If you prefer manual modification, you can use a HEX editor (like HxD) to change specific byte sequences.
| Drawback | Description | |----------|-------------| | | Using the patch for any purpose beyond administrative access violates Microsoft licensing terms | | Security Exposure | Systems using patches often delay security updates, leaving known vulnerabilities unpatched | | Operational Instability | Windows updates frequently break patches; restoring functionality may require manual intervention during outages | | Missing Official Support | Microsoft will refuse support for any system with modified termsrv.dll |
Windows Cumulative Updates frequently replace or update system files, including termsrv.dll . Whenever Microsoft patches an RDP vulnerability or updates the service, your patched file will be overwritten by a standard version. You will have to re-patch the file after almost every major update cycle. 3. System Instability and Security Vulnerabilities
How to Patch termsrv.dll for Multiple RDP Sessions on Windows Server 2016 termsrv.dll patch windows server 2016
Because Windows Server 2016 updates can change the exact build number, the hex pattern might vary slightly depending on your update level. Copy C:\Windows\System32\termsrv.dll to your Desktop. Open the desktop copy in your Hex Editor.
“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.”
The system can support up to 15 concurrent RDP sessions, though actual limits depend on hardware capabilities (CPU, memory, network bandwidth) and OS version. If you prefer manual modification, you can use
Before proceeding, it is vital to understand the ramifications of modifying core system files:
If patching the DLL feels too risky or difficult to maintain (as Windows Update will often overwrite the patched file), consider using the open-source . This acts as a middleman, allowing multiple sessions without modifying the termsrv.dll file directly. It is generally safer and easier to uninstall if issues arise.
Run netstat -an | findstr ":3389" and test concurrent logins. You will have to re-patch the file after
Open C:\Windows\System32\termsrv.dll using a hex editor (such as HxD). Search for the specific byte pattern unique to Windows Server 2016 and replace it.
Before proceeding with patching termsrv.dll, ensure that: