An attacker with physical access can abruptly restart the device and dump RAM, as analysis of this memory may reveal FVEK keys from recently running Windows instances, compromising data encryption.

The effectiveness of this attack is, however, limited because the data stored in RAM degrades rapidly after the power is cut off.

  • BaroqueInMind
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    2 days ago

    This exploit requires physical access, and if you have physical access, anything is possible. Secure your shit better.

    • stoy@lemmy.zip
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      2 days ago

      Bitlocker is designed to aid against phyiscal attacks, so physical access is a given.

      • sus@programming.dev
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        2 days ago

        the best you can ever do is make physical attacks more inconvenient, and it succeeds at that.

        Here’s another “critical vulnerability”: the attacker can insert a physical device to intercept all keystrokes, and steal the key whenever the user enters it. A hidden camera can also accomplish this

    • fmstrat@lemmy.nowsci.com
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      1 day ago

      Physical access to a running device, for clarity.

      Edit: Unless you use a TPM with no pin/password, which is dumb.

      • narc0tic_bird@lemm.ee
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        2 days ago

        It doesn’t already have to be running. BitLocker retrieves its keys from TPM by default, so just booting a device will place the keys in memory.

        To minimize downtime, abruptly restart the target system during the Windows boot process, specifically before the login screen appears, as this approach has proven effective in scenarios involving the retrieval of Full Volume Encryption Keys (FVEKs).

        By kernel-level debugging with WinDbg, the researcher observed BitLocker operations during the Windows boot process, which revealed that while Microsoft attempts to erase encryption keys using functions like SymCryptSessionDestroy, some keys persist on the heap, potentially due to incomplete key destruction mechanisms.

        • fmstrat@lemmy.nowsci.com
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          2 days ago

          You’re misreading that, I’m afraid. Direct from the researcher:

          This can be done in a variety of ways but the goal is to minimize how much time the computer is completely powered off. In my experience I have had the most success restarting the system while Windows is loading but before the login screen has appeared, at least in the case of finding FVEK keys.

          “While Windows is loading” … You must restart after the BitLocker password has been entered and the key is stored in RAM, that’s how this exploit works. He had the best luck at that point durong boot, but it could be attempted at any time when RAM is powered and BitLocker is already unlocked. A shutdown or hibernated system is not vulnerable.

          • narc0tic_bird@lemm.ee
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            1 day ago

            A lot of BitLocker setups unlock using just TPM though, which was my point. No password/PIN needs to be entered at boot time to unlock it, it uses the TPM to unlock. This is the default setup that many companies use. Password/PIN unlock is completely optional.

            I’m not misreading that.

            • fmstrat@lemmy.nowsci.com
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              1 day ago

              Not the default at any company I’ve been at. What’s the point of encryption if it’s unlocked right away? Whoever’s doing that deserves this exploit. However, since that’s factually correct I’ll edit my original comment to add in:

              unless you use a TPM with no pin/password, which is dumb

              • sugar_in_your_tea@sh.itjust.works
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                1 day ago

                Exactly.

                I don’t use BitLocker, but I do use FDE on Linux, and I use a password at the bootloader level. Why would I bother with all the downsides of FDE if it isn’t actually secured by a password?

            • Railcar8095@lemm.ee
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              1 day ago

              If the computer doesn’t password protection and the attacker has physical access… They can just copy the data, why care about the keys?

              I think that’s already a worst case scenario.

              • narc0tic_bird@lemm.ee
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                1 day ago

                The user still has to login to their user account. The assumption is that the Windows login is secure so BitLocker can decrypt using TPM and an attacker still won’t have access to the data without being able to log in.

                This article obviously shows a method how an attacker can potentially still get access to the data without logging in.