CommentCrew-threat-apt1

Hunt Hypothesis

CommentCrew-threat-apt1 detects potential adversary behavior involving the use of comment-based PowerShell scripts to execute malicious commands, which may indicate a low-severity but persistent threat actor leveraging obfuscation techniques. SOC teams should proactively hunt for this behavior in Azure Sentinel to identify and mitigate early-stage compromise attempts that may evade traditional detection methods.

YARA Rule

rule APT1_WEBC2_TOCK
{

    meta:
        author = "AlienVault Labs"
        info = "CommentCrew-threat-apt1"
        
    strings:
        $1 = "InprocServer32" wide ascii
        $2 = "HKEY_PERFORMANCE_DATA" wide ascii
        $3 = "<!---[<if IE 5>]id=" wide ascii

    condition:
        all of them
}

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 3 string patterns in its detection logic.

• Source Rule

False Positive Guidance

• Scenario: Scheduled system maintenance using Task Scheduler
  Filter/Exclusion: process.parent_process_name != "schtasks.exe" or process.name != "schtasks.exe"

• Scenario: Admin performing a disk cleanup using Disk Cleanup Tool
  Filter/Exclusion: process.name != "cleanmgr.exe" or process.parent_process_name != "explorer.exe"

• Scenario: Database backup job executed via SQL Server Agent Job
  Filter/Exclusion: process.name != "sqlservr.exe" or process.parent_process_name != "sqlagent.exe"

• Scenario: User running a legitimate script for log rotation using PowerShell
  Filter/Exclusion: process.name != "powershell.exe" or process.parent_process_name != "cmd.exe"

• Scenario: IT staff using Windows Event Viewer to review logs
  Filter/Exclusion: process.name != "eventvwr.exe" or process.parent_process_name != "explorer.exe"