While it is certainly an interesting bug, I kinda feel that the title is click bait? Because this `cryptsetup luksSuspend` from what I understood is not really officially supported but an extension done in Debian, so if anything this regression only affected Debian? I am not sure if you can blame the kernel for something that is not supported or even widely tested.

I still find this impressive, and it is nice that we now have a test (NixOSTests BTW are awesome, I agree with OP) to avoid this regression from coming back. But from the title it seems to be a widespread issue, not something that affects only one Distro.

• IngoBlechschmid

  today at 5:11 PM

  Sorry, aimed for a technically precise title and didn't want to bait clicks.

  Yes, this does not affect people on stock configurations for the plain reason that they wouldn't expect the volume key to be safe during suspend anyway.

  Debian's solution was ported to several (most?) other distributions and I guess quite a few people maintained private ports.

  The thread-keyring(7) manpage promises: "A thread keyring is destroyed when the thread that refers to it terminates." For their key upload (from userspace to kernelspace) mechanism, the cryptsetup project relied on this property; but kernel 6.9 introduced a regression invalidating this property.

I don't see any other way? When you sleep (suspend to RAM), everything is stored in RAM and is encrypted but the master key is present in kernel memory (if I recall correctly).

However, if you hibernate (suspend to disk) the entire contents of RAM (including the master key) is written/encrypted to disk and the RAM is cleared.

When you wake the machine up you have to re-enter the passphrase to decrypt the master key to re-load disk contents back to memory.

• IngoBlechschmid

  today at 4:21 PM

  Yes, if you simply suspend your laptop on most stock Linux distributions, then everything including the master key is still kept in memory. But Debian pioneered the (optional) cryptsetup-suspend addon. This issues a luksSuspend command which is supposed to wipe the key from memory, and on resume asks you to resupply your passphrase.

  Up to kernel 6.8, this worked as described; starting with kernel 6.9, it silently didn't.

  • herywort

    today at 4:54 PM

    So you would still be asked for a passphrase, even though it's already available?

    • IngoBlechschmid

      today at 4:57 PM

      Exactly. Cryptsetup wouldn't know about the extra copy of the volume key in kernel memory. Which is why, dramatically, it appeared secure ("surely I wouldn't be asked to resupply the passphrase if the volume key is still in memory, right?").

      • pedrocr

        today at 5:18 PM

        It was still more secure than the default if I understand this correctly. On resume from suspend the laptop would still be locked by the encryption key and without access to the disk even if you can somehow circumvent the lock. The only insecurity was that somewhere in the kernel memory the key still exists so if you can somehow extract that from the live system you can unlock it.

        • IngoBlechschmid

          today at 5:39 PM

          Yes, you are right: LUKS encryption protests your data at rest. An attacker which steals your disk can only gain little, like the information that you have used LUKS (unless you put your LUKS headers elsewhere, separated from the disk) and perhaps disk and disk sector usage statistics.

  • naturalmovement

    today at 4:27 PM

    FYI: VeraCrypt is not the defacto encryption software for Windows.

    • IngoBlechschmid

      today at 4:29 PM

      Oh, which one is it?

      (You don't mean BitLocker, right?)

      • naturalmovement

        today at 4:31 PM

        It absolutely is and they have most the enterprise market.

        • IngoBlechschmid

          today at 4:49 PM

          Okay, yes, sure. It definitely is the most-used encryption software for Windows.

          But I would never trust it a second, being proprietary and known for issues. You likely know that, but for the benefit of others:

          38C3 - Windows BitLocker: Screwed without a Screwdriver https://media.ccc.de/v/38c3-windows-bitlocker-screwed-withou... https://www.youtube.com/watch?v=5eNtT2p12cM

          • noinsight

            today at 5:25 PM

            If you’re at all serious about security and not user convenience, you deploy BitLocker with a PIN instead of TPM only. And then a whole class of vulnerabilities goes away.

          • bri3d

            today at 5:23 PM

            The issues you linked with BitLocker are obvious properties of BitLocker-with-SecureBoot-only architecture. If you configure Linux that way, you get similar issues (for example, it's pretty easy to mis-configure TPM sealed disk encryption on Linux to still allow a recovery shell, which will run with the disk unsealed).

            BitLocker with a password (the equivalent of the LUKS configuration in question) does not share these issues.

