Microsoft has released optional out-of-band (OOB) updates to fix a known issue triggering Kerberos sign-in failures and other authentication problems on enterprise Windows domain controllers after installing cumulative updates released during November’s Patch Tuesday. This issue was previously covered in ThreatWatch.
The company acknowledged and started investigating on Monday when it also said that the known issue could affect any Kerberos authentication scenario within affected enterprise environments. While Microsoft has also started enforcing security hardening for Kerberos and Netlogon beginning with the November 2022 Patch Tuesday, it said that these auth problems are not an expected result. “After installing updates released on November 8, 2022, or later on Windows Servers with the Domain Controller role, you might have issues with Kerberos authentication,” Microsoft explained. “When this issue is encountered, you might receive a Microsoft-Windows-Kerberos-Key-Distribution-Center Event ID 14 error event in the System Log of Event Log on your Domain Controller with the text below.”
The list of impacted Kerberos auth scenarios includes but is not limited to the following:
- Domain user sign-in might fail. This also might affect Active Directory Federation Services (AD FS) authentication.
- Group Managed Service Accounts (gMSA) used for services such as Internet Information Services (IIS Web Server) might fail to authenticate.
- Remote Desktop connections using domain users might fail to connect.
- You might be unable to access shared folders on workstations and file shares on servers.
- Printing that requires domain user authentication might fail.
Today, Microsoft has released OOB emergency updates that Windows admins must install on all Domain Controllers (DCs) in affected environments. “You do not need to install any update or make any changes to other servers or client devices in your environment to resolve this issue. If you used any workaround or mitigations for this issue, they are no longer needed, and we recommend you remove them,” Microsoft advised. The OOB updates released today are available only via the Microsoft Update Catalog and will not be offered via Windows Update. Microsoft also released standalone updates which can be imported into Windows Server Update Services (WSUS) and Microsoft Endpoint Configuration Manager. The only affected platform still waiting for a fix is Windows Server 2008 R2 SP1; Redmond says that a dedicated update will be made available next week.
Detailed WSUS deployment instructions are available on the WSUS and the Catalog Site and Configuration Manager instructions on the Import updates from the Microsoft Update Catalog page. “If you are using security-only updates for these versions of Windows Server, you only need to install these standalone updates for the month of November 2022,” Microsoft added. “If you are using Monthly rollup updates, you will need to install both the standalone updates listed above to resolve this issue, and install the Monthly rollups released November 8, 2022, to receive the quality updates for November 2022.”