EYouDiDaiYueHeiFengGao

Hunt Hypothesis

This detection identifies potential file-based threats matching the specific signature of the “EYouDiDaiYueHeiFengGao” YARA rule, which may indicate early-stage adversary activity involving known malware or suspicious artifacts within the environment. Although currently flagged with low severity, proactively hunting for this pattern in Azure Sentinel allows the SOC team to validate false positives and uncover subtle indicators of compromise before they escalate into critical incidents.

YARA Rule

rule EYouDiDaiYueHeiFengGao
{
      meta:
		author="malware-lu"
strings:
		$a0 = { 55 8B EC B8 [4] E8 [4] 53 56 57 0F 31 8B D8 0F 31 8B D0 2B D3 C1 EA 10 B8 [4] 0F 6E C0 B8 [4] 0F 6E C8 0F F5 C1 0F 7E C0 0F 77 03 C2 [5] FF E0 }

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 EYouDiDaiYueHeiFengGao detection rule, tailored for a legitimate enterprise environment:

• Scenario: An automated backup job utilizing Veeam Backup & Replication initiates a full image capture of a critical SQL Server database. The YARA rule flags the vbr.exe process spawning multiple child processes to compress and encrypt data blocks as suspicious behavior due to high I/O and memory allocation patterns matching the heuristic logic.

  • Suggested Filter: Exclude alerts where the parent process is vbr.exe (Veeam) running on the scheduled backup window (e.g., 02:00–04:00 UTC) and the file path matches the Veeam installation directory (C:\Program Files\Veeam\Backup and Replication).

• Scenario: The IT Operations team executes a bulk patch deployment using Microsoft Endpoint Configuration Manager (SCCM) or Intune. During the deployment, the ccmsetup.exe agent performs a series of rapid file modifications and registry updates across 50+ workstations simultaneously, triggering the rule due to the high volume of concurrent process creation.

  • Suggested Filter: Create an exclusion for processes originating from the SCCM client directory (C:\Program Files (x86)\Microsoft Configuration Manager\) where the command line contains keywords like install, patch, or deployment.

• Scenario: A scheduled Antivirus engine update (e.g., CrowdStrike Falcon or Symantec Endpoint Protection) runs its daily signature refresh. The rule detects the antivirus service (FalconService.exe or rtvscan64.exe) scanning a large directory of user documents, which mimics the file traversal and network connection patterns defined in the YARA logic.

  • **Suggested