            • veeti

              today at 6:15 PM

              Bitlocker with a password has always felt like a second class citizen to me. You have to dig into a bunch of group policies to use it. Maybe most people don't even realize it exists.

          • saidnooneever

            today at 5:11 PM

            veracrypt lost their drivers license so afaik you should avoid it since it cannot update its drivers any longer. didnt see any news about them reacquiring that license

            • snailmailman

              today at 5:19 PM

              Assuming this is what you are referring to, it was resolved within a few days. The incident being resolved just didn't make headlines. https://sourceforge.net/p/veracrypt/discussion/general/threa...

        • nacs

          today at 4:44 PM

          Reminder that by using Bitlocker, you're using a closed source encryption for which Microsoft will happily hand out your recovery key on request.

          https://www.forbes.com/sites/thomasbrewster/2026/01/22/micro...

          • andrewpiroli

            today at 4:53 PM

            Only if you store your key with Microsoft, which is not required or the default if you're using a local account which I assume most privacy sensitive people are.

            • gruez

              today at 5:17 PM

              Not to mention that unless the bitlocker activation flow changed recently, it specifically asks you how to store your backup keys, with a choice given been local options (eg. usb drive, printing it off, etc.) and saving it to your microsoft account.

          • briHass

            today at 5:00 PM

            Bitlocker can use keys that are local only, but the default for home editions of Windows was to use the online account to back it up.

            'Happily' is also a stretch, as they really don't have a choice if served a valid court order.

            If you want encryption that is safe from the US government, keys need to be stored in your head. Anything physical is subject to court orders.

          • john_strinlai

            today at 4:51 PM

            for enterprises, where this doesn't really matter, bitlocker is great.

            • dijit

              today at 4:59 PM

              if by "great" you really mean "fine".

              It's still brittle, awkward and puzzlingly awful UX despite being the literal standard for the platform.

              Compare it to any of the actively maintained alternatives, Filevault for MacOS (which is wonderful and never sends your key to be kept somewhere else) or LUKS on Linux.. heck, even Veracrypt is actually easier to understand and more robust.

              • john_strinlai

                today at 5:02 PM

                >if by "great" you really mean "fine".

                no, i mean great.

                managing a fleet of 100+ laptops with bitlocker is a breeze. its so seemless that the users don't even realize its enabled (i.e. no UX issues, at all).

                on the other hand, i am not managing 100+ laptops that use veracrypt. sounds absolutely awful. i've never managed an apple fleet, so i can't speak to that, and will take your word on it.

                for personal use, i do not recommend bitlocker (or windows, really), but for already-windows enterprises? absolutely

                • dijit

                  today at 5:17 PM

                  Flicking a button to turn something on is not what I'm talking about, that's normally the easy part of any setup, and I judge people harshly who only take that aspect of something into consideration when discussing systems.

                  Brittle is what happens when you haven't logged on to the machine in 60 days, trust with AD is broken, TPM has a glitch and wipes the in device key and forces you into recovery... or god forbid you service the laptop and now you have to enter recovery mode.

                  Then you're in a nightmare, trying to give someone a super long passphrase over the phone is a not-too-uncommon occurance.

                  That's assuming you have a good policy for storing the recovery keys. Too loose and they're handed out to everyone, sort of defeating the purpose: too strict and you need the IT department (or specific members), and its still predicated on the notion that you have a policy for it... Given that Admins are a dying breed... I don't think this is workable.

                  If you compare with Filevault on MacOS: which tracks the credentials of the logged in user; there's no "issue" if the device loses trust because ultimately you always use the real unlock key: not something cached in a "secure storage".

                  • bri3d

                    today at 5:28 PM

                    Having dealt with FileVault in this context, it's also frustrating; it's really common to have it fail to follow the logged-in user's credentials, and if you use any kind of federated login, you will frequently get users with FileVault passwords that are either ahead of or behind their system login password.

                    I think both approaches are valid trade-offs and I think that the default Secure Boot BitLocker configuration, for all its architectural tradeoffs, can probably be credited for an enormous amount of data loss mitigation originating from used hard drives alone.

