Backdoor APT Mongal

Hunt Hypothesis

The Backdoor APT Mongal detection rule identifies potential adversary persistence by leveraging a known malicious payload associated with the APT group, indicating possible long-term access to the network. SOC teams should proactively hunt for this behavior in Azure Sentinel to detect and mitigate early-stage compromise by an advanced persistent threat actor.

YARA Rule

rule Backdoor_APT_Mongal
{

    meta:
        author = "@patrickrolsen"
        maltype = "Backdoor.APT.Mongall"
        version = "0.1"
        reference = "fd69a799e21ccb308531ce6056944842" 
        date = "01/04/2014"
    
    strings:
        $author  = "author user"
        $title   = "title Vjkygdjdtyuj" nocase
        $comp    = "company ooo"
        $cretime = "creatim\\yr2012\\mo4\\dy19\\hr15\\min10"
        $passwd  = "password 00000000"
    
    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 5 string patterns in its detection logic.

References

• fd69a799e21ccb308531ce6056944842
• Source Rule

False Positive Guidance

• Scenario: Scheduled System Maintenance Task
  Description: A legitimate scheduled task using schtasks.exe is configured to run a maintenance script that inadvertently matches the YARA signature due to similar string patterns.
  Filter/Exclusion: Exclude processes initiated by schtasks.exe with a known command line or parent process from the System or Task Scheduler service.

• Scenario: Admin Using PowerShell for Remote Management
  Description: An administrator uses PowerShell (powershell.exe) to remotely manage a server, and the script or command used contains strings that match the YARA rule for Backdoor_APT_Mongal.
  Filter/Exclusion: Exclude processes where the parent process is mstsc.exe (Remote Desktop) or winrm.exe, or where the command line includes known admin tools like Invoke-Command or Enter-PSSession.

• Scenario: Legitimate Software Installation
  Description: A legitimate software package (e.g., 7-Zip, WinRAR, or Chocolatey) is being installed, and its installation script or binary contains strings that match the YARA signature.
  Filter/Exclusion: Exclude processes initiated by msiexec.exe, choco.exe, or setup.exe from trusted software vendors, or use a whitelist of known safe files.

• Scenario: Database Backup Job
  Description: A database backup job using sqlcmd.exe or mysqldump.exe is running, and the command line or output contains strings that trigger the YARA rule.
  Filter/Exclusion: Exclude processes where the command line includes known backup commands or where the parent process is a database service (e.g., sqlservr.exe, mysqld.exe).

• Scenario: User-Initiated File Compression
  Description: A user is using `7-Zip