Armadillov190a

Hunt Hypothesis

This detection identifies the presence of the Armadillov190a malware variant by leveraging a specific YARA signature to capture its unique code patterns within the environment. Proactive hunting for this indicator in Azure Sentinel is essential to uncover potential early-stage infections that may evade standard heuristic controls, allowing analysts to isolate affected assets before lateral movement occurs.

YARA Rule

rule Armadillov190a
{
      meta:
		author="malware-lu"
strings:
		$a0 = { 55 8B EC 64 FF 68 10 F2 40 00 68 14 9B 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 Armadillov190a detection rule, including tailored filters and exclusions:

• Scenario: Microsoft Defender Antivirus Scheduled Scan

  • Context: The daily automated scan performed by Microsoft Defender Antivirus often triggers this rule when it enumerates or updates its signature database, mimicking the behavior of the Armadillov190a payload.
  • Filter/Exclusion: Exclude processes where ProcessName matches MsMpEng.exe and CommandLine contains keywords like “Scan” or “Update”. Alternatively, filter out events occurring during the defined maintenance window (e.g., 02:00–04:00) for this specific process.

• Scenario: SCCM/ConfigMgr Software Deployment

  • Context: During a scheduled software deployment cycle, System Center Configuration Manager (SCCM) utilizes the ccmsetup.exe or WUAHandler.exe to push updates and install patches, which generates file system activity indistinguishable from the rule’s detection logic.
  • Filter/Exclusion: Create an exclusion for parent processes named ccmexec.exe or WUAHandler.exe. Additionally, filter out events where the UserAccount is a service account (e.g., DOMAIN\SCCM-Deploy-Svc) rather than an interactive user.

• Scenario: Backup Agent Data Indexing

  • Context: Enterprise backup solutions like Veeam Backup & Replication or Acronis Cyber Protect run background indexing jobs that read and hash large volumes of files, triggering the YARA signature due to similar I/O patterns.
  • Filter/Exclusion: Exclude processes matching VeeamAgent.exe, AcronisCyberProtect.exe, or Commvault.cmd. A specific filter could be