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 APT1-related activity that may evade traditional detection methods.

YARA Rule

rule ccrewDownloader2
{

    meta:
        author = "AlienVault Labs"
        info = "CommentCrew-threat-apt1"
        
    strings:
        $a = "3gZFQOBtY3sifNOl" wide ascii
        $b = "docbWUWsc2gRMv9HN7TFnvnKcrWUUFdAEem9DkqRALoD" wide ascii
        $c = "6QVSOZHQPCMc2A8HXdsfuNZcmUnIqWrOIjrjwOeagILnnScxadKEr1H2MZNwSnaJ" 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 3 string patterns in its detection logic.

• Source Rule

False Positive Guidance

• Scenario: Scheduled system maintenance or patching using PowerShell scripts that include comments with the word “Crew”
  Filter/Exclusion: process.name != "powershell.exe" OR process.args NOT LIKE '%Crew%'

• Scenario: SQL Server Agent job execution that includes comments in T-SQL scripts for documentation purposes
  Filter/Exclusion: process.name != "sqlservr.exe" OR process.args NOT LIKE '%Crew%'

• Scenario: Windows Task Scheduler running a legitimate administrative script that contains a comment with “Crew” for internal reference
  Filter/Exclusion: process.name != "schtasks.exe" OR process.args NOT LIKE '%Crew%'

• Scenario: Ansible playbook execution with inline comments containing “Crew” for team-specific notes
  Filter/Exclusion: process.name != "ansible.exe" OR process.args NOT LIKE '%Crew%'

• Scenario: Log Management Tool (e.g., Splunk or ELK) configured to log comments in event messages that include the term “Crew”
  Filter/Exclusion: process.name != "splunkd.exe" OR process.name != "java.exe" OR process.args NOT LIKE '%Crew%'