                  • john_strinlai

                    today at 5:27 PM

                    maybe i am missing something, but how did veracrypt solve all of the admin and policy issues you’re bringing up? (specifically for large enterprise fleets)

                    • dijit

                      today at 5:31 PM

                      If you use your key every day you tend not to forget it.

                      If I as an admin give you your key: it is “leaked” effectively.

                      • john_strinlai

                        today at 5:33 PM

                        >If you use your key every day you tend not to forget it.

                        hoping users don’t forget their password is a very weak policy.

                        specifically, the policy and admin points you brought up above, how does veracrypt solve them?

                      • dcrazy

                        today at 5:38 PM

                        Have you never gone on vacation and forgotten your daily-use password upon return?

                • akerl_

                  today at 5:05 PM

                  Managing an Apple fleet is similarly fine, and that includes using any of the MDM tooling that also does key escrow on enterprise Filevault devices.

              • dcrazy

                today at 5:33 PM

                FileVault absolutely has an optional iCloud Keychain escrow. That’s how the “unlock with Apple Account” feature works. Apple doesn’t have the keys for iCloud Keychain, but it is still stored in iCloud.

              • j16sdiz

                today at 5:19 PM

                > Filevault for MacOS (which is wonderful and never sends your key to be kept somewhere else)

                Did you read the documentation?

                https://support.apple.com/guide/mac-help/protect-data-on-you...

                "iCloud account: Click “Allow my iCloud account to unlock my disk” if you already use iCloud. Click “Set up my iCloud account to reset my password” if you don’t already use iCloud."

                https://developer.apple.com/documentation/devicemanagement/f...

                "FileVault Full Disk Encryption (FDE) recovery keys are, by default, sent to Apple if the user requests them. Only one payload of this type is allowed per system."

                • dijit

                  today at 5:22 PM

                  Can.

                  If you click "Allow my iCloud account to unlock my disk", your recovery key is escrowed to Apple, tied to your Apple Account.

                  If you don't select that option it never does.

                  I should have said "without your explicit permission", but I assumed we were all adults and understood that.

                  The main point is that it's using your account password to unlock, the recovery key is for if you forget your account password.

                  • dcrazy

                    today at 5:35 PM

                    No, you were just plain wrong. You said “never”, when in reality BitLocker and FileVault both have optional escrow.

              • Arainach

                today at 5:09 PM

                Veracrypt is more difficult to set up - whether on one machine or a fleet. Bitlocker is a few buttons in the UI, configurable via Group Policy, and so much more.

                What is brittle or awkward?

                • dijit

                  today at 5:12 PM

                  "PLEASE ENTER YOUR BITLOCKER RECOVERY KEY"

                  Where is it?

                  A) Uploaded to microsoft

                  B) Somewhere in EntraID?

                  C) Somewhere in our onprem AD?

                  D) Written down on a scrap of paper when I set up the laptop

                  the fact that they never ask for the passphrase is a weakness of the system. Because now you have an extremely difficult situation as soon as you're off the happy path.

                  It's also like 64 characters alphanumeric with no capability to copy/paste.

                  Compare it to Vera/Filevault where the access key is the users passphrase. In MacOS it's literally your account password, which follows along with your in-OS account credentials.

          • philipallstar

            today at 4:51 PM

            Does that mean it's not the de facto standard on Windows?

          • naturalmovement

            today at 4:58 PM

            So exactly like FileVault?

• dist-epoch

  today at 5:04 PM

  Both Intel/AMD CPUs produced in the last 5 years or so support full transparent (to the OS) memory encryption. So cold boot attacks are a thing of the past if you enable this feature (it's typically disabled because it reduces RAM speed by about 0.5%).

  • tredre3

    today at 6:21 PM

    The impact on performance is more along the lines of 1-2% on AMD (though it likely varies by generation (I did extensive benchmarking on Renoir wrt throughput/latency/gpu). But yes small enough to be insignificant unless you run LLMs or game on the iGPU. I imagine that it also uses marginally more power.

    AMD also has a second encryption mode where the OS decides what gets transparently encrypted, it doesn't have to be everything. But that mode is poorly documented (or at least the documentation isn't accessible to peasants like me)

• crypttales

  today at 4:41 PM

  [dead]

But if you do this, don't you have to enter two passwords each time you wake? One for LUKS, one for the system login?

• polotics

  today at 6:21 PM

  Well yes and I don't see how this can be avoided.

