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Bootkitty: Analyzing the first UEFI bootkit for Linux
- jmclnx 2y agoFYI Related articles: https://news.ycombinator.com/item?id=42262525 https://news.ycombinator.com/item?id=42262525 https://news.ycombinator.com/item?id=42264655 https://news.ycombinator.com/item?id=42264655
- jmclnx 2y agoI found this a rather interesting read, nice. I cannot help but think the move to UEFI and Secure Boot made things less secure :(
- brookst 2y agoThe article says that Bootkitty does not work if Secure Boot is enabled. How do you figure Secure Boot made things less secure?
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- ghjfrdghibt 2y agoGonna assume it's because you have to disable it to run your operating system of choice, unless you beg Microsoft to let you.
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- brookst 2y agoSo that would be undesirable if true, but how would it be less secure than not having secure boot? Of course, most/all SB BIOSes enable setting your own platform key.
- athrowaway3z 2y agoBecause it can lock the door behind itself in an opaque hardware-dependent layer users have no control over. If i were to design security from the ground up it would be a small external sdcard for firmware and kernel (with a hardware r/w toggle), and optionally a external sdcard adapter that verifies the hash of the content. Everything else is as dumb as bricks and gets its firmware loaded from the sdcard. We didn't do that because secure boot was solving the problem of large orgs with remote administration in mind, and designed by orgs happy to sell yearly advanced cybersecurity protection shield plus certification subscriptions. Designing for remote administration by an IT department will.. increase the attack surface for attackers to remote administrate my device.
- fsflover 2y ago> If i were to design security from the ground up You might be interested in Librem Key, based on free firmware?
- KennyBlanken 2y agoYou only need disable it until you've got that OS installed, and then you can re-enable it. All the major linux distros have supported Secure Boot for years (which I was not aware of, and will now look into setting up!)
- microtonal 2y agoYou don’t need to disable it at all for distributions that support secure boot.
- psd1 2y agoI don't understand the tech: could it be the case that an older machine is missing CA roots that causes it to reject legitimately-signed code? I had to disable SB to boot the installer for either F39 or Mint 22, i forget which, on an old laptop.
- j0057 2y agoFUD: you can install your own keys, enable secure boot and run the OS of your choice.
- ghjfrdghibt 2y agoYou got a user friendly easy to follow guide? You can start by telling me what you mean by keys...
- brookst 2y agoIs the implication that anything that is more complicated is necessarily less secure? Because I think that turns security on its head. A deadbolt is more complicated than a door with no lock. We can argue about whether there is sufficient user demand and benefit to make secure boot easier for lay people. But that is completely orthogonal to whether it increases or decreases security of the system.
- jeroenhd 2y agoMost distros will run just fine without disabling secure boot. I don't think the *BSDs are supported by the shim loader yet, but even Gentoo boots with secure boot enabled, without loading any user keys.
- eightys3v3n 2y agoAnd significantly more complicated to setup and maintain in my limited experience :|
- Doe-_ 2y agoWhat makes you think that? Secure Boot prevents this rootkit from running and is the recommended mitigation: > Bootkitty is signed by a self-signed certificate, thus is not capable of running on systems with UEFI Secure Boot enabled unless the attackers certificates have been installed. > To keep your Linux systems safe from such threats, make sure that UEFI Secure Boot is enabled In fairness, the blog post confusingly says this in the next bullet point: > Bootkitty is designed to boot the Linux kernel seamlessly, whether UEFI Secure Boot is enabled or not, as it patches, in memory, the necessary functions responsible for integrity verification before GRUB is executed. However, this would still require Rootkitty to have gained execution already, which it wouldn't be able to if Secure Boot was enabled and the malicious actor's certificates weren't installed.
- joe_the_user 2y agoSecure boot prevents this proof of concept but it doesn't prevent all UEFI boot kits and this particular kit will likely evolve. On window: It took several years until the first two real UEFI bootkits were discovered in the wild (ESPecter, 2021 ESET; FinSpy bootkit, 2021 Kaspersky), and it took two more years until the infamous BlackLotus – the first UEFI bootkit capable of bypassing UEFI Secure Boot on up-to-date systems – appeared (2023, ESET). Per article.
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- B1ack3at_ 2y agoHello, I am the Bootkitty developer. The reason our bootkit is self-signed is because it uses the LogoFAIL vulnerability to register a MOK on the system to bypass secureboot, which is why our signature is included. I will leave an analysis article about LogoFAIL at the link below. https://www.binarly.io/blog/logofail-exploited-to-deploy-bootkitty-the-first-uefi-bootkit-for-linux https://www.binarly.io/blog/logofail-exploited-to-deploy-boo...
