Armadillov184

Hunt Hypothesis

This detection identifies potential malware activity matching the Armadillov184 signature through YARA pattern analysis on endpoint or file artifacts within the Azure Sentinel environment. Proactive hunting for this behavior is essential to uncover early-stage threats that may evade standard rule-based detections, allowing the SOC team to investigate and contain low-severity anomalies before they escalate into broader incidents.

YARA Rule

rule Armadillov184
{
      meta:
		author="malware-lu"
strings:
		$a0 = { 55 8B EC 6A FF 68 E8 C1 40 00 68 F4 86 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

Here are 5 specific false positive scenarios for the Armadillov184 detection rule, including suggested filters and exclusions tailored for an enterprise environment:

• Scenario: Automated Backup Execution by Veeam

  • Context: The nightly backup job executed by Veeam Backup & Replication launches its agent service (vbrservice.exe) to scan the file system. This process often spawns child processes that match the Armadillo signature due to similar memory allocation patterns or specific API calls used during data staging.
  • Filter/Exclusion: Exclude the parent process vbrservice.exe (Veeam) and its associated service account (DOMAIN\VeeamBackupSvc) from triggering this rule on the backup server segment.

• Scenario: Microsoft Defender Antivirus Real-Time Scanning

  • Context: During peak business hours, Microsoft Defender for Endpoint performs real-time scanning of large document repositories (e.g., OneDrive for Business sync). The MsMpEng.exe process frequently generates file I/O patterns that mimic the Armadillo detection logic, particularly when indexing new user uploads.
  • Filter/Exclusion: Create a rule exclusion based on the executable path C:\Program Files\Microsoft Defender Antivirus\MsMpEng.exe and filter out events where the user context is NT SERVICE\MsMpSvc.

• Scenario: Scheduled PowerShell Script for Compliance Reporting

  • Context: A scheduled Task Scheduler job runs a custom PowerShell script (ComplianceReport.ps1) every Tuesday at 02:00 AM. This script utilizes the .NET framework to query Active Directory and generate CSV reports, triggering the Armadillov184 signature due to its use of specific cryptographic libraries similar to those flagged by the rule.
  • Filter/Exclusion: Exclude events where