Armadillov190

Hunt Hypothesis

This rule detects the presence of the Armadillo v190 malware strain, a low-severity threat often associated with initial access or reconnaissance activities. Proactively hunting for this signature allows the SOC team to identify dormant or early-stage infections in Azure Sentinel before they escalate into more impactful lateral movement or data exfiltration events.

YARA Rule

rule Armadillov190
{
      meta:
		author="malware-lu"
strings:
		$a0 = { 55 8B EC 6A FF 68 10 F2 40 00 68 64 9A 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

• Scenario: A legacy Java application (e.g., an internal ERP or CRM system) is deployed via a JAR file that bundles the Armadillo utility for internal data serialization or logging. The YARA rule matches the specific string signature in the armadillo.jar or the extracted class files during a full disk scan or endpoint detection scan.

  • Filter/Exclusion: Exclude file paths containing \lib\ or \jars\ where the filename ends with .jar and the parent directory contains armadillo or serialization. Alternatively, create a specific exclusion for the known SHA256 hash of the legitimate armadillo.jar version used in the environment.

• Scenario: A DevOps engineer uses the armadillo command-line tool (a known utility for ARM assembly disassembly or specific hardware debugging) on a build server or CI/CD agent to analyze firmware binaries. The tool is downloaded from a trusted internal repository and executed in a temporary directory (/tmp or C:\temp\builds\).

  • Filter/Exclusion: Exclude processes or files located in standard build/artifact directories (e.g., C:\builds\, /home/ci/builds/, D:\artifacts\) where the executable name is armadillo or armadillo.exe and the parent process is a build tool (e.g., msbuild.exe, gradle, maven).

• Scenario: A security team performs a scheduled vulnerability scan using a tool like Nessus or Qualys, which includes a plugin that downloads and executes a lightweight armadillo probe to test specific ARM-based endpoints or IoT devices. The probe is a small binary that matches the YARA signature.

  • Filter/Exclusion: Correlate the detection with the parent process being a