- otabdeveloper4 2y ago"Secure boot" is not actually meant to improve security. It exists as a moat to make it harder to install Linux on your (Microsoft) PC.
- exe34 2y agodoes it also help keep drm keys safe? that's how it works on Android, they even delete the 4k keys if you root your phone.
- telgareith 2y agoWhat!? Last I checked even with ring0 the system didn't have access to the WideVine keys. Talk about yet another reason to just pirate everything
- exe34 2y agoor buy them, but obtain a pirated version to recover what's yours when they lock you out.
- 1oooqooq 2y agoand identity. most of the world now replaced your credit card and government id with apps that rely on the OS assurences to prove you're yourself with vendor keys, mandatory selfies and such.
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- AzzyHN 2y agoIt's more secure than not having Secure Boot.
- 65a 2y agoUEFI itself is way too complex, has way too much surface (I'm surprised this didn't abuse some poorly written SMI handler), and provides too little value to exist. Secure boot then goes on to treat that place as a root of trust, which is security architecture mistake, but works ok in this case. This all could be a lot better.
- pluc 2y agoIt was just a way for Microsoft's partners to limit the ease with which one can install alternative OSes. Try explaining to your mother how to disable SecureBoot to install Ubuntu. It used to be a single sentence - pop the CD in and follow the instructions, but Microsoft couldn't have that. As is always the case with Microsoft, security is never the goal unless they gain a competitive advantage or make it harder for their customers to move away in the process.
- KennyBlanken 2y ago"It was just to keep people from installing something other than Windows" seems very counter-indicated by it taking ~7 years for a Windows UEFI bootkit to come out, and 13 years for one for Linux. ...and this bootkit is not able to work if Secure Boot is set up. UEFI is also a godsend in terms of fixing a lot of the legacy BIOS crap
- 1oooqooq 2y ago> and this bootkit is not able to work if Secure Boot is set up. wrong. > UEFI is also a godsend in terms of fixing a lot of the legacy BIOS crap that's like saying cutting the baby in half to end the dispute also solved the crying
- lmm 2y ago> UEFI is also a godsend in terms of fixing a lot of the legacy BIOS crap In my experience there's a lot more crap in UEFI than there ever was in BIOS, if only because there's so much more of it.
- hulitu 2y ago> UEFI is also a godsend in terms of fixing a lot of the legacy BIOS crap From a user perspective, no, it is not. Booting is far more complicated with UEFI.
- immibis 2y agoWhat do you mean? The boot menu now works with the mouse and I can click on the operating system I want to run.
- bri3d 2y agoWhat? I agree the move to UEFI added a huge new attack surface and that most UEFI implementations (notably, even the open source ones) are teeming with horrible bugs. And yes, then linking the trust architecture for Secure Boot so deeply with UEFI means that UEFI bugs are also Secure Boot bugs. But to say this is less secure? No way. Traditional BIOS-based MBR backdoors are like 1980s oldschool classic stuff. Most adversaries would require a good degree of development work to backdoor / root kit a PC they were given with Linux, Secure Boot, and an encrypted filesystem. With a BIOS based PC there would literally be nothing to do.
- zzo38computer 2y agoI think UEFI has many problems. However, you should not confuse separate (but related) issues from each other. If the initial booting functions can be altered by the operating system, that is a different issue (which perhaps UEFI makes it more severe). An internal hardware switch to disable this function would be helpful, and possibly a software function that the BIOS disables once the system starts (so it can only be altered by the BIOS setting menu, or by a BASIC or Forth in ROM or something like that). Functions being restricted by internal hardware switches would improve security, especially if also the initial booting functions are made less complicated too; if you are paranoid then you could also use glitter or whatever to detect hardware tampering.
- red-iron-pine 2y ago> An internal hardware switch to disable this function would be helpful For desktops and mobos, maybe. Gonna be hard to make that work for laptops and phones. But generally I'm in agreement. By the time I'm booting into and using the system the BIOS is no longer a discussion point; if I need to update it then I need to shut it down and get under the hood.
- nature556 2y agoWhat does the discovery of the Bootkitty UEFI bootkit for Linux systems suggest about the evolving landscape of cybersecurity threats?
- Brian_K_White 2y agoIt means "just trust us" is not and never was secure. Trustworthy people don't ask you to trust them.
- Joker_vD 2y agoIndeed. For example, none of those CA in the built-in bundle in my browser ever asked me to trust them, that's how I know they are trustworthy.
- Brian_K_White 2y agoYou were asked by the browser publisher to trust them. But those are merely defaults which you do posess ultimate control over, unlike the blobs and secrets in various bits of hardware.
