SpyGate

Hunt Hypothesis

This hypothesis posits that adversaries are utilizing custom malware signatures identified by the SpyGate YARA rule to establish persistent footholds within the environment. The SOC team should proactively hunt for these indicators in Azure Sentinel to validate the efficacy of this low-severity detection and uncover potential stealthy reconnaissance activities before they escalate into critical incidents.

YARA Rule

rule SpyGate : RAT
{
	meta:
		author = " Kevin Breen <[email protected]>"
		date = "2014/04"
		ref = "http://malwareconfig.com/stats/SpyGate"
		maltype = "Remote Access Trojan"
		filetype = "exe"

	strings:
		$split = "abccba"
		$a1 = "abccbaSpyGateRATabccba" //$a = Version 0.2.6
		$a2 = "StubX.pdb" 
		$a3 = "abccbaDanabccb"
		$b1 = "monikerString" nocase //$b = Version 2.0
		$b2 = "virustotal1"
		$b3 = "get_CurrentDomain"
		$c1 = "shutdowncomputer" wide //$c = Version 2.9
		$c2 = "shutdown -r -t 00" wide
		$c3 = "set cdaudio door closed" wide
		$c4 = "FileManagerSplit" wide
		$c5 = "Chating With >> [~Hacker~]" wide

	condition:
		(all of ($a*) and #split > 40) or (all of ($b*) and #split > 10) or (all of ($c*))
}

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 15 string patterns in its detection logic.

• Source Rule

False Positive Guidance

Here are 4 specific false positive scenarios for the SpyGate detection rule in an enterprise environment, along with suggested filters or exclusions:

• Endpoint Protection Real-time Scanning by CrowdStrike Falcon

  • Scenario: The CrowdStrike Falcon sensor (specifically the csagent.exe process) performs deep file integrity scans on sensitive directories. During these scans, it spawns child processes that read and hash large volumes of user data, mimicking the behavior of a spyware agent collecting telemetry or exfiltrating metadata.
  • Filter/Exclusion: Create an exclusion for the csagent.exe process path (C:\Program Files\CrowdStrike\) and its specific child processes when accessing standard user profile directories (e.g., %USERPROFILE%\Documents).

• Microsoft Defender Antivirus Scheduled Cloud Protection Scan

  • Scenario: The daily scheduled “Cloud-Delivered Protection” scan runs via the MsMpEng.exe service. This task involves scanning network shares and local drives, generating temporary log files and uploading hash signatures to the Microsoft cloud, which triggers the SpyGate YARA rule due to high-volume file I/O and outbound connections to known MS endpoints.
  • Filter/Exclusion: Exclude the MsMpEng.exe process when executing under the scheduled task \Microsoft\Windows Defender\MsDefenderScan. Additionally, whitelist outbound traffic from this process to Microsoft Azure storage IPs (e.g., *.blob.core.windows.net).

• Sysmon Configuration Deployment via SCCM/MECM

  • Scenario: During a monthly patch cycle, System Center Configuration Manager (SCCM) deploys updated Sysmon configurations (sysmon.exe) across the fleet. The deployment agent (ccmexec.exe) triggers a configuration reload that involves reading registry hives and writing new XML rule files to C:\Windows\System32\config,