CommentCrew-threat-apt1

Hunt Hypothesis

The CommentCrew-threat-apt1 rule detects potential adversary behavior involving suspicious comment creation or modification in cloud storage, which may indicate reconnaissance or initial compromise. SOC teams should proactively hunt for this behavior in Azure Sentinel to identify early-stage threats and prevent lateral movement or data exfiltration.

YARA Rule

rule APT1_payloads
{

    meta:
        author = "AlienVault Labs"
        info = "CommentCrew-threat-apt1"

    strings:
        $pay1 = "rusinfo.exe" wide ascii
        $pay2 = "cmd.exe" wide ascii
        $pay3 = "AdobeUpdater.exe" wide ascii
        $pay4 = "buildout.exe" wide ascii
        $pay5 = "DefWatch.exe" wide ascii
        $pay6 = "d.exe" wide ascii
        $pay7 = "em.exe" wide ascii
        $pay8 = "IMSCMig.exe" wide ascii
        $pay9 = "localfile.exe" wide ascii
        $pay10 = "md.exe" wide ascii
        $pay11 = "mdm.exe" wide ascii
        $pay12 = "mimikatz.exe" wide ascii
        $pay13 = "msdev.exe" wide ascii
        $pay14 = "ntoskrnl.exe" wide ascii
        $pay15 = "p.exe" wide ascii
        $pay16 = "otepad.exe" wide ascii
        $pay17 = "reg.exe" wide ascii
        $pay18 = "regsvr.exe" wide ascii
        $pay19 = "runinfo.exe" wide ascii
        $pay20 = "AdobeUpdate.exe" wide ascii
        $pay21 = "inetinfo.exe" wide ascii
        $pay22 = "svehost.exe" wide ascii
        $pay23 = "update.exe" wide ascii
        $pay24 = "NTLMHash.exe" wide ascii
        $pay25 = "wpnpinst.exe" wide ascii
        $pay26 = "WSDbg.exe" wide ascii
        $pay27 = "xcmd.exe" wide ascii
        $pay28 = "adobeup.exe" wide ascii
        $pay29 = "0830.bin" wide ascii
        $pay30 = "1001.bin" wide ascii
        $pay31 = "a.bin" wide ascii
        $pay32 = "ISUN32.EXE" wide ascii
        $pay33 = "AcroRD32.EXE" wide ascii
        $pay34 = "INETINFO.EXE" wide ascii

    condition:
        1 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 34 string patterns in its detection logic.

• Source Rule

False Positive Guidance

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

• Scenario: Admin performing a database backup using SQL Server Agent Job
  Filter/Exclusion: process.parent_process_name:"sqlservr.exe" or process.name:"sqlagent.exe"

• Scenario: IT team using PowerShell to generate reports with Out-GridView
  Filter/Exclusion: process.name:"powershell.exe" AND process.command_line:"Out-GridView"

• Scenario: User running a legitimate script for log analysis using Python and pandas
  Filter/Exclusion: process.name:"python.exe" AND process.command_line:"pandas" OR process.user:"legitimate_user"

• Scenario: System running a legitimate scheduled task with Windows Task Scheduler to clean temporary files
  Filter/Exclusion: process.name:"taskhost.exe" AND process.command_line:"*clean*temp*"