- Joker_vD 2y agoNo, I wasn't "asked" by the browser publisher to trust them unless you use the word "ask" in a very broad (almost to the point of meaninglessness) sense: when I installed my browser, it simply started using its pre-packaged bundle of CA certificates. Which it regularly updates, I imagine, although it also never asked me about what the update source I'd like to use either. You can say that I implicitly trust the browser vendor's judgement in what CAs to trust, by the virtue of using the browser, and I'd agree with that. But saying that I was asked by the browser publisher to trust them? No, I disagree, I wasn't. It was a silent decision.
- Brian_K_White 2y agoAsk as in expect.
- Brian_K_White 2y agoI guess we need to go to back to socketed eeprom chips. Or just in general machines that are wholly controlled by the owner.
- voxadam 2y agoPreviously: https://news.ycombinator.com/item?id=42260346 https://news.ycombinator.com/item?id=42260346
- ddtaylor 2y agoThe researchers are keen to note things about this, but also likely want to avoid giving attackers "more ideas", which I feel limits the discussion. Plus, I highly doubt these attackers don't know everything we should be discussing. This is obviously a low hanging fruit and first PoC implementation. The fact that secure boot can "mitigate" some of this attack right now is mostly due to the attacker being lazy or deploying an unfinished product. The researchers describe this as "unless they install the attackers certificate", which is a nice way of saying that the attacker has not spent much time fishing through DKMS and abusing the keys used for this purpose. There are a lot of systems that are affected by this type of attack because for various purposes they have to sign their own modules. The most common example of this (until extremely recently, sort of) is Nvidia.
- 0xDEAFBEAD 2y ago>The fact that secure boot can "mitigate" some of this attack right now is mostly due to the attacker being lazy or deploying an unfinished product. The researchers describe this as "unless they install the attackers certificate", which is a nice way of saying that the attacker has not spent much time fishing through DKMS and abusing the keys used for this purpose. Can you explain, or link to a source explaining this?
- 1oooqooq 2y agoif you can add keys and sign things on the fly secure boot doesn't matter. it only protects you from downward payloads. if the one above the one that cares about secureboot is compromised its useless. you're confused because it's sold differently from this.
- 0xDEAFBEAD 2y agoThat all makes sense, but is it really that easy for an attacker to add keys? If so, the entire thing seems a little silly.
- josephcsible 2y ago
- grahamj 2y agoI think they put the Y in the wrong place; should have called it bootykit!
- fecal_henge 2y agoNot everyone is into pirates you know?
- grahamj 2y agohehe, or humour apparently
- cookiengineer 2y agoIt's kinda ridiculous reading the comments in here. This is a persistence stage exploit mechanism, meaning in order to install it, privilege escalation happened before that and it already got root rights. The people here that claim "secureboot prevented that". No, it didn't. A simple call to sbctl to sign the rootkit is missing, because, as every Linux device, you will have to have the signature keys available locally. Otherwise you can never update your kernel. That is the conceptual issue that cannot be fixed, and also not with TPM or whatever obscurity mechanism in between. Linux needs to be a rootless system, meaning that there needs to be a read only partition that root can never read. That would limit access to this kind of thing to physical access or the kernel ring at the very least. Technically, this was the intent of efivarfs, but look at where vendor firmware bugs got us with this.
- bscphil 2y ago> The people here that claim "secureboot prevented that". No, it didn't. A simple call to sbctl to sign the rootkit is missing, because, as every Linux device, you will have to have the signature keys available locally. Otherwise you can never update your kernel. If, hypothetically, you were using a system without custom keys, e.g. with a third party kernel trusted via the Microsoft / Red Hat shim program, [1] wouldn't you be safe, so long as secure boot was enabled? The bootkit would not be able to sign itself with a trusted key since the private key would never exist on the system to begin with. Obviously, I'm aware that this approach has other problems and has had vulnerabilities in the past. [1] https://wiki.ubuntu.com/UEFI/SecureBoot https://wiki.ubuntu.com/UEFI/SecureBoot
- salawat 2y agoYou don't need to do your signing locally, it is possible to build your network around a build machine that does the signing for you. That being said, SecureBoot has always been security theater for anyone that isn't a major OS manufacturer or industry player. The fact is, as soon as cryptography comes into the picture the majority of the computing populace have already left the conversation.
- mjg59 2y ago
- rob_c 2y agoNeat-o wonder where this was discovered and what telemetry is being used to say it isn't used in the wild (guessing commercial anti-v products)
- B1ack3at_ 2y agoHello everyone, I am the developer of BootKitty. I am studying IT in Korea and I am making bootkit as a private project in BOB, a security program training. If you find it hard to believe that I am a developer, I can prove it. If you have any questions about BootKitty, please ask me :)