AINEXEv230

Hunt Hypothesis

This detection identifies potential malicious executable behavior by leveraging a specific YARA signature (AINEXEv230) to flag known threat patterns within the environment. SOC teams should proactively hunt for this indicator in Azure Sentinel to validate its presence across endpoints and ensure early identification of low-severity threats that may serve as precursors to broader compromise campaigns.

YARA Rule

rule AINEXEv230
{
      meta:
		author="malware-lu"
strings:
		$a0 = { 0E 07 B9 [2] BE [2] 33 FF FC F3 A4 A1 [2] 2D [2] 8E D0 BC [2] 8C D8 }

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 AINEXEv230 detection rule, including suggested filters and exclusions tailored for an enterprise environment:

• Scenario: Microsoft Defender Antivirus Real-Time Scanning of Compressed Archives

  • Context: The YARA rule may flag the MsMpEng.exe process when it extracts or scans large .zip or .7z archives containing executable payloads in user directories (e.g., C:\Users\*\Downloads). This is common during software distribution via Intune or manual downloads.
  • Suggested Filter/Exclusion: Exclude the parent process path C:\Program Files\Microsoft Defender Antivirus\bin\Platform\MsMpEng.exe from triggering this rule when the target file extension matches .zip, .7z, or .rar. Alternatively, add a filter to ignore events where the ProcessName is MsMpEng.exe and the CommandLine contains --scan-type=real-time.

• Scenario: Scheduled PowerShell Script Execution for Patch Management

  • Context: Enterprise patch management tools like SCCM (System Center Configuration Manager) or PDQ Deploy often execute scheduled tasks that invoke powershell.exe to run scripts involving dynamic code generation or module imports. If the script interacts with network resources or modifies registry keys, AINEXEv230 might interpret this as a suspicious execution pattern.
  • Suggested Filter/Exclusion: Create an exclusion for Task Scheduler initiated jobs where the ParentProcessName is svchost.exe (specifically the Schedule service) and the script path contains known patch management directories (e.g., C:\Program Files\Microsoft Configuration Manager\). Additionally, filter out events where the Hash of the executed PowerShell script matches a known whitelist hash.

• **Scenario: CI