Check status with RDPCheck.exe (bundled). If it shows "Listening on port 3389" and "Supported" with unlimited connections, you succeeded.
takeown /f C:\Windows\System32\termsrv.dll /a icacls C:\Windows\System32\termsrv.dll /grant Administrators:F Use code with caution. Step 2: Stop the Remote Desktop Service
Replacing or hex-editing core system DLLs can cause system crashes or boot loops if done incorrectly.
Open HxD as an Administrator and open C:\Windows\System32\termsrv.dll . termsrv.dll patch windows server 2016
You must grant your user account "Full Control" permissions over the file to replace it.
Remember: With great power comes great responsibility—and the risk of a non-compliant, unsupported server. Patch wisely.
The "interesting feature" associated with patching termsrv.dll Check status with RDPCheck
“Adversaries may modify and/or replace the Terminal Services DLL to enable persistent access to victimized hosts... For example, an adversary may enable features such as concurrent Remote Desktop Protocol sessions by either patching the termsrv.dll file or modifying the ServiceDll value to point to a DLL that provides increased RDP functionality.”
If you only need to allow more than one session per user (rather than bypassing the total connection limit), you can often do this via Group Policy without patching the DLL: Open gpedit.msc .
Modifying system binaries can expose the server to vulnerabilities. Step 2: Stop the Remote Desktop Service Replacing
One of the most accessible solutions is the TermsrvPatcher.ps1 PowerShell script developed by Lukasz Bodziony. This script automates the entire patching process, making it suitable for administrators who prefer hands-off automation.
If manual hex editing feels too risky or tedious, many administrators use open-source projects like the .
You cannot modify termsrv.dll while the Remote Desktop service is actively running. Press Windows Key + R , type services.msc , and press . Locate Remote Desktop Services in the list. Right-click it and select Stop . Alternatively, open an elevated PowerShell window and run: powershell Stop-Service -Name TermService -Force Use code with caution. Step 2: Take Ownership of termsrv.dll
This isn‘t just theoretical—ransomware gangs have actively exploited termsrv.dll patching. The Crypto24 ransomware group was documented patching termsrv.dll to enable multiple simultaneous RDP connections, allowing them to maintain access and deploy ransomware across more systems simultaneously. By bypassing session limits, attackers can log in from multiple compromised credentials concurrently, making detection and remediation significantly more difficult.