You cannot modify termsrv.dll while the Remote Desktop service is actively running. Open as an Administrator. Run the following command to stop the service: net stop termservice Use code with caution. Confirm the prompt if asked. Step 2: Take Ownership of termsrv.dll To replace or modify the file, change its permissions: In the administrative Command Prompt, run: takeown /f C:\Windows\System32\termsrv.dll /a Use code with caution. Next, grant full control to the Administrators group:
: Tools like TermsrvPatcher on GitHub automate this by handling file permissions via TrustedInstaller and restarting the Remote Desktop Service. ⚠️ Risks and Considerations
By default, Windows Server operating systems allow multiple simultaneous Remote Desktop Services (RDS) connections, but they require expensive Client Access Licenses (CALs) and the installation of the Remote Desktop Session Host role. Without these, the operating system limits concurrent remote connections.
Alternatively, use an automated patcher (e.g., Universal Termsrv.dll Patch 1.2 by deepxw). These tools compute the correct offset based on file checksum.
For any scenario that is not a home lab, test environment, or non-production server, the officially supported and compliant path is to properly license and configure the Remote Desktop Services (RDS) role on your Windows Server 2012 R2 machine. This ensures full functionality without legal ambiguity or system instability.
Modifying core authentication libraries like termsrv.dll bypasses Microsoft's cryptographic file integrity checks (SFC). If you download pre-patched DLLs from untrusted sources online, you risk introducing malware or backdoors into your server environment.
Modifying system files carries inherent risks. Before proceeding with any patch, ensure you complete the following steps: