Microsoft may take up to a year to fix 0-day boot bug

Emre Çitak
May 12, 2023

Microsoft finds itself in a race against time as it tackles a significant and alarming 0-day secure boot bug that has sent shockwaves through the tech community. This critical vulnerability, known as CVE-2023-24932, has resurfaced with another actively exploited workaround, affecting systems running Windows 10, Windows 11, and various Windows Server versions, dating all the way back to Windows Server 2008.

With the potential to undermine the security of countless devices, Microsoft's response to this threat has become a top priority.

Unmasking the BlackLotus Bootkit and CVE-2023-24932

At the forefront of this security concern is the notorious BlackLotus bootkit. This real-world malware has gained infamy for its ability to bypass Secure Boot protections, granting hackers the ability to execute malicious code even before the Windows operating system and its essential security measures come into play.

Secure Boot, enabled by default on numerous Windows PCs for over a decade, including popular brands like Dell, Lenovo, HP, and Acer, has been a fundamental line of defense. However, the emergence of BlackLotus has shattered the illusion of invulnerability.

Windows 0-day boot bug
Windows 0-day boot bug can be exploited in leading manufacturers

The vulnerability exploited

Microsoft warns that the 0-day secure boot bug can be exploited either through physical access to a system or by obtaining administrator rights. This makes the vulnerability a grave concern for both physical computers and virtual machines that have Secure Boot enabled. What sets this fix apart from other critical Windows updates is the decision to keep it disabled by default for several months after installation.

This cautious approach aims to minimize any potential disruptions, as the update brings irreversible changes to the Windows boot manager, which may render existing Windows boot media unbootable.

Navigating the patching journey ahead

Microsoft has released a series of support articles emphasizing the importance of enabling the fix correctly to avoid system disruptions and startup failures. Once the fix is enabled, older bootable media lacking the necessary updates will no longer function on the system.

This includes Windows installation media such as DVDs and USB drives created from Microsoft's ISO files, custom Windows install images maintained by IT departments, full system backups, network boot drives, stripped-down boot drives using Windows PE, and even recovery media bundled with OEM PCs.

To ensure a smooth transition and minimize the risk of system failures, Microsoft has designed a phased approach for rolling out the update over the coming months. The initial patch release demands significant user involvement, requiring the installation of May's security updates and a meticulous five-step manual process involving the application and verification of "revocation files".

These files update the system's hidden EFI boot partition and registry, establishing trust in the patched bootloader versions while revoking trust for older, vulnerable variants.

Windows 0-day boot bug
Microsoft has published multiple guides to minimize the effects of Windows 0-day boot bug

Microsoft's streamlined fix update is coming in July

Looking ahead, a second update is planned for July, streamlining the process of enabling the fix. The ultimate milestone is set for the first quarter of 2024 when the fix will be automatically enabled by default, rendering older boot media incompatible with all patched Windows systems. Microsoft acknowledges the possibility of accelerating this timeline, but the specifics remain unclear.

Jean-Ian Boutin, ESET's director of threat research, has underscored the severity of the BlackLotus bootkit and similar threats, highlighting their ability to compromise secure boot mechanisms and gain control over the critical early phase of system startup.

This latest fix sheds light on the ongoing challenges of addressing low-level Secure Boot and UEFI vulnerabilities. Recent incidents, such as the leakage of signing keys in a ransomware attack targeting computer and motherboard manufacturer MSI, further emphasize the complexity and importance of promptly addressing such issues.


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  1. Dan Donx said on January 15, 2023 at 10:29 am

    What mental age of reader are you targeting with the first sentence? 10?

    Why not write an article on how to *avoid* upgrading from W10 to W11. Analogous to those like me who avoided upgrading from 7 to 10 for as long as possible.

    If your paymaster Microsoft permits it, of course.

  2. Dexter said on January 15, 2023 at 11:14 am

    5. Rufus
    6. Ventoy

    PS. I hate reading these “SEO optimized” articles.

    1. cdr said on January 15, 2023 at 3:32 pm

      I used Rufus to create an installer for a 6th gen intel i5 that had MBR. It upgraded using Setup. No issues except for Win 11 always prompting me to replace my local account. Still using Win 10 Pro on all my other PCs to avoid the bullying.

  3. sv said on January 15, 2023 at 6:40 pm

    bit pointless to upgrade for the sake of upgrading as you never know when you’ll get locked out because ms might suddenly not provide updates to unsupported systems.

    ps…. time travelling?
    written. Jan 15, 2023
    Updated • Jan 13, 2023

    1. Martin Brinkmann said on January 16, 2023 at 5:49 am

      This happens when you schedule a post in WordPress and update it before setting the publication date.