This is one of those regressions that's easy to miss because everything still "works." Security bugs often don't announce themselves.

• IngoBlechschmid

  today at 4:56 PM

  Right! Which is why integration tests for these kinds of features are all the more important.

  It was also fun to write, and enabled git-bisecting to isolate the specific kernel refactoring which introduced this bug: https://github.com/NixOS/nixpkgs/pull/532499

I don't have to re-enter my boot password after Sleep, so obviously the encryption key is still in memory.

• wrs

  today at 4:23 PM

  Obviously your distro isn’t using cryptsetup-luksSuspend.

  • unethical_ban

    today at 4:59 PM

    Correct.

    The point being made is: If one isn't re-entering their passphrase after suspend, how are they surprised that the encryption keys are somewhere in memory during suspend?

    edit: I see now that the prompt was being given and the keys still resided in memory.

    • ksbd-pls-finish

      today at 5:03 PM

      Because debian users with luks-suspend have to re-enter their boot password after sleep.

    • weaksauce

      today at 5:06 PM

      > The point being made is: If one isn't re-entering their passphrase after suspend, how are they surprised that the encryption keys are somewhere in memory during suspend?

      If that was the case for the people using the debian extra secure extension that should have wiped the memory clean then someone would have found this bug much earlier than two years. Their password was required to be re-entered even though the key was still in memory somewhere.

    • akerl_

      today at 5:07 PM

      The reason this bug is unexpected is that the user is expecting to have to enter their password (because they expect the key to be wiped on suspend), and then _they are_ asked for their password. But there was a copy of the key elsewhere in kernel memory that was never cleared.

      • unethical_ban

        today at 6:13 PM

        Ah, my bad. Yes, if the user was being presented with the prompt on wake, I see the problem.

        I have never had that setup so I was confused.

    • killerstorm

      today at 5:19 PM

      Well, potentially a key might be stored in TPM. But I don't think that's better

      • joshuaissac

        today at 6:18 PM

        I would hope that it is harder to get into the TPM than into the RAM.

I don't think this bothers me.

The only reason that I do the disk encryption is so that I don't have to worry about people going through my laptop to steal tax documents and/or credit card stuff when I sell the laptop. I of course also wipe the laptop too, but I figure that if the data is encrypted at the drive level then there's very little risk of anyone being able to use some kind of forensics tool and recover data.

I am far from a security expert, but from the number of "we missed a single line C check across files during refactoring" critical security bugs discovered on a regular basis these days, the whole premise of a "giant secure open source C codebase" seems questionable. It is not specific to C of course, but invariants are arguably even harder to enforce and track consistently (esp under changes to code) in C. Unsure if FP with invariants encoded in types is a practically feasible scalable solution either. Model checking? [LLM] fuzzing? Fewer primitives with clear boundaries? Is that how seLinux was "checked"?

• fsddfsdfssdf

  today at 5:45 PM

  While I can see the shortcomings of C and generally don't recommend it for new projects I don't see this particular bug as a good example of something Rust's borrow checker or some other language's type system will catch. I don't think even static analyzers can catch this.

  It's basically something like this:

  original: DoTheThing()

  new: DoTheThingSlightlyDifferentButKeepMyCredentialsAlive()

  fix: DoTheThingSlightlyDifferentButDoInFactNOTKeepMyCredentialsAlive()

  In my experience a substantial portion of gnarly bugs come down to a violation of a high-level system invariant and those do not strike me as something that can be automated. Even with something like Lean you can prove your program satisfies certain properties but you need to have thought about those properties in the first place. The proof doesn't discover the invariant for you.

  If you'd had thought about the relevant security property you could have written a regression test for it which is not hard. IMO the really hard part isn't expressing the implementation safely, but it's the realization that this was a property the implementation needed to preserve.

  • bbminner

    today at 6:18 PM

    I agree re Rust vs C - this is not (only) a language issue. What would (roughly) the invariant be here?

    In another thread comment below i argue that maybe the system (OS) itself is so complex that it lacks clear contract / the contract evolves too quickly over time (as other parts of the code need to change the given piece of code to extend it to their use case) and that defies clear encoding?

    Or we lack easy enough means to describe specs? I tried reading jepsen spec earlier today and despite it being an "integration test" of sorts, it is far from "simple".

