Security Vulnerability: CVE-2023-24932 BlackLotus bootkit
This document (000021066) is provided subject to the disclaimer at the end of this document.
Environment
Any UEFI secure boot enabled installation.
Situation
A UEFI bootkit called BlackLotus has been spotted in the wild, which uses buggy secure boot binaries to bypass the UEFI secure boot chain.
While this component is not shipped by SUSE, to ensure the integrity of the UEFI secure boot chain the affected components will need to be excluded from the UEFI secure boot space.
This is done via a so called "DBX" file which blocks UEFI binaries using signatures/hashes.
While this component is not shipped by SUSE, to ensure the integrity of the UEFI secure boot chain the affected components will need to be excluded from the UEFI secure boot space.
This is done via a so called "DBX" file which blocks UEFI binaries using signatures/hashes.
Resolution
These DBX file updates can be delivered and deployed in different ways:
1. Via BIOS or Windows updates
The DBX file can be delivered via BIOS updates or in case of a dual boot system are delivered with Windows updates.
If installed via BIOS or Windows updates, no additional deployment on Linux is required.
2. Via the firmware update tool (fwupd)
Download the current DBX revocation list from https://uefi.org/revocationlistfile for the respective hardware platform.
Use "fwupdmgr install x64_DBXUpdate.bin" and follow the prompts.
NOTE: This update method only works starting with SUSE Linux Enterprise 15 SP3 based and newer products.
Note: This is a manual deployment and only needed in case of concerns about UEFI bootkits as they do not represent a
common attack scenario.
1. Via BIOS or Windows updates
The DBX file can be delivered via BIOS updates or in case of a dual boot system are delivered with Windows updates.
If installed via BIOS or Windows updates, no additional deployment on Linux is required.
2. Via the firmware update tool (fwupd)
Download the current DBX revocation list from https://uefi.org/revocationlistfile for the respective hardware platform.
Use "fwupdmgr install x64_DBXUpdate.bin" and follow the prompts.
NOTE: This update method only works starting with SUSE Linux Enterprise 15 SP3 based and newer products.
Note: This is a manual deployment and only needed in case of concerns about UEFI bootkits as they do not represent a
common attack scenario.
Status
Security Alert
Additional Information
References:
Knowledgebase article from Microsoft:
https://support.microsoft.com/en-us/topic/kb5025885-how-to-manage-the-windows-boot-manager-revocations-for-secure-boot-changes-associated-with-cve-2023-24932-41a975df-beb2-40c1-99a3-b3ff139f832d
Upstream UEFI DBX revocation files:
https://uefi.org/revocationlistfile
Knowledgebase article from Microsoft:
https://support.microsoft.com/en-us/topic/kb5025885-how-to-manage-the-windows-boot-manager-revocations-for-secure-boot-changes-associated-with-cve-2023-24932-41a975df-beb2-40c1-99a3-b3ff139f832d
Upstream UEFI DBX revocation files:
https://uefi.org/revocationlistfile
Disclaimer
This Support Knowledgebase provides a valuable tool for SUSE customers and parties interested in our products and solutions to acquire information, ideas and learn from one another. Materials are provided for informational, personal or non-commercial use within your organization and are presented "AS IS" WITHOUT WARRANTY OF ANY KIND.
- Document ID:000021066
- Creation Date: 10-May-2023
- Modified Date:10-May-2023
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- SUSE Linux Enterprise Server
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