Armadillov300

Hunt Hypothesis

This detection identifies the presence of the Armadillov300 malware signature on endpoints, indicating potential initial access or persistence activities by an adversary utilizing this specific threat family. Proactive hunting for this indicator in Azure Sentinel is essential to uncover early-stage infections that may evade standard high-severity alerts due to their low severity classification, allowing the SOC team to investigate and contain threats before they escalate.

YARA Rule

rule Armadillov300
{
      meta:
		author="malware-lu"
strings:
		$a0 = { 60 E8 [4] 5D 50 51 EB 0F B9 EB 0F B8 EB 07 B9 EB 0F 90 EB 08 FD EB 0B F2 EB F5 EB F6 F2 EB 08 FD EB E9 F3 EB E4 FC E9 59 58 60 33 C9 }

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 Armadillov300 detection rule, including suggested filters and exclusions tailored for an enterprise environment:

• Scenario: Endpoint Protection Policy Updates via CrowdStrike Falcon

  • Context: The CrowdStrike Falcon Sensor performs a scheduled daily update of its cloud-delivered policies. During this process, the sensor’s background service (FalconService.exe) executes a script to download and apply new detection signatures, which mimics the behavior patterns (file creation in temp directories followed by immediate execution) that Armadillov300 is designed to flag as suspicious activity.
  • Suggested Filter/Exclusion: Create an exclusion rule for FalconService.exe when it executes scripts within the %ProgramData%\CrowdStrike\Falcon\ directory. Additionally, exclude process trees where the parent process is FalconService.exe and the file path contains \Falcon\.

• Scenario: Scheduled PowerShell Backup Script Execution

  • Context: A nightly maintenance job runs a custom PowerShell script (Backup-EnterpriseData.ps1) via Task Scheduler to archive logs from the SQL database. The script utilizes System.Management.Automation to generate temporary JSON manifests and invoke external compression tools, triggering the YARA rule’s logic regarding dynamic code generation and file system manipulation which often resembles Armadillo malware behavior.
  • Suggested Filter/Exclusion: Exclude process execution where the parent is svchost.exe (specifically the Schedule service) or powershell.exe, provided the command line contains the specific task name NightlyLogBackup. Alternatively, whitelist the file path C:\Scripts\Ops\Backup-EnterpriseData.ps1 in the YARA rule’s exclusion list.

• Scenario: Microsoft Defender for Endpoint (MDE) Real-Time Scan

  • Context: During