Chinese Hacktool Set - file Dll_LoadEx.exe

Hunt Hypothesis

This hunt hypothesis targets adversaries leveraging the specific “Dll_LoadEx.exe” artifact from the Chinese Hacktool set to execute DLL loading operations that may indicate early-stage reconnaissance or persistence mechanisms within Windows environments. Proactively hunting for this file in Azure Sentinel is critical because its low-severity classification often allows it to bypass standard alerting thresholds, enabling threat actors to establish a foothold before triggering higher-level detections.

YARA Rule

rule Dll_LoadEx {
	meta:
		description = "Chinese Hacktool Set - file Dll_LoadEx.exe"
		author = "Florian Roth"
		reference = "http://tools.zjqhr.com/"
		date = "2015-06-13"
		hash = "213d9d0afb22fe723ff570cf69ff8cdb33ada150"
	strings:
		$s0 = "[email protected]" fullword wide
		$s1 = "Dll_LoadEx.EXE" fullword wide
		$s3 = "You Already Loaded This DLL ! :(" fullword ascii
		$s10 = "Dll_LoadEx Microsoft " fullword wide
		$s17 = "Can't Load This Dll ! :(" fullword ascii
		$s18 = "WiNrOOt" fullword wide
		$s20 = " Dll_LoadEx(&A)..." fullword wide
	condition:
		uint16(0) == 0x5a4d and filesize < 120KB and 3 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 7 string patterns in its detection logic.

References

False Positive Guidance

Here are 4 specific false positive scenarios for the Chinese Hacktool Set - file Dll_LoadEx.exe detection rule in an enterprise environment, along with recommended filters:

Scenario: Legitimate Software Deployment via SCCM/MECM
- Context: The System Center Configuration Manager (SCCM) or Microsoft Endpoint Configuration Manager deploys a Chinese localization patch or a specific regional application (e.g., WeChat for Business or DingTalk) to endpoints. During the installation phase, the deployment agent (ccmexec.exe) loads Dll_LoadEx.exe as part of the setup routine to register DLLs in the system directory.
- Suggested Filter: Exclude events where the parent process is ccmexec.exe (or ApplicationHost.exe for SCCM) and the file path resides within the standard software distribution folder (e.g., C:\Windows\CCMCache\*).
Scenario: Scheduled Antivirus Definition Updates
- Context: A third-party antivirus solution with strong Chinese market support (such as Kingsoft Internet Security, 360 Total Security, or Qihoo 360) runs a scheduled update job. The scanner engine loads Dll_LoadEx.exe to verify the integrity of newly downloaded signature databases before applying them to the host.
- Suggested Filter: Create an exclusion for file paths located in the vendor’s specific installation directory (e.g., C:\Program Files\Kingsoft\* or C:\Program Files\360TotalSecurity\*) and restrict the rule to trigger only if the parent process is not a known AV service executable (e.g., exclude parent processes named ksafe.exe, 360tray.exe, or avcenter.exe).
Scenario: Enterprise Remote Desktop Session Initialization
- Context: When an administrator initi