A newly found security flaw in Ubuntu could allow attackers with physical access to bypass full disk encryption. Learn how the attack works.
  • fmstrat@lemmy.nowsci.comEnglish
    32·
    1 day ago

    I’m confused.

    Initramfs is unencrypted in /boot when using LUKS with RAID. It has to be, right?

    The attacker uses a debug shell to modify the unencrypted boot, so the next time you boot and type your LUKS password, they can gain access.

    This doesn’t line up with your comment?

      • fmstrat@lemmy.nowsci.comEnglish
        52·
        1 day ago

        You always “boot something that is unencrypted.” You then “mount” the encrypted volumes and load the OS.

        This is how people can put an SSH server (dropbear) in initramfs so they can unlock remotely.

        The attack is to initramfs, not the encrypted layer.

        The order’ish:

        • Boot
        • Initramfs loads, gives you the LUKS prompt
        • Initramfs decrypts/mounts OS
        • OS loads
          • fmstrat@lemmy.nowsci.comEnglish
            31·
            21 hours ago

            But… your original comment is just… wrong?

            This isn’t a critical security flaw unless you have the worst partition scheme on your encrypted volumes imaginable.

            The default LUKS partition scheme is vulnerable.

            It’s not even a process flaw at that point, just “possible”.

            There is a successful POC, it is a flaw.

            you can compromise disks once encrypted because everything is happening in an in-memory boot process.

            This is not just in-memory. This is modifying the unencrypted part of initramfs on disk. Powering off the machine does not remove the exploit.