How to Fix CredSSP Encryption Oracle Remediation Errors in RDP

When attempting to connect to a machine using Remote Desktop Protocol (RDP), you may encounter the following error due to CredSSP encryption issues:

An authentication error has occurred. The function requested is not supported,  This error is typically caused when the server you are trying to connect to is not patched up to date, while your local machine is. To resolve this issue temporarily, you can modify your registry settings to allow the connection:

Run the following command as an administrator:

REG ADD "HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System\CredSSP\Parameters" /v AllowEncryptionOracle /t REG_DWORD /d 2

This registry entry is a temporary workaround. Once you have patched your server, remove this setting with the following command:

REG Delete "HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System\CredSSP\Parameters" /v AllowEncryptionOracle

You can also manually modify the registry to achieve the same result:

1. Open Regedit.
2. Navigate to the following registry key, or create it if it does not exist:

   HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System\CredSSP\Parameters

3. Create a new DWORD value called AllowEncryptionOracle.
4. Set the new registry entry to have a value of 2:

Once you have set the value of AllowEncryptionOracle to 2, you should be able to connect to the server that was previously inaccessible.

In conclusion, this workaround allows you to bypass the CredSSP encryption error temporarily, enabling you to connect to your RDP server. However, it is crucial to patch the server as soon as possible to ensure security and remove the temporary registry modification.