gtalocker

Hunt Hypothesis

The detection rule identifies potential GTALocker ransomware activity by matching known malicious patterns associated with the malware. SOC teams should proactively hunt for this behavior in Azure Sentinel to detect early-stage ransomware campaigns before significant data encryption and operational disruption occur.

YARA Rule

rule gtalocker: amtrckr
{
	meta:
		family = "gtalocker"

	condition:
		androguard.url(/niktoegoneyznaet0kol\.pw/)
}

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
• Source Rule

False Positive Guidance

• Scenario: Scheduled System Maintenance Task
  Description: A legitimate system maintenance task, such as a Windows Task Scheduler job that runs a script or tool like PowerShell or PsExec, may trigger the gtalocker YARA rule due to similar string patterns.
  Filter/Exclusion: Exclude processes associated with scheduled tasks by checking the TaskName or CommandLine for known maintenance scripts or tools.

• Scenario: Antivirus or Endpoint Protection Scan
  Description: Antivirus tools like Kaspersky, Bitdefender, or Malwarebytes may trigger the gtalocker rule during a full system scan due to heuristic analysis or signature overlap.
  Filter/Exclusion: Exclude processes with known antivirus tool names or parent processes from trusted security vendors.

• Scenario: System File Integrity Check (SFIC)
  Description: Tools like Sysinternals Process Explorer or Windows File Integrity Check (FIC) may trigger the rule when scanning system files for changes.
  Filter/Exclusion: Exclude processes related to file integrity checks by checking the ImageFileName or CommandLine for known tools like Process Explorer or fsutil.

• Scenario: Administrative Script Execution
  Description: A script written by an admin using PowerShell or Batch to perform routine tasks (e.g., log cleanup, registry edits) may contain strings that match the gtalocker YARA rule.
  Filter/Exclusion: Exclude processes with ImageFileName set to powershell.exe or cmd.exe and filter by user context (e.g., User field = “Administrator” or “Domain Admin”).

• Scenario: Log Collection or Monitoring Tool
  Description: Tools like Splunk, ELK Stack, or Logstash may trigger the rule