Armadillov220

Hunt Hypothesis

This YARA rule targets the Armadillo v220 malware family, which is frequently used for initial access and persistence in cloud-native environments. Proactively hunting for this signature allows the SOC to identify compromised workloads or containers before the adversary establishes lateral movement or exfiltrates data within the Azure Sentinel environment.

YARA Rule

rule Armadillov220
{
      meta:
		author="malware-lu"
strings:
		$a0 = { 55 8B EC 6A FF 68 10 12 41 00 68 F4 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

• Scenario: A developer or DevOps engineer uses a version control system (e.g., Git, SVN) or a package manager (e.g., npm, pip, go mod) that downloads source code or libraries containing the specific byte pattern matched by the Armadillov220 YARA rule. This often happens when pulling down open-source projects or internal monorepos that include legacy binaries or specific embedded strings.

  • Filter/Exclusion: Exclude file paths under standard development directories such as C:\Users\<user>\.git\, C:\Users\<user>\.npm\, C:\Users\<user>\.cache\pip\, or C:\src\ (if using a centralized build server). Additionally, exclude processes like git.exe, npm.exe, or python.exe when they are writing to these specific cache or repository folders.

• Scenario: An automated backup or snapshot utility (e.g., Veeam, Commvault, or Windows Server Backup) creates compressed archives (.zip, .tar.gz, .vbk) that contain binary files matching the YARA signature. Since YARA rules often match on raw byte sequences, compressed or archived files can trigger detections if the underlying data contains the pattern, especially if the archive is not fully decompressed before scanning.

  • Filter/Exclusion: Exclude file extensions associated with backup tools (.vbk, .vib, .zip, .tar, .7z) when the parent process is a known backup agent (e.g., veeamagent.exe, commvaultagent.exe, wbadmin.exe). Alternatively, configure the YARA scanner to skip compressed files unless explicitly configured to decompress and scan.

• Scenario: A third-party application installer or updater (e.g., setup.exe for Adobe Creative Cloud, Java JRE, or .