If you tried to RDP to your server and you encountered the following message which you will not be able to login to the server.
“An authentication error has occurred.
The function requested is not supported.
This could be due to CredSSP encryption oracle remediation.
For more information, see https://go.microsoft.com/fwlink/?linkid=866660”
This message is shown due to your local machine, most likely has the latest Windows update installed for CredSSP updates, CVE-2018-0886 but your server does not have the relevant update install.
For more information about the CredSSP update, kindly visit this url > https://support.microsoft.com/en-us/help/4093492/credssp-updates-for-cve-2018-0886-march-13-2018
You will need to install the Windows update for CredSSP so that the message will not appear however to do that, you will need to use the current workaround on your local machine so that you can gain access to the server:
- Press the Windows icon on the bottom left of the task bar.
- Type "policy editor" (without the quotes) and under the "Best match" section, select "Edit group policy".
- Click on "Computer Configuration" > "Administrative Templates" > "System" > "Credentials Delegation" and double click on "Encryption Oracle Remediation".
- Click on "Enabled" checkbox and under "Protection level", click on the drop down menu and select "Vulnerable" and select "OK".
- Attempt to RDP to the server and you should be able to do so without encountering the message.
- Then proceed to install Windows update for CredSSP in the server.
- Once you have installed the update for CredSSP in the server, do step 1 to 4 again. However instead of choosing "Vulnerable" at step 4, choose "Not configured" which will set it back to default.