Reminder: Changes coming to Windows Boot Manager revocations for Secure Boot, April 9, 2024

Administrators should observe mitigations and security enforcement requirements coming into effect with Windows updates released on and after April 9, 2024. Devices running Windows updates released July 11, 2023 or later include security measures designed to protect vulnerable boot managers against a Secure Boot bypass vulnerability disclosed in CVE-2023-24932. Secure Boot is a Windows security feature designed to protect devices from bootkit malware.

Windows security updates include options to manually enable protections against Secure Boot bypass beginning July 11, 2023. Additional protections and deployment phases for these protections are coming with updates being released on April 9, 2024, and throughout 2024. For detailed information, see KB5025885: How to manage the Windows Boot Manager revocations for Secure Boot changes associated with CVE-2023-24932.
When will this happen:
April 9, 2024 or later – Third Deployment Phase
  • Windows updates released on and after this date will provide new mitigations to block additional vulnerable boot managers.
October 8, 2024 or later – Mandatory Enforcement Phase
  • Windows updates released on and after this date that are installed to affected systems will enforce the Code Integrity Boot policy and Secure Boot disallow list revocations related to this hardening. There will be no option to disable this enforcement after this update.
The Mandatory Enforcement Phase described above is the final phase of these security hardening measures.
What you need to do to prepare:
Administrators should determine whether it’s important to enable protections now or wait for a future update from Microsoft. It’s also important to understand the options available for configuring these security requirements in your environment. See the resources available in the Additional information section below.
Additional information:

Message ID: MC714379

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