What is error code 0x12?
Failure code 0x12 very specifically means “Clients credentials have been revoked”, which means that this error has happened once the account has been disabled, expired, or locked out.
What is pre-Authentication failed?
This problem can occur when a domain controller doesn’t have a certificate installed for smart card authentication (for example, with a “Domain Controller” or “Domain Controller Authentication” template), the user’s password has expired, or the wrong password was provided.
What is eventcode 4771?
4771: Kerberos pre-authentication failed. This event is logged on domain controllers only and only failure instances of this event are logged. At the beginning of the day when a user sits down at his or her workstation and enters his domain username and password, the workstation contacts a local DC and requests a TGT.
Do you not need Kerberos Preauthentication?
When you do not enforce pre-authentication, a malicious attacker can directly send a dummy request for authentication. The KDC will return an encrypted TGT and the attacker can brute force it offline.
How can I tell what is using NTLM authentication?
To find applications that use NTLMv1, enable Logon Success Auditing on the domain controller, and then look for Success auditing Event 4624, which contains information about the version of NTLM.
What is service name Krbtgt?
Kerberos Service Account (KRBTGT) in Microsoft Windows is the Service Account and a Privileged Identity for the Key Distribution Center (KDC) service that is used to apply Digital Signatures and Encryption every authentication Ticket Granting Ticket (TGT).
How do I fix Kerberos authentication?
Resolution. To resolve this problem, update the registry on each computer that participates in the Kerberos authentication process, including the client computers. We recommend that you update all of your Windows-based systems, especially if your users have to log on across multiple domains or forests.
How do I know if my Kerberos authentication is working?
Assuming you’re auditing logon events, check your security event log and look for 540 events. They will tell you whether a specific authentication was done with Kerberos or NTLM.