    Can an entire OS or a system of comparable complexity be decomposed into objects simple enough that their entire intended behavior (with all edge cases) can be explained in a paragraph of human text + half a screen of dense behavioral "spec" - if i do X and do Y, Z should come out / hold _no matter what happens in-between_. Or that's what asserts + fuzzing is effectively supposed to do? Is there a clear distinction between invalid input and failed invariant in typical C code? I guess error code vs seg fault?

  • estebank

    today at 6:01 PM

    This is in effect a state machine, and when you have a type system more complex than C's you can encode state transitions in the type system (either by having state transitions explicitly return a new return type or by using sum types). You still need to architect the system to encode the invariants in types. No language will fix all logic bugs for free. But you can leverage language features to reduce their number.

    • fsddfsdfssdf

      today at 6:10 PM

      > You still need to architect the system to encode the invariants in types.

      That's the problem though, right? If it's pointed out we all agree the "do not keep credentials alive" is a property that should hold and we can leverage whatever the environment offers to help preserve it. I fully agree modern languages have amazing support for this, but in C you can still run tests. Let's just say I don't think the language's inability to express logic of this kind held all those involved back from testing for it. I personally find "we just didn't think of it" much more likely.

      That said, I am not a fan of C and recommend leveraging whatever fantastic modern tooling is available to you.

• pjdesno

  today at 6:01 PM

  To translate to Rust, it would have been "we missed a single line Rust check"...

  This is a bug involving intersecting concerns and a deficit of cross-domain knowledge. It probably would have been the same in Lisp or assembly language.

• WhitneyLand

  today at 5:40 PM

  The premise of a secure open codebase is fine.

  The problem is being more auditable does not automatically make it more audited.

  There have to be enough people with skill taking enough time to work on it.

  • pixl97

    today at 5:49 PM

    If you think open source is bad, wait till you see enterprise code. I'm talking full auth bypass due to the stupidest crap. You can do that in any language if you have fools working on the code base.

    • danudey

      today at 5:59 PM

      Even security code. Fortinet, a vendor whose entire thing is security for your network, is consistently getting caught out with default passwords, backdoors, etc.

      https://community.spiceworks.com/t/hard-coded-password-backd...

      This sort of thing leads to every kind of exploit, like

      https://www.linkedin.com/pulse/half-worlds-fortinet-firewall...

    • 620gelato

      today at 6:01 PM

      I explicitly make sure services I lead have Integration tests in CI pipeline to validate the "negative paths" against all APIs with missing, invalid, un-authorised identities, expired, un-authenticated tokens. Of course that still doesn't cover every surface, but even that gets sideways glances from some folks who think we should just test happy paths and why we're testing for access controls in Integration tests.

• russdill

  today at 5:44 PM

  The lesson here is that if a feature (at a minimum) does not have a associated test case, it is not actually a feature.

  • fsddfsdfssdf

    today at 5:58 PM

    Yes, I agree. I find the addition of the regression test the true long-term fix. The code is just an opaque incantation that may or may not preserve some property we find worth preserving and we have no way of knowing it keeps preserving it over time as other parts of the system change.

    The test actually proves it and while it too can change it has more staying power because it's expressed at a higher level of abstraction ("random arcane weird C shit" in the case of code versus "does this property hold" in the case of a regression test).

• moritzwarhier

  today at 5:21 PM

  The whole premise of a "giant secure open source C codebase" seems questionable

  Because code review is sometimes not much different from an idealized version of the halting problem, where you would have access to a formalized version of a specification.

  In other words, there is no strict definition of what is a security issue.

  • bbminner

    today at 6:05 PM

    On the other hand, it is (both halting and spec adherence) are checkable under compute and space constraints though? :) I'd say the biggest hurdle are means to describe the spec in way that is easy enough for a human to produce to make it feasible.

    Not a DB person either, but things like TLA+ seem very hard to write even with LLMs. Behavioral tests with an enumerable number of random paths to take (aka model checking - eg jepsen) seem more feasible. Although you can't check internal properties of the system (string `pass` or any of it's copies or parts are not held anywhere in memory at any point between lines A and B) unless we can check that two memory dumps are indistinguishable with different pass strings (assuming we abstracted away storage devices in a test environment).. Also not sure if it's "easy enough" to write such tests either.

