EmbedPEv124cyclotron

Hunt Hypothesis

This detection identifies potential adversary activity involving embedded PE executables that match specific Cyclone signatures, which may indicate early-stage file-based attacks or supply chain compromises. SOC teams should proactively hunt for these indicators in Azure Sentinel to uncover stealthy threats that might evade standard signature-based defenses and prevent lateral movement before escalation.

YARA Rule

rule EmbedPEv124cyclotron
{
      meta:
		author="malware-lu"
strings:
		$a0 = { 83 EC 50 60 68 [4] E8 CB FF 00 00 }

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 EmbedPEv124cyclotron detection rule, including suggested filters and exclusions:

• Scenario: Microsoft Office Macro Execution via OneDrive Sync

  • Context: Users frequently open Excel or Word documents containing embedded macros stored in OneDrive. The Cyclone engine often flags the temporary extraction of these Office files (.docx, .xlsx) as suspicious PE embedding behavior when the OneDrive sync client processes them locally.
  • Filter/Exclusion: Add a path exclusion for the OneDrive cache directory and Office temp folders: C:\Users\*\AppData\Local\Microsoft\OneDrive\ AND C:\Program Files\Microsoft Office\root\Office16\. Additionally, exclude processes where the parent process is FileAccess.exe (OneDrive) or excel.exe/winword.exe.

• Scenario: Scheduled Antivirus Definition Updates

  • Context: Enterprise environments often run scheduled tasks to update antivirus definitions. Tools like CrowdStrike Falcon, Symantec Endpoint Protection, or Microsoft Defender for Endpoint frequently inject new definition modules into memory, which the rule interprets as a new PE embedding event.
  • Filter/Exclusion: Create an exclusion based on specific service names and scheduled task triggers. Exclude events where the process name matches CcsSvc.exe (CrowdStrike), Symantec Endpoint Protection, or MsMpEng.exe running under the “System” account during off-hours (e.g., 01:00–05:00).

• Scenario: Deployment of Group Policy Preferences via SCCM

  • Context: When Microsoft System Center Configuration Manager (SCCM) pushes new application configurations or software updates, it often utilizes embedded scripts within PE containers to configure user environments. The