Armadillov190c

Hunt Hypothesis

This detection identifies potential malicious activity associated with the Armadillov190c signature through YARA pattern matching on endpoint or file artifacts within the Azure Sentinel environment. Proactive hunting for this behavior is essential to uncover early-stage threats that may not trigger high-severity alerts, allowing the SOC team to investigate and mitigate low-fidelity risks before they escalate into significant incidents.

YARA Rule

rule Armadillov190c
{
      meta:
		author="malware-lu"
strings:
		$a0 = { 55 8B EC 6A FF 68 10 F2 40 00 68 74 9D 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 4 specific false positive scenarios for the Armadillov190c detection rule, including suggested filters and exclusions:

• Scenario: Scheduled Antivirus Definition Updates

  • Context: The enterprise’s endpoint protection suite (e.g., CrowdStrike Falcon, SentinelOne, or Microsoft Defender) runs a daily scheduled task at 02:00 AM to download and install new virus definition signatures. These updates often involve the execution of temporary scripts or binaries that match the behavioral patterns of Armadillov190c, particularly regarding file integrity checks and registry modifications.
  • Filter/Exclusion: Create a time-based exclusion for alerts generated between 01:30 AM and 02:30 AM on weekdays where the process name matches falcon.sys (CrowdStrike) or MsMpEng.exe (Defender). Alternatively, whitelist the specific hash of the update installer executable used by your AV vendor.

• Scenario: Automated Backup Agent Execution

  • Context: The organization utilizes Veeam Backup & Replication or Rubrik agents running on file servers and workstations. During incremental backup windows, these agents scan directories, compress data, and write to the registry, triggering the YARA rule’s logic which detects similar memory footprint patterns and file access sequences associated with Armadillov190c.
  • Filter/Exclusion: Exclude alerts where the parent process is VeeamAgent.exe or rubrik-agent-service. Additionally, apply a filter to ignore events originating from specific backup service accounts (e.g., DOMAIN\BackupSvc) that are known to run these jobs.

• Scenario: Software Deployment via Configuration Management

  • Context: The IT operations team uses **Microsoft Endpoint Configuration Manager (MECM/SCCM