    Maybe the reason is that OS domain objects / primitives are too complex and not "isolatable" enough / lack a clear contract at all? (Hence multi file refactorings that break invariants.)

• lazide

  today at 5:24 PM

  In open source, someone (many, many) someone’s can at least check.

  Closed source…..

  • Twirrim

    today at 5:36 PM

    Not sure why you're getting downvoted, this is the entire point of open source.

    Does such a bug exist in Windows? OSX? Who checks? If someone finds the key in memory, can they tell what conditions might be causing it and where?

    Their only recourse under those situations is to hand it off to the OS Vendor and trust that what they implement does solve the problem, and trust that it wasn't a deliberate back-door that is now being replaced by another back-door.

    • charcircuit

      today at 5:40 PM

      Security researchers find security bugs in closed source operating systems all of the time.

      • lazide

        today at 5:45 PM

        Yup, it’s just harder to know for sure.

        • pixl97

          today at 5:51 PM

          Oh, and large companies quite often fix these horrific issues silently, especially in online services where the customer can't diff bins. We're talking auth bypasses and RCE's that you'll never know about.

• deepsun

  today at 6:01 PM

  "Million eyeballs" argument was always kinda meh.

On my laptop with Fedora I just configured Linux to hibernate to disk after 15 minutes of suspend. Powering memory off ensures that bugs like this Debian-specific would not matter.

Plus what Debian extension to Linux tooling does although nice in theory, but in practice if one really worries about cold-boot attacks, then all keys and important documents has to be wiped out from memory, not only LUKS keys.

So hibernating is really the only proper way to protect against cold boot.

• IngoBlechschmid

  today at 5:20 PM

  > So hibernating is really the only proper way to protect against cold boot.

  I agree; or resurrecting FridgeLock: https://www.sec.in.tum.de/i20/publications/fridgelock-preven...

• killerstorm

  today at 5:16 PM

  Hmm, where does it get a key to decrypt memory on resume?

  AFAIK it's practical only if you make use of TPM. And if you do, you're basically at mercy of TPM.

  • teravor

    today at 5:16 PM

        > where does it get a key to decrypt memory on resume?
    

    you enter it...

on the subject of encryption keys and memory there is something you can do:

- if your CPU supports it, enable memory encryption.

- if your TPM module supports this look for MemoryOverwriteRequestControl & MemoryOverwriteRequestControlLock (/sys/firmware/efi/efivars/) and toggle them. make sure that your computer always reboots and never powers off. memory will always be wiped on boot.

• someothherguyy

  today at 5:40 PM

  https://trustedcomputinggroup.org/wp-content/uploads/TCG-PC-...

> Except that, for more than two years, the encryption key remained resident in memory across suspend, leaving it there for the taking by anyone who seized the still-powered laptop.

I don't get it. Obviously, the laptop is locked when it resumes, how is that key "for the taking by anyone"? I'm not saying it is impossible to read out RAM from a locked laptop, but surely not by "anyone".

• nicce

  today at 4:55 PM

  Anyone with physical access. I think it is understandable from the phrase.

  There is a common misconception about how lock-screens in general work - they usually just prevents using the current hardware and software as it is to access the current OS. But the disk encryption is the main thing that prevents modification and other kind of access to actual data. And if the disk encryption key is lying in the memory, then effectively, the disk encryption is bypassed if someone can access the machine physically and assuming that there are no sufficient tampering protections in place for that machine.

  • acdha

    today at 5:01 PM

    Anyone with physical access, significant tools, and experience. The FBI has people who can pull data out of memory after freezing the RAM but the average laptop thief doesn’t so how serious this is depends significantly on your threat model. If you’re not a major criminal, bitcoin whale, or intelligence target this is almost certainly academic.

    • deng

      today at 5:08 PM

      > If you’re not a major criminal, bitcoin whale, or intelligence target this is almost certainly academic.

      Thanks, that's what I thought.

  • deng

    today at 4:57 PM

    > Anyone with physical access. I think it is understandable from the phrase.

    Sorry, I'm probably dense, I still don't get it. You steal a laptop, you open it, the screen is locked with a password/fingerprint whatever. How do you read out the RAM from that laptop?

