(2019)
The biggest weakness of secure boot was always third-party vendors shipping "insecure" bootloaders. It's a lot of work to verify signatures for every bit of data that gets loaded, especially on the PC platform.
(2019)
The biggest weakness of secure boot was always third-party vendors shipping "insecure" bootloaders. It's a lot of work to verify signatures for every bit of data that gets loaded, especially on the PC platform.
Thre original secure boot design would have had insecure bootloaders get blacklisted the moment abuse could be detected.
Microsoft then made that system entirely useless by signing code that could be used to load unsigned code, like demonstrated here.
They then also refused to blacklist their own broken bootloader to save sysadmins the time (who would need to deploy new recovery images and boot media containing the fixed bootloader). That vulnerable bootloader is particularly bad because it can be used to have the TPM unlock itself and give up the Bitlocker key, which the Linux loaders shouldn'tbe capable of even if they apply the bypass mentioned in the article.
In a world where Microsoft cared about secure boot, they would blacklist the vulnerable Linux loaders as well as their own old bootloaders. Why Microsoft? Because they signed the files in the first place, only they can rescind the signatures. In that world, Linux users would call for Bill Gates' head for securing their security feature and sysadmins would be out for Steve Ballmer's blood for breaking their complex custom recovery system that nobody dares touch.
Now we'll be stuck in the worst of both worlds.
>They then also refused to blacklist their own broken bootloader to save sysadmins the time (who would need to deploy new recovery images and boot media containing the fixed bootloader).
Source? The OP suggests they expect it to be blacklisted
>I assume that Kaspersky bootloader signature certificate will not live long, and it will be added to global UEFI certificate revocation list, which will be installed on computers running Windows 10 via Windows Update
If you search around you'll also find that microsoft does publish secure boot revocations, contrary to what you claim.
https://github.com/fwupd/dbx-firmware
They blacklist some bootloaders, but it takes them forever. CVE-2023-24932 (from May 2023) had a fix available a year later (June 2024), had the update broadly made available through standard updates in 2025 (2 years later) and doesn't automatically install it today.
You might think the 2025 update will solve the problem, but:
> Before following these steps for applying the mitigations, install the Windows monthly servicing update released on July 8, 2025, or a later update on supported Windows devices. This update includes mitigations for CVE-2023-24932 but they are not enabled by default. All Windows devices should complete this step regardless of your plan to enable the mitigations.
The current status for the update (https://support.microsoft.com/en-us/topic/how-to-manage-the-...) says:
> The Enforcement Phase will not begin before January 2026, and we will give at least six months of advance warning in this article before this phase begins. When updates are released for the Enforcement Phase, they will include the following:
Basically, unless your company and sysadmin have enforced this fix (i.e. you're a home user), Microsoft hasn't revoked their keys.
Then there's CVE-2024-38058, a similar attack. Microsoft tried to roll out a fix, but that broke compatibility, and the fix was then rolled back. Again, that problem can be fixed with the solution for the previous CVE, but that is still not deployed by default.
https://neodyme.io/en/blog/bitlocker_screwed_without_a_screw... describes the TPM2 attack in detail as well as mitigations and solutions much better than I can.
A better design would not involve a small default-trusted set of keys in the first place. If the signers were diverse and on equal footing, with users choosing who to trust, a single bad bootloader being signed would not compromise nearly the whole ecosystem.
I feel like this isn’t the best moment to call Bill Gates. Or maybe yes, maybe he’ll open source Windows at this point, who knows!
Third party? Black Lotus was the first case we saw actually targeting individuals, and that was a vulnerability in the Windows bootloader.