Breaking Bitlocker – Bypassing the Windows Disk Encryption [video] • Hacker News Board

Re: Breaking Bitlocker – Bypassing the Windows Disk Encryption [video]

#71

Post by veeti » Mon, Feb 05, 2024, 9:02 AM UTC

_cenw wrote: post #68

H8crilA wrote: post #25

Earlier quoted context omitted.

You use a Diffie-Hellman key exchange, signed by a cert stored in the CPU on one side and verified by the TPM on the other. CPUs already have such secret certs inside of them, for example for Intels' SGX. But as you can read in the article linked by /u/osy, the TPM ecosystem is a victim of design by committee where such things as a threat model are not a thing. They were focused on building a "generic security soluti…

Or you use fTPM, the one inside your CPU, which is how most computers that run Windows 11 (without bypassing the restrictions) do it.

Unless you happen to have an fTPM that is permanently vulnerable to such attacks: https://www.amd.com/en/resources/product-security/bulletin/a...

Re: Breaking Bitlocker – