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Yes, relevant in case of a lost device: "Motivated by Windows 11’s push to use the TPM for even more applications, we apply the vulnerability to Microsoft BitL

Yes, relevant in case of a lost device: "Motivated by Windows 11’s push to use the TPM for even more applications, we apply the vulnerability to Microsoft BitLocker and show the first fTPM-based attack against the popular Full Disk Encryption solution. BitLocker’s default TPM-only strategy manages – without any changes to the user experience – to swiftly step up a user’s security in the face of a lost or stolen device. However, as our work complements the established at- tacks against dTPMs with an even more potent attack against AMD fTPMs, a TPM-only configuration lulls a non-technical user with high protection needs into a false sense of security." "Users who fear a physical attacker with reasonable resources should opt for a TPM and PIN configuration. When BitLocker identifies that the underlying TPM is an fTPM, users should be urged to turn their PIN into a passphrase."

goolz 3y ago
Does this line imply then it is mostly a concern for Windows users? I don't mind only using Linux, it is Best in Slot for most tasks anyways.
- creshal 3y ago
  ChromeOS also heavily relies on TPM for disk encryption, and unlike Windows doesn't even give you the option of adding a passphrase or pin on top of it. And there's probably some large enterprises that use regular Linux desktops with LUKS/Btrfs/ZFS encryption in TPM only mode, to match their Windows setups. Systemd e.g. added systemd-cryptenroll with ergonomics comparable to Windows' Bitlocker enrollment.
- dfox 3y ago
  Typical Linux installation will not rely on TPM in any way. But if you use systemd-cryptenroll to provide BitLocker-like UX for FDE then the concerns are mostly same.
- dhx 3y ago
  It could also be a concern for Linux users if they have configured their system to use systemd-cryptenroll (even with --tpm2-with-pin=yes or --fido2-with-client-pin=yes). The user is not asked for a secure passphrase in addition to having a TPM present. The user is just asked for a short PIN that is provided to the TPM2 or FIDO2 device and the device is not meant to return the secret without a valid PIN being provided.
  - hnj2 3y ago
    There is actually an interesting point regarding TPM+PIN and systemd-cryptenroll: The data sealed in the TPM can directly be used to decrypt the disk (it is base64 encoded and used as a passphrase for a luks key slot). The PIN is only used to authenticate the TPM's unsealing of the data. In contrast, the unsealed BitLocker data still needs to be decrypted with the pin to get to the VMK. When our attack is successfully executed on a target, this means that TPM+PIN is broken on systemd-cryptenroll, and as secure as PIN-only with the same PIN on BitLocker.
- dathinab 3y ago
  if Linux full disk encryption would have a more user friendly UX a lot of Linux users would probably use that too its a very convenient feature through is not convenient to setup and a lot of Linux users never trusted it to be secure, i. e. a lot of people expected an attack like this sooner or later
  - folmar 3y ago
    The current state of userfriendly is quite good. In Ubuntu it's just a checkbox in the installer and input a passphrase.
    - dathinab 3y ago
      yes and it does use the TPM and is affected by this attack ;=) at least the recent ubuntu versions when using the default full disk encryption setup do setup decryption using TPM you still need an additional password as without you would e.g. lose access to your data if you change some hardware, you motherboard brakes or depending on how they set it up you also need the password after kernel upgrades etc. but the vulnerability allow someone with hardware access to access all your data by booting their code but messing with the TPM in a way where it still measures as if it's was booting your code
    - Rimintil 3y ago
      The passphrase is what makes it a poor user experience. Many people simply need an encrypted disk that you can't boot offline and not the boot-time PIN/passphrase (which Microsoft abandoned as the default in Windows 8, I believe, again due to UX).

goolz 3y ago

Does this line imply then it is mostly a concern for Windows users? I don't mind only using Linux, it is Best in Slot for most tasks anyways.

creshal 3y ago
ChromeOS also heavily relies on TPM for disk encryption, and unlike Windows doesn't even give you the option of adding a passphrase or pin on top of it. And there's probably some large enterprises that use regular Linux desktops with LUKS/Btrfs/ZFS encryption in TPM only mode, to match their Windows setups. Systemd e.g. added systemd-cryptenroll with ergonomics comparable to Windows' Bitlocker enrollment.
dfox 3y ago
Typical Linux installation will not rely on TPM in any way. But if you use systemd-cryptenroll to provide BitLocker-like UX for FDE then the concerns are mostly same.
dhx 3y ago
It could also be a concern for Linux users if they have configured their system to use systemd-cryptenroll (even with --tpm2-with-pin=yes or --fido2-with-client-pin=yes). The user is not asked for a secure passphrase in addition to having a TPM present. The user is just asked for a short PIN that is provided to the TPM2 or FIDO2 device and the device is not meant to return the secret without a valid PIN being provided.
- hnj2 3y ago
  There is actually an interesting point regarding TPM+PIN and systemd-cryptenroll: The data sealed in the TPM can directly be used to decrypt the disk (it is base64 encoded and used as a passphrase for a luks key slot). The PIN is only used to authenticate the TPM's unsealing of the data. In contrast, the unsealed BitLocker data still needs to be decrypted with the pin to get to the VMK. When our attack is successfully executed on a target, this means that TPM+PIN is broken on systemd-cryptenroll, and as secure as PIN-only with the same PIN on BitLocker.
dathinab 3y ago
if Linux full disk encryption would have a more user friendly UX a lot of Linux users would probably use that too its a very convenient feature through is not convenient to setup and a lot of Linux users never trusted it to be secure, i. e. a lot of people expected an attack like this sooner or later
- folmar 3y ago
  The current state of userfriendly is quite good. In Ubuntu it's just a checkbox in the installer and input a passphrase.
  - dathinab 3y ago
    yes and it does use the TPM and is affected by this attack ;=) at least the recent ubuntu versions when using the default full disk encryption setup do setup decryption using TPM you still need an additional password as without you would e.g. lose access to your data if you change some hardware, you motherboard brakes or depending on how they set it up you also need the password after kernel upgrades etc. but the vulnerability allow someone with hardware access to access all your data by booting their code but messing with the TPM in a way where it still measures as if it's was booting your code
  - Rimintil 3y ago
    The passphrase is what makes it a poor user experience. Many people simply need an encrypted disk that you can't boot offline and not the boot-time PIN/passphrase (which Microsoft abandoned as the default in Windows 8, I believe, again due to UX).