Armadillov300a

Hunt Hypothesis

This YARA rule targets specific memory patterns or code artifacts associated with the Armadillov300a signature, potentially indicating the presence of a low-severity threat actor or benign software component in process memory. Proactively hunting for this signature allows the SOC team to identify subtle or dormant footholds that may not trigger high-fidelity alerts, ensuring comprehensive coverage of the attack surface in Azure Sentinel.

YARA Rule

rule Armadillov300a
{
      meta:
		author="malware-lu"
strings:
		$a0 = { 60 E8 [4] 5D 50 51 EB 0F B9 EB 0F B8 EB 07 B9 EB 0F 90 EB 08 FD EB 0B F2 EB F5 EB F6 F2 EB 08 FD EB E9 F3 EB E4 FC E9 59 58 50 51 EB }

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 runs a local build script using make or cmake on a Windows workstation, which invokes the armadillo linear algebra library compilation process (e.g., via C++ compiler flags or specific object file names containing “armadillo”).
  • Filter/Exclusion: Exclude processes where the parent process is a compiler (e.g., cl.exe, gcc.exe, msbuild.exe) or where the command line contains build-related keywords like /c, /compile, or paths ending in build\ or obj\.
• Scenario: An IT administrator installs or updates a third-party application (such as a scientific computing tool, machine learning framework, or data analysis suite) that bundles the Armadillo C++ library as a dependency, causing the YARA rule to match the static library file (libarmadillo.a or armadillo.lib) or the associated DLL during the installation or extraction phase.
  • Filter/Exclusion: Exclude file paths located in standard installation directories (e.g., C:\Program Files\, C:\Program Files (x86)\) or exclude files with extensions .lib, .a, or .dll if the parent process is an installer (e.g., msiexec.exe, setup.exe, 7z.exe).
• Scenario: A scheduled backup or snapshot job (e.g., Veeam, Commvault, or Windows Server Backup) reads memory or disk sectors of a running application that has loaded the Armadillo library, causing the YARA scanner to match the in-memory image or the backed-up file copy in the backup repository.
  • Filter/Exclusion: Exclude processes or file paths associated with known backup agents (e.g., vssadmin.exe, wbadmin.exe, `VeeamAgent.exe