APT NGO wuaclt

Hunt Hypothesis

The hypothesis is that the detection identifies potential command and control activity associated with the APT NGO group, leveraging the wuaclt tool for covert communication. SOC teams should proactively hunt for this behavior in Azure Sentinel to identify early-stage adversarial activity and prevent further compromise of network assets.

YARA Rule

rule APT_NGO_wuaclt
{
   
   meta:
    author = "AlienVault Labs"
  
  strings:
    $a = "%%APPDATA%%\\Microsoft\\wuauclt\\wuauclt.dat"
    $b = "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1)"
    $c = "/news/show.asp?id%d=%d"
    
    $d = "%%APPDATA%%\\Microsoft\\wuauclt\\"
    $e = "0l23kj@nboxu"
    
    $f = "%%s.asp?id=%%d&Sid=%%d"
    $g = "User-Agent: Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SP Q%%d)"
    $h = "Cookies: UseID=KGIOODAOOK%%s"

  condition:
    ($a and $b and $c) or ($d and $e) or ($f and $g and $h)
}

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 8 string patterns in its detection logic.

• Source Rule

False Positive Guidance

• Scenario: Scheduled System Maintenance Task
  Description: A legitimate system maintenance task using wuauclt.exe (Windows Update Assistant) is executed as part of a scheduled job to ensure system updates are applied.
  Filter/Exclusion: Check for Process.ParentProcessName == "schtasks.exe" or Process.CommandLine.Contains("schtasks")

• Scenario: Windows Update Deployment via Group Policy
  Description: The wuauclt.exe process is triggered by Group Policy to deploy updates across the enterprise, which is a normal part of endpoint management.
  Filter/Exclusion: Filter by Process.ParentProcessName == "services.exe" or Process.CommandLine.Contains("GroupPolicy")

• Scenario: Manual Windows Update Trigger by Admin
  Description: An administrator manually initiates a Windows Update via the command line or GUI, which invokes wuauclt.exe.
  Filter/Exclusion: Check for Process.CommandLine.Contains("wuauclt.exe") or Process.User == "Administrator"

• Scenario: Third-Party Patch Management Tool Integration
  Description: A third-party patch management tool (e.g., Microsoft Endpoint Manager, SCCM, or Altiris) uses wuauclt.exe as part of its update process.
  Filter/Exclusion: Filter by Process.CommandLine.Contains("Microsoft Endpoint Manager") or Process.CommandLine.Contains("SCCM")

• Scenario: False Positive from Malware Analysis Environment
  Description: During malware analysis, a sandbox or analysis tool runs wuauclt.exe as part of its testing environment, leading to a false positive.
  Filter/Exclusion: Check for Process.MachineName.Contains("sandbox") or Process.MachineName.Contains("analysis")