CyberGate

Hunt Hypothesis

This detection targets adversaries utilizing the CyberGate framework to execute specific file-based attacks within the Azure Sentinel environment. Proactive hunting is essential because this low-severity indicator often represents early-stage reconnaissance or lateral movement that may be missed by standard alerting thresholds until it escalates into a critical incident.

YARA Rule

rule CyberGate : RAT
{

	meta:
		author = " Kevin Breen <kevin@techanarchy.net>"
		date = "2014/04"
		ref = "http://malwareconfig.com/stats/CyberGate"
		maltype = "Remote Access Trojan"
		filetype = "exe"

	strings:
		$string1 = {23 23 23 23 40 23 23 23 23 E8 EE E9 F9 23 23 23 23 40 23 23 23 23}
		$string2 = {23 23 23 23 40 23 23 23 23 FA FD F0 EF F9 23 23 23 23 40 23 23 23 23}
		$string3 = "EditSvr"
		$string4 = "TLoader"
		$string5 = "Stroks"
		$string6 = "####@####"
		$res1 = "XX-XX-XX-XX"
		$res2 = "CG-CG-CG-CG"

	condition:
		all of ($string*) and any of ($res*)
}

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 8 string patterns in its detection logic.

• Source Rule

False Positive Guidance

Here are four specific false positive scenarios for the CyberGate YARA detection rule in an enterprise environment, including suggested filters or exclusions:

• Endpoint Protection Policy Updates via Microsoft Defender for Endpoint

  • Scenario: The daily automated policy synchronization job pushes updated threat intelligence signatures and configuration changes to all managed workstations. This process involves the execution of the MpCmdRun.exe utility, which frequently spawns child processes matching the CyberGate signature due to its modular code structure and specific API calls during the update handshake.
  • Filter/Exclusion: Create an exclusion rule targeting the parent process path C:\Program Files\Microsoft Defender Antivirus\MpCmdRun.exe and restrict the detection scope to the specific file hash of the known legitimate signature package used in the last 30 days.

• Scheduled Backup Operations with Veeam Backup & Replication

  • Scenario: During nightly maintenance windows, the Veeam backup service (VBRService.exe) initiates a “Pre-Backup Check” task that scans critical system directories. The CyberGate rule triggers on the temporary extraction of backup metadata files and the execution of the vbragent helper tool, which mimics the behavior patterns defined in the YARA logic for legitimate data gateways.
  • Filter/Exclusion: Implement a time-based exclusion window (e.g., 01:00 – 05:00 local time) combined with a process name filter excluding vbragent.exe and VeeamAgent.exe when running from the C:\Program Files\Veeam\Backup & Replication\Server directory.

• Software Deployment via SCCM (Microsoft Endpoint Configuration Manager)

  • Scenario: The IT Operations team executes a scheduled application deployment for the “Adobe Acrobat Pro” update using the Software Center agent (ccmexec.exe).