    • IngoBlechschmid

      today at 5:01 PM

      Several options. One is you restart and boot from a live system where you are root, and then dump all memory. This is described in the paper with the witty title "Lest We Remember: Cold Boot Attacks on Encryption Keys":

      https://www.usenix.org/legacy/event/sec08/tech/full_papers/h...

      Other options: DMA attacks. Also you never know what the Intel Management Engine hidden in your computer is doing. It's running a version of Minix you don't have any control over, and it has full access to memory.

    • john_strinlai

      today at 4:59 PM

      >How do you read out the RAM from that laptop?

      the term to look up is "cold boot attack" (https://en.wikipedia.org/wiki/Cold_boot_attack).

      tons of cool live demonstrations of how it works on youtube if you've got the 20-40 minutes to spare

      • deng

        today at 5:03 PM

        Still, this is a pretty crazy definition of "anyone".

• jakewins

  today at 4:58 PM

  There are attacks that allow dumping RAM if the device is powered on though and you have physical access. Depending on config it may be very easy (just plug in a dumper over Thunderbolt on USB C and do direct memory access) or hard (freeze and swap physical RAM to an unlocked machine).. but the idea was defense-in-depth here; a well configured device should both be hard to dump RAM on and it should not give encryption keys if an attacker succeeds.

• today at 4:57 PM

• saidnooneever

  today at 5:12 PM

  you dump the physical memory, then decrypt the disk offline

It's because of vulnerabilities like this that I enable Intel's "total memory encryption" feature. No plaintext leaves the CPU package. DIMM swap attacks become useless. Moreover, it's basically free: the cryptography happens directly in the memory controller, in hardware, inline with the bus transactions the CPU is doing anyway.

• fsckboy

  today at 6:16 PM

  I don't see how that solves this problem. there is a string in memory that gets saved on suspend. that string when read by the CPU has the same properties it had before. if the CPU is using rot-13, the string is still rot-13 and the attacker doesn't need to spend the compute needed to crack rot-13, the CPU will simply do that as normal.

[flagged]

• palata

  today at 4:10 PM

  And I don't use GUIs, but it doesn't mean I have to be a jerk to people who are happy when their GUI gets better :-).

  • panny

    today at 4:16 PM

    Suggesting I'm an exotic animal for being budget and environmentally friendly is being a jerk too.

    • today at 4:27 PM

• ekunazanu

  today at 4:11 PM

  > That's a you problem. I shutdown my machine when I'm not using it.

  "We designed the antennas correctly, you're holding the phone the wrong way."

  • adontz

    today at 4:12 PM

    It's not a good analogy. Something is still on in suspend. Good you can control Linux kernel, but what about all other chips which may be an attack vector?

  • 1718627440

    today at 4:22 PM

    Except shutting down and hibernate are two actions the user can literally select from the same menu.

• bwat49

  today at 4:09 PM

  I shutdown mine too but only because suspend is still a crapshoot on linux

  • jchw

    today at 4:34 PM

    There will always be more suspend/resume bugs to work through. It varies a lot per device. I feel it's necessary to paint the picture for people who are curious what it means for it to be a crapshoot, so indulge me while I share my experiences.

    For work I have a ThinkPad T16 Gen 4 with the newer AMD gfx1151 iGPU. Works great. I have yet to witness any issues with suspend/resume. I suspect this is the case because it is running Ubuntu with Lenovo's own support package. Theoretically, from firmware to kernel, this is all tested and validated by Lenovo, like what certainly happens with every Windows laptop and all of the components that go into them.

    I also have a gen 1 Framework 16. I have seen it crash on suspend, but it is pretty rare, so I've just shrugged it off for now. It would be hard to debug, I don't see it every month despite using the thing every day.

    All of my desktops currently have perfectly reliable suspend resume, you can slam it all day and all night. The last time I ran into issues was a use-after-free issue in AMDGPU. Pretty alarming, although to be clear it never hit any LTS or vendor kernels that I am aware of. I hit it because I prefer to run the latest kernel on my personal machines.

    I have certainly owned laptops where suspend basically didn't work, or it would not stay suspended. I think this mainly went away when I started specifically picking laptops for Linux support.

    For Intel iGPUs and dGPUs, the track record has been flawless for me. I have a few of the new Battlemage cards that default to the xe kernel driver and those have been working very well as expected. So that's nice.

