
{
      meta:
		author="malware-lu"
strings:
		$a0 = { 55 8B EC 6A FF 68 18 12 41 00 68 24 A0 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

• Legacy Java Application Deployment: A CI/CD pipeline or manual deployment script uses a standard jar or zip utility to package a legacy Java application that includes a specific version of a third-party library (e.g., an older commons-codec or guava jar) known to match the byte sequence in the Armadillov210b2 signature.
  • Filter/Exclusion: Exclude files with extensions .jar, .war, or .ear located in specific build artifact directories (e.g., C:\builds\artifacts\, /var/lib/jenkins/workspace/) or where the file size is consistent with known library sizes.
• Standard Windows Installer Packages: An IT admin installs a legacy enterprise software suite (e.g., older versions of SAP, Oracle, or specialized medical imaging software) that bundles a compressed installer component containing the specific byte pattern. The YARA rule may be matching a common compression header or embedded resource within the .msi or .cab file.
  • Filter/Exclusion: Exclude files with extensions .msi, .cab, or .msp if they are located in standard installation directories (e.g., C:\Program Files\, C:\ProgramData\) and were created by a known service account (e.g., svc_installer, DOMAIN\IT_Admin).
• Virtual Machine Snapshot Metadata: A hypervisor (e.g., VMware ESXi or Hyper-V) creates a snapshot or backup of a virtual machine disk image (.vmdk, .vhdx, or .avhd). The YARA scan runs against the raw disk image file, which contains the same application data as the live system, triggering the rule due to the embedded application binary or library.
  • Filter/Exclusion: Exclude files with extensions .vmdk, `.vhdx