Microsoft reports several bootloader vulnerabilities

(microsoft.com)

82 points | by hacknslack 4 days ago ago

34 comments

  • fuzzfactor 3 hours ago ago

    Well if Microsoft was as serious about security as they could be, they would have made sure the NT6 boot routine would boot Linux without needing Grub a long time ago.

    With the resources they have, and these unique findings AI has helped them discover, they should now be in the ideal position to rapidly correct this deficiency in their own bootloader, so that nobody will ever need to use Grub again.

    With this level of expertise, now enhanced by AI, and so much effort already behind them so far, it shouldn't take much to push this over the finish line, provided they have an effective enough organization when it comes to enhancing the security of PC users overall. After all, they don't even have to worry about addressing Macs.

    I know the engineers are brilliant enough by far, and with nothing holding them back, we should be able to expect a minor revision of of the NT bootloader like this to be arriving any day now.

    According to what I see in the article, this would be one of the most timely & useful security patches to show up on Windows Update, I hope they don't drop the ball on this one.

    Patch Tuesday is next week but they seem so close they could probably push this critical correction out before that, so watch for it :)

    • mystified5016 2 hours ago ago

      I've always thought it was exceptionally clear that Microsoft emphatically does not want you to dualboot.

      That's why we got secure boot and why windows absolutely clobbers any other bootloaders during install, updates, and random points in between. It's why we have WSL.

      I'll bet good money that Microsoft never even considers what you propose. It's antithetical to the mission of "lock all possible users into ad revinue streams". Microsoft won't get their windows ad impressions if they allow you to use a different OS on the hardware you own.

    • cmurf an hour ago ago

      I don't understand why you think GRUB is required. Or what boot sequence (or use case) involves UEFI > NT6 > GRUB > linux.

      Are you wanting bootmgr.efi to learn how to read arbitrary Linux filesystems, bootloader configurations, and EFISTUB? Why?

      Windows supports setting a one time boot using a UEFI BootNext NVRAM variable, directly boots shim.efi, doesn't involve bootmgr.efi

    • dismalaf an hour ago ago

      > nobody will ever need to use Grub again.

      I mean, I replaced Grub with systemd-boot awhile back...

  • zelon88 3 hours ago ago

    "To demonstrate how efficient our product, CoPilot is, we've decided to use it to uncover vulnerabilities in competing products."

    Gee, how clever and thoughtful.

  • usr1106 12 hours ago ago

    That grub has security vulnerabities does not surprise me, it's just too big. That's why Lennart recommends systemd-boot. (Incidently a Microsoft employee, but I have no information that he would have been involved in these discoveries.) U-boot again is typical embedded software, a field generally known more for hacks than strict programming practices. So I cannot say I would be shocked. That said, I would be surprised if systemd-boot or Microsoft's loader had zero vulnerabilities hiding somewhere.

    When does Microsoft open their source for searching vulnerabilities?

    • bayindirh 10 hours ago ago

      GRUB is too big? Maybe because it's 30 years old and can boot at least 11 architectures.

      ...and what systemd-boot is? A UEFI only boot menu which gets its data from UEFI only.

      I mean comparing two different things and claiming the more featured one too big is mental gymnastics to put it politely.

      GRUB having vulnerabilities is not surprising, esp. when the thing is written at an age where computers were completely different things, programming and requirements wise, but insinuating that systemd-boot is the ultimate replacement is, eh, a bit underhanded. Esp. when it comes from Lennart, whose systemd is too big and encompassing for an init system.

      It's the pot calling the kettle black, heh.

    • FirmwareBurner 12 hours ago ago

      >That's why Lennart recommends systemd-boot.

      The creator of SystemD recommends systemd-boot? Seems legit and unbiased.

      • ahartmetz 9 hours ago ago

        There is probably an overlong yet superficial, easy to read post on his blog about it.

      • onli 10 hours ago ago

        Yeah, and because grub is too big. Says systemd, of all places.

        • jonathanstrange 10 hours ago ago

          Pulseaudio still doesn't work reliably.

          • bayindirh 10 hours ago ago

            I think Pipewire has completely replaced Pulseaudio where it matters.

            • ahartmetz 9 hours ago ago

              Yes, PulseAudio works great since it's actually PipeWire.

  • greatgib 11 hours ago ago

    To start with, security of "secure boot" there is a joke because anyway all os have to be signed by Microsoft itself. So anyone with they certificate key can do whatever they want.

    And btw, not that long ago it was released by researchers than more than 200 platforms from diverse but main laptops and servers manufacturers were still using leaked keys for signing their boot loaders...

    • donnachangstein 10 hours ago ago

      > security of "secure boot" there is a joke because anyway all os have to be signed by Microsoft itself.

      Is Apple a joke because they sign the root of trust for their devices? Someone has to be the root authority. Honestly I trust MS more than I do Google or VerisignDigicert. They are the least likely to intentionally break things.

