CVE-2025-53149
📋 TL;DR
This vulnerability is a heap-based buffer overflow in the Kernel Streaming WOW Thunk Service Driver (ksthunk.sys) on Windows systems. It allows an authenticated attacker to execute arbitrary code with elevated SYSTEM privileges locally. Any Windows system with the vulnerable driver is affected.
💻 Affected Systems
- Microsoft Windows
📦 What is this software?
Windows 10 1507 by Microsoft
Windows 10 1507 by Microsoft
Windows 10 1607 by Microsoft
Windows 10 1607 by Microsoft
Windows 10 1809 by Microsoft
Windows 10 1809 by Microsoft
Windows 10 21h2 by Microsoft
Windows 10 22h2 by Microsoft
Windows 11 22h2 by Microsoft
Windows 11 23h2 by Microsoft
Windows 11 24h2 by Microsoft
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise with SYSTEM privileges, enabling installation of persistent malware, credential theft, and lateral movement across the network.
Likely Case
Local privilege escalation from a standard user account to SYSTEM, allowing attackers to bypass security controls and maintain persistence.
If Mitigated
Limited impact if proper endpoint protection, application control, and least privilege principles are enforced, though exploitation may still succeed.
🎯 Exploit Status
Exploitation requires local authenticated access. Public proof-of-concept code exists, making weaponization likely.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Apply the latest Windows security updates from Microsoft's May 2025 Patch Tuesday or later
Vendor Advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-53149
Restart Required: Yes
Instructions:
1. Open Windows Update settings. 2. Click 'Check for updates'. 3. Install all available security updates. 4. Restart the system when prompted.
🔧 Temporary Workarounds
Disable ksthunk.sys driver
windowsDisables the vulnerable Kernel Streaming WOW Thunk Service Driver to prevent exploitation
sc config ksthunk start= disabled
sc stop ksthunk
Enable Windows Defender Exploit Guard
windowsConfigure exploit protection to mitigate heap corruption attacks
🧯 If You Can't Patch
- Implement strict application control policies to prevent unauthorized code execution
- Enforce least privilege access and segment networks to limit lateral movement
🔍 How to Verify
Check if Vulnerable:
Check if ksthunk.sys driver version is older than the patched version in May 2025 updatesCheck Version:
systeminfo | findstr /B /C:"OS Name" /C:"OS Version"Verify Fix Applied:
Verify Windows is updated to May 2025 or later security updates and ksthunk.sys driver version is updated📡 Detection & Monitoring
Log Indicators:
- Unusual process creation with SYSTEM privileges from non-admin users
- Suspicious driver loading events
Network Indicators:
- Unusual outbound connections from SYSTEM processes
SIEM Query:
EventID=4688 AND NewProcessName="*" AND SubjectUserName!="SYSTEM" AND TokenElevationType="%%1936"