After May 2018 security update: RDP "An authentication error occurred" "This could be due to CredSSP encryption oracle remediation".
[Client] i.e. On a Windows 10
When an IT Admin was trying to RDP to a Windows Server, they were getting the following error:
May 2018 'security update' is installed.
[CAUSE]
Starting in the May 2018 Security update we are enforcing the March 2018 CVE-2018-0886.
CredSSP updates for CVE-2018-0886
https://support.microsoft.com/en-us/help/4093492/credssp-updates-for-cve-2018-0866-march-13-2018
My colleagues Paul and Graeme go more in-depth here:
CredSSP, RDP and Raven
https://blogs.technet.microsoft.com/askpfeplat/2018/05/07/credssp-rdp-and-raven/
[Server where RDP to is failing]
May 2018 'security update' is not installed. Matter of fact, this hasn't been patched since May of 2017.
Deleted the gpo in the registry
Restarted WU service
The WSUS/SCCM admin needs to check why some of the Servers are not getting the security updates.
Thanks,
Yong [Somewhere in NorCal for the week]