      The reason MS controls the root and not Red Hat etc. is because the Linux camp spent years arguing back and forth about exactly how much they hate secure boot - like an HOA arguing over paint colors - instead of presenting solutions.

      > So anyone with they certificate key can do whatever they want.

      this is literally how PKI works

      Somehow I think MS put a little more thought into their PKI design than whatever you're trying to convey here. What were the other options? Store it on a Yubikey sewn into rms's beard?

      People are quick to dismiss secure boot simply because they refuse to understand it.

      • fuzzfactor 2 hours ago ago

        All evidence has always pointed to the purpose of Microsoft SecureBoot being introduced primarily as an obstacle to continued use of Windows 7 as well as Linux on PC's going forward when Windows 8 PC's were released.

        Not like there's any question.

        Overwhelmingly more so than for "security" purposes.

        Any lesser understanding of Microsoft SecureBoot, well, I understand.

        I've seen that kind of that kind of refusal before.

      • rcxdude 9 hours ago ago

        >Someone has to be the root authority

        No-one has to be, and it certainly doesn't need to be anyone but the owner of the machine.

        • kbolino 4 hours ago ago

          You can enroll your own certificates as long as you have unlocked firmware. However, in order for vendor ISOs to boot without modification, they need to be signed by some trusted root beyond your control.

        • donnachangstein 9 hours ago ago

          > No-one has to be, and it certainly doesn't need to be anyone but the owner of the machine.

          Technically the web should work with self-signed certificates. But that is likewise impractical.

      • greatgib 8 hours ago ago

        Basically a little bit yes. Especially for an entity located in US and with strong links to the basic government.

        But in the case of secure boot, this is worse, because Microsoft is just a "software" editor. But its root certificate and probably a few random others are distributed in countless of devices produced by manufacturers unrelated to them, but also, a few number of software distributors will also have subkeys to be able to sign their os/software. All of that, with zero transparency.

        And in the end, if I buy a Lenovo laptop, to have Linux OS running on it, there is no reason and no trust to have my OS be signed by Microsoft, that has the key to run whatever they want on my laptop. Think about it and you will see that it makes no sense at all, if you don't trust Microsoft for your OS, to have to trust them for ensuring a secure boot...

        • AstralStorm 8 hours ago ago

          Technically you can revoke the default root of trust and install your own.

          Then manually sign your bootloader.

          This feature is available at least in my Gigabyte mainboard, but is not particularly easy to use, which is why bootloaders come pre-signed with a known root of trust. There's nothing stopping the installer from generating the root of trust on the fly, except for the default settings in many machines.

          Can also preload measurements for hardware while at it so that nobody swaps a PCIe device for an evil twin.

    • greatgib 4 hours ago ago
    • vladvasiliu 10 hours ago ago

      Some PCs are able to use your own keys, which can be used to sign your bootloader. This has worked well for me with various HP computers (EliteBooks and EliteDesks). One of those, which only runs Linux, will refuse to boot the Windows installer. On my work laptop, I've also added the Windows key (not the 3rd party one) so I can dual-boot.

      I understand some computers may not support this as well, so YMMV.

  • moktonar 2 hours ago ago

    What they probably don’t tell you is that they also found critical vulnerabilities in their own boot loader and fixed them silently

  • aaronmdjones 13 hours ago ago

    The link for U-Boot CVE-2025-26729 is actually 2 separate links that lead to different vulnerabilities depending on which half of it you click.

    Odd. I wonder if the article was written by AI.

  • gnabgib 15 hours ago ago

    Title: Analyzing open-source bootloaders: Finding vulnerabilities faster with AI

  • ncr100 4 days ago ago

    Nice to see Microsoft boosting open source operating system practices. (May be a little anti monopoly politicking, ahem.)

    Makes me trust open source operating systems more!

    • randombits0 4 days ago ago

      It’s not an article about vulnerable boot loaders. It’s an ad for their AI offering. That they turned their AI loose on some boot loaders is not material to the intended affect of the ad.

      • xmodem 8 hours ago ago

        I think that finding and fixing this many vulns is a worthwhile achievement, no matter how they did it. But it does detract from the quality of the article that they are pushing CoPilot so heavily.

      • blibble 15 hours ago ago

        agree it's an ad

        but if they sent the AI through all that ancient code and that's all they found it's not a good advertisement

        • pndy 2 hours ago ago

          This whole thing is weird: submitting account registered 3 days ago, no other activity than this link added on coincidentally, MS anniversary.

      • Harvesterify 3 days ago ago

        Did you read the OP link ? They go in far more details than just presenting what they did with AI, and they actually found several exploitable vulnerabilities, not just with AI, but with other techniques such as code analyzing or fuzzing.

        AI is in he title, but the content is not entirely revolving around it.

  • jonathanstrange 10 hours ago ago

    I consider the ability to bypass secure boot a feature, not a bug.

  • neuroelectron 12 hours ago ago

    if you want to security, I think a generic boot loader isn't really a realistic target. A boot loader should be specific to the hardware. If you want a generic boot loader, you need to integrate perfected boot loaders for each hardware.