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 EclipseSunCloudRAT
{

    meta:
        author = "AlienVault Labs"
        info = "CommentCrew-threat-apt1"
        
    strings:
        $a = "Eclipse_A" wide ascii
        $b = "\\PJTS\\" wide ascii
        $c = "Eclipse_Client_B.pdb" wide ascii
        $d = "XiaoME" wide ascii
        $e = "SunCloud-Code" wide ascii
        $f = "/uc_server/data/forum.asp" wide ascii

    condition:
        any 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 6 string patterns in its detection logic.

• Source Rule

False Positive Guidance

• Scenario: Scheduled system maintenance using task scheduler
  Filter/Exclusion: process.parent_process_name:"Task Scheduler" or process.command_line:"schtasks.exe"

• Scenario: Database backup job using SQL Server Agent
  Filter/Exclusion: process.parent_process_name:"sqlservr.exe" or process.command_line:"sqlagent.exe"

• Scenario: Admin performing a log cleanup using Log Parser
  Filter/Exclusion: process.parent_process_name:"logparser.exe" or process.command_line:"logparser.exe"

• Scenario: User running a legitimate script for system monitoring using PowerShell
  Filter/Exclusion: process.parent_process_name:"WindowsPowerShell.exe" or process.command_line:"powershell.exe -Command"

• Scenario: IT team deploying a patch using Windows Update
  Filter/Exclusion: process.parent_process_name:"wuauclt.exe" or process.command_line:"wuauclt.exe"