Armadillov250

Hunt Hypothesis

This detection identifies potential malware activity matching the Armadillov250 signature through YARA scanning on endpoint files within the Azure Sentinel environment. Proactively hunting for this behavior allows the SOC team to validate false positives and uncover early-stage infections that may not yet trigger high-severity alerts, ensuring comprehensive coverage of low-fidelity threats.

YARA Rule

rule Armadillov250
{
      meta:
		author="malware-lu"
strings:
		$a0 = { 55 8B EC 6A FF 68 B8 [3] 68 F8 [3] 64 A1 00 00 00 00 50 64 89 25 00 00 00 00 83 EC 58 53 56 57 89 65 E8 FF 15 20 [3] 33 D2 8A D4 89 15 D0 }

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

Here are 4 specific false positive scenarios for the Armadillov250 detection rule, including suggested filters and exclusions:

• Scenario: Automated Patch Deployment via Microsoft Endpoint Configuration Manager (SCCM)

  • Context: During scheduled maintenance windows, SCCM pushes security updates or application patches to endpoints. The deployment agent often executes a temporary installer process that matches the Armadillo signature pattern due to its use of embedded scripts and specific file hashing mechanisms.
  • Suggested Filter/Exclusion: Create an exclusion based on the Process Name (e.g., ccmsetup.exe, wuauserv.exe) and restrict it to the specific User Account used by the SCCM service account (e.g., DOMAIN\SCCM-Service). Additionally, limit detection to business hours or exclude the specific scheduled job ID if the rule supports metadata.

• Scenario: Endpoint Backup Operations using Veeam Agent

  • Context: The Veeam Agent for Windows performs incremental backups of critical system state files. During the backup indexing phase, the agent creates temporary staging files and executes a compression routine that triggers the YARA signature associated with Armadillov250, mimicking suspicious file manipulation behavior.
  • Suggested Filter/Exclusion: Exclude the process VeeamAgent.exe (or veeamagent.exe) from detection when running under the local system account (NT SYSTEM). Furthermore, add a path-based exclusion for the default backup staging directory (e.g., C:\ProgramData\Veeam\BackupStaging\*).

• Scenario: Scheduled Antivirus Definition Updates via CrowdStrike Falcon

  • Context: The CrowdStrike Falcon sensor performs hourly definition updates. The update mechanism involves downloading a compressed payload and extracting it using an internal utility that shares code signatures with the Armadillo detection logic