  4. Anonymous said on January 16, 2023 at 8:24 am

    Anyone willing to downgrade to this awful OS must like inflicting themselves with harm.

  5. basingstoke said on January 16, 2023 at 11:18 am

    I have become convinced now that anybody who has no qualms with using Windows 11/10 must fit into one of the following brackets:

    1) Too young to remember a time before W10 and W11 (doesn’t know better)

    2) Wants to play the latest games on their PC above anything else (or deeply needs some software which already dropped W7 support)

    3) Doesn’t know too much about how computers work, worried that they’d be absolutely lost and in trouble without the “”latest security””

    4) Microsoft apologist that tries to justify that the latest “features” and “changes” are actually a good thing, that improve Windows

    5) Uses their computer to do a bare minimum of like 3 different things, browse web, check emails, etc, so really doesn’t fuss

    Obviously that doesn’t cover everyone, there’s also the category that:

    6) Actually liked W7 more than 10, and held out as long as possible before switching, begrudgingly uses 10 now

    Have I missed any group off this list?

    1. Heinz Strunk said on September 19, 2023 at 3:57 pm

      You have missed in this group just about any professional user that uses business software like CAD programs or ERP Programs which are 99% of all professional users from this list.

      Linux doesn’t help anyone who is not a linux kid and apple is just a fancy facebook machine.

  6. ilev said on August 24, 2023 at 7:34 pm

    Microsoft has removed KB5029351 update

    1. EP said on August 24, 2023 at 9:21 pm

      only from windows update though
      KB5029351 is still available from the ms update catalog site

  7. Anonymous said on August 24, 2023 at 11:05 pm

    1. This update is labaled as PREVIEW if it causes issues to unintelligent people, then they shouldn’t have allowed Preview updates ot install.

    2. I have installed it in a 11 years old computer, and no problems at all.

    3. Making a big drama over a bluescreen for an updated labeled as preview is ridiculous.

    This is probably another BS internet drama where people ran programs and scripts that modified the registry until they broke Windows, just for removing stuff that they weren’t even using just for the sake of it.
    Maybe people should stop playing geeks and actually either use Windows 10 or Windows 11, but don’t try to modify things just for the sake of it.

    Sometimes removing or stopping things (like defender is a perfect example) only need intelligence, not scripts or 3rd party programs that might mess with windows.

  8. john said on August 24, 2023 at 11:17 pm

    Windows 11 was a pointless release, it was just created because some of the Windows team wanted to boost sales with some sort of new and improved Windows 10. Instead, Microsoft cannot support one version well let alone two.

    1. John G. said on August 25, 2023 at 12:08 pm

      Windows 11 is the worst ugly shame by Microsoft ever. They should release with every new W11 version a complete free version of Starallback inside just to make this sh** OS functionally again.

  9. EP said on August 25, 2023 at 3:10 pm

    motherboard maker MSI has recently released a statement regarding the “unsupported processor” blue screen error for their boards using Intel 600/700 series chipsets & to avoid the KB5029351 Win11 update:–UNSUPPORTED-PROCESSOR–Error-Message-of-Windows-11-Update-KB5029351-Preview-142215

  10. EP said on August 29, 2023 at 7:32 pm

    check out the following recent articles:

    Neowin – Microsoft puts little blame on its Windows update after UNSUPPORTED PROCESSOR BSOD bug:

    BleepingComputer – Microsoft blames ‘unsupported processor’ blue screens on OEM vendors:

  11. Leonard Britvolli said on August 30, 2023 at 10:33 pm

    While there may be changes or updates to the Windows 10 Store for Business and Education in the future, it is premature to conclude that it will be discontinued based solely on rumors.

  12. sembrador said on September 5, 2023 at 9:32 pm

    My advice, I left win 15 years ago. Now I’m a happy linux user (linuxmint) but there is Centos, Fedora, Ubuntu depending on your needs.

  13. EP said on September 6, 2023 at 11:55 am

    motherboard maker MSI has recently released new BIOS/firmware updates for their Intel 600 & 700 series motherboards to fix the “UNSUPPORTED_PROCESSOR” problem (Sept. 6):–UNSUPPORTED-PROCESSOR–caused-BSOD-on-MSI-s-Intel-700-and-600-Series-Motherboards-142277

  14. Raphael Benzo said on September 24, 2023 at 9:52 pm

    I try to disable the Diagnostics Tracking Service (Connected Devices Platform User Services) but it wont let me disable it, any help will be greatly appreciated.
    Tank you for your help

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