VxEddie1530

Hunt Hypothesis

This detection identifies potential low-severity malware activity matching the specific signature of the VxEddie1530 YARA rule within Azure Sentinel workloads. Proactively hunting for this behavior allows the SOC team to validate false positives and uncover early-stage threats that may evolve into higher-impact incidents if left unmonitored.

YARA Rule

rule VxEddie1530
{
      meta:
		author="malware-lu"
strings:
		$a0 = { E8 [2] 5E 81 EE [2] FC 2E [4] 4D 5A [2] FA 8B E6 81 C4 [2] FB 3B [5] 2E [4] 50 06 56 1E 33 C0 50 1F C4 [3] 2E [4] 2E }

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 VxEddie1530 detection rule in an enterprise environment, along with recommended filters and exclusions:

• Scenario: Microsoft Office Click-to-Run Self-Updates

  • Context: The YARA signature likely detects the OfficeC2RClient.exe or related update components initiating network connections or file modifications that mimic the rule’s threat indicators. This occurs during scheduled maintenance windows (e.g., 03:00 AM) when Office automatically checks for and applies cumulative updates.
  • Filter/Exclusion: Create a process exclusion for C:\Program Files\Microsoft Office\root\Office16\OfficeC2RClient.exe and its child processes. Additionally, filter alerts where the parent process is svchost.exe (specifically the “CoreMessaging” or “UpdateOrchestrator” service) during defined maintenance windows.

• Scenario: Endpoint Protection Agent Scans (CrowdStrike/SentinelOne)

  • Context: During full system scans, EDR agents like CrowdStrike (csagent.exe) or SentinelOne (SentinelAgent.exe) often spawn temporary worker processes that execute scripts or modify registry keys in a manner similar to the detected threat behavior. These activities frequently trigger VxEddie1530 due to high I/O and script execution patterns.
  • Filter/Exclusion: Exclude file paths containing C:\ProgramData\CrowdStrike\ or C:\Program Files\SentinelOne\. Implement a logic filter that suppresses alerts if the process name matches known EDR agent binaries (csagent.exe, SentinelAgent.exe) and the user context is SYSTEM rather than an interactive logged-in user.

• Scenario: Scheduled PowerShell Automation for Patch Management

  • Context: IT operations teams often run