CommentCrew-threat-apt1

Hunt Hypothesis

CommentCrew-threat-apt1 detects potential adversary behavior involving suspicious comment-based PowerShell scripts that may be used for initial access or command and control. SOC teams should proactively hunt for this behavior in Azure Sentinel to identify and mitigate early-stage compromise attempts by advanced persistent threats.

YARA Rule

rule ccrewQAZ
{

    meta:
        author = "AlienVault Labs"
        info = "CommentCrew-threat-apt1"
        
    strings:
        $a = "!QAZ@WSX" wide ascii

  condition:
        $a
}

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

• Scenario: Scheduled System Maintenance Job
  Description: A legitimate scheduled task runs a script that includes a comment referencing “Crew” as part of a maintenance log.
  Filter/Exclusion: Exclude events where the process is schtasks.exe or the script path contains SystemMaintenance or ScheduledTasks.

• Scenario: Admin Task for User Management
  Description: An administrator uses PowerShell to create a user with a comment field containing “Crew” as part of a user naming convention.
  Filter/Exclusion: Exclude events where the process is powershell.exe and the command includes New-LocalUser or Add-LocalGroupMember.

• Scenario: Log File Parsing Tool
  Description: A log parsing tool (e.g., logparser.exe) processes logs and includes a comment field with “Crew” as part of a log entry.
  Filter/Exclusion: Exclude events where the process is logparser.exe or the log source is a known internal log server (e.g., logserver01).

• Scenario: Backup Script with Comment
  Description: A backup script (e.g., backup_script.bat) includes a comment line with “Crew” to indicate the script’s purpose.
  Filter/Exclusion: Exclude events where the process is cmd.exe and the script path contains backup or backup_script.

• Scenario: Internal Documentation Tool
  Description: An internal documentation tool (e.g., docgen.exe) generates a document with a comment field that includes “Crew” as part of a team name.
  Filter/Exclusion: Exclude events where the process is docgen.exe or the document path contains internal_docs or team_notes.