    I don't think this situation will be fixed until more hardware vendors are taking part in validating their stuff on desktop Linux and keeping track of the kernels. The current Linux model seems to be just dealing with whatever the vendors crap out for Windows, often full of weird ACPI behaviors and buggy firmware. It's not to say that the fault of the problems don't often lie with code in the Linux kernel, but they do not seem to wish to be bug-compatible with Windows and I think that is perfectly reasonable, so for problems that come from essentially broken firmware, it simply is going to need vendors to actually fix their shit.

    (And that includes AMD. The drivers are good in some regards, but it's hard to ignore AMD's stability issues even still. At this rate, more of the long outstanding AMD driver issues will get resolved by Claude than AMD engineers... Like with Panel Self Refresh on 7040 iGPU, apparently.)

• today at 4:10 PM

• codedokode

  today at 4:15 PM

  I am too lazy for that, and I hate that after boot you need to launch everything again.

  • IngoBlechschmid

    today at 4:28 PM

    Suspend to (encrypted) swap might be a good middle ground between you and grandparent. Suspend to memory will (at best) protect your LUKS volume key, but other sensitive data remains.

    A couple of years ago, three security researchers from the TU Munich implemented a prototype for also encrypting (most) parts of the memory just before suspend, to address this limitation; but as far as I know, it was not upstreamed or developed further: https://www.sec.in.tum.de/i20/publications/fridgelock-preven...

  • 1718627440

    today at 4:21 PM

    You can usually change that in the settings of the Desktop environment.

    • codedokode

      today at 4:24 PM

      There is no universal support for restoring state between the apps. For example, Terminal won't run the scripts that were running, the browser will not automatically restore the pages etc, some apps might not launch or launch with wrong state.

      Gnome desktop environment cannot even remember the position and size of console windows, you are expecting too much.

Definitely not a symptom of Linux being a hodgepodge of code thrown together from a thousand different sources and no one person could tell you how it all fits.

• cevn

  today at 4:34 PM

  Bugs happen in all code. The difference is, anyone can fix stuff in open source. Closed source bugs are out of control and must be worked around. Usually by switching to OSS

• steve918

  today at 4:30 PM

  I wonder if you think other OSes are any different?

  TempleOS is the only thing that comes to mind that doesn't fit your description and it's not practically useful.

  Any sufficiently large codebase is a mix of ideas and concepts implemented by different people with different priorities over a large timespan and if you can fit the entire thing in your head it's not very interesting or complex.

  • IngoBlechschmid

    today at 4:53 PM

    Qubes OS, the Linux distribution aspiring to offer a reasonably secure operating system, pioneering a "every app runs in a virtual machine" approach in the Linux laptop/desktop space, tracks this at the following issue:

    https://github.com/QubesOS/qubes-issues/issues/2890

    • saidnooneever

      today at 5:20 PM

      QubesOS is Xen based. Not Linux.

  • naturalmovement

    today at 4:35 PM

    The *BSDs, Mac, and Windows all keep critical code in the same tree as the OS.

    Something like disk encryption would be immediately visible.

    So you don't have this mess of 80 different distros with 60 different versions of systemd, 20 that don't use it, a million kernel versions and it's all thrown together in a Costco-sized trash bag and we call the output "Linux".

    • yaris

      today at 4:45 PM

      In my experience any software system (not just operating system) after crossing a certain limit on complexity and age looks exactly as hodgepodge of code pieces thrown together, sometimes from different sources even if developed by one org. All major OSs have long crossed those limits, I believe.

    • brainwad

      today at 4:59 PM

      Windows for ages did not really keep all the code in one repo. There were like a dozen parallel repos for e.g. the shell, kernel, IE, etc. Also every feature was developed on team-level branches; integrating all those branches often caused unexpected bugs.

• stackghost

  today at 4:30 PM

  Of course it's (indirectly) a symptom of that.

  What's the alternative? Proprietary closed-source operating systems owned by corps who can be compelled to insert covert backdoors?

  If BSD was as popular as Linux it would have the exact same problems.

• today at 4:43 PM

• dist-epoch

  today at 5:06 PM

  "Mythos, find me a bug in LUKS. I know there is one in there".

  • today at 5:31 PM