Some Windows updates might actually hurt your security

Windows 11 Update showing on laptop in an office
(Image credit: TechRadar)

Following the deployment of its latest round of Patch Tuesday (opens in new tab) updates, Microsoft is currently investigating a known issue that leads to authentication failures for a number of Windows services.

According to BleepingComputer (opens in new tab), the software giant began looking into these issues after Windows admins began sharing reports of certain policies failing after installing its May 2022 Patch Tuesday updates. 

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These admins reported that after installing the updates they began seeing the following error message: "Authentication failed due to a user credentials mismatch. Either the user name provided does not map to an existing account or the password was incorrect."

While this issue impacts client and server Windows platforms and systems including those running Windows 11 (opens in new tab) and Windows Server 2022 (opens in new tab), Microsoft says that it is only triggered after updates are installed on servers that are being used as domain controllers (opens in new tab)

In a support document (opens in new tab), the company explained that authentication failures may occur for a number of services including Network Policy Server (NPS), Routing and Remote access Service (RRAS), Radius, Extensible Authentication Protocol (EAP), and Protected Extensible Authentication Protocol (PEAP).

Failure to authenticate

In a separate support document (opens in new tab), Microsoft went into further detail regarding these service authentication problems by explaining that they are caused by security updates that address privilege escalation vulnerabilities in Windows Kerberos and its Active Directory Domain Services.

The vulnerability in Microsoft’s Active Directory Domain Services (tracked as CVE-2022-26923 (opens in new tab)) has a high severity CVSS score of 8.8 and if left unpatched, can be exploited by an attacker to elevate the privileges of an account to those of a domain admin. Meanwhile, the vulnerability in Windows Kerberos (tracked as CVE-2022-26931 (opens in new tab)) also has a high severity CVSS score of 7.5.

To mitigate these authentication issues, Microsoft suggests that Windows admins manually map certificates to a machine account in Active Directory (opens in new tab) though it also suggests using the Kerberos Operational log to see which domain controller is failing to sign in.

Still though, one Windows admin that spoke to BleepingComputer said that the only way they were able to get some of their users to log in following the installation of the latest Patch Tuesday updates was by disabling the StrongCertificateBindingEnforcement registry key by setting it to 0. This registry key is used to change the enforcement mode of the company’s Kerberos Distribution Center (KDC) to Compatibility mode.

Now that Microsoft is actively investigating these issues and coming up with workarounds, a proper fix should arrive soon or at least during its next Patch Tuesday updates in June.

Via BleepingComputer (opens in new tab)

Anthony Spadafora

After working with the TechRadar Pro team for the last several years, Anthony is now the security and networking editor at Tom’s Guide where he covers everything from data breaches and ransomware gangs to the best way to cover your whole home or business with Wi-Fi. When not writing, you can find him tinkering with PCs and game consoles, managing cables and upgrading his smart home.