CVE-2025-63685
📋 TL;DR
Quark Cloud Drive v3.23.2 has a DLL hijacking vulnerability where attackers can place malicious DLLs in the application directory that get executed when the program launches. This allows arbitrary code execution with the privileges of the user running the application. All users of this specific version are affected.
💻 Affected Systems
- Quark Cloud Drive
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise via arbitrary code execution with user privileges, potentially leading to privilege escalation, data theft, or ransomware deployment.
Likely Case
Local privilege escalation leading to malware installation, credential theft, or lateral movement within the network.
If Mitigated
Limited impact if application runs with minimal privileges and proper endpoint protection blocks malicious DLL execution.
🎯 Exploit Status
Exploitation requires local access to place malicious DLL. The GitHub reference shows proof-of-concept details.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Unknown
Vendor Advisory: Unknown
Restart Required: No
Instructions:
1. Monitor vendor website for security updates
2. Apply patch when available
3. Verify DLL loading uses secure paths
🔧 Temporary Workarounds
Restrict application directory permissions
windowsPrevent unauthorized users from writing DLLs to the Quark Cloud Drive installation directory
icacls "C:\Program Files\Quark Cloud Drive\*" /deny Users:(W)
Use application whitelisting
windowsConfigure Windows Defender Application Control or similar to only allow signed DLLs
🧯 If You Can't Patch
- Run application with minimal user privileges (not as administrator)
- Monitor for suspicious DLL creation in application directories using file integrity monitoring
🔍 How to Verify
Check if Vulnerable:
Check if Quark Cloud Drive v3.23.2 is installed and if regsvr32.exe loads DLLs from insecure pathsCheck Version:
Check application properties or registry: HKEY_LOCAL_MACHINE\SOFTWARE\Quark\Cloud DriveVerify Fix Applied:
Verify updated version or test if malicious DLL placed in application directory fails to execute📡 Detection & Monitoring
Log Indicators:
- Process creation of regsvr32.exe from Quark Cloud Drive directory
- DLL loading from unusual locations
Network Indicators:
- Unexpected outbound connections after application launch
SIEM Query:
Process Creation where (Image contains 'regsvr32.exe' AND ParentImage contains 'Quark') OR (DllLoaded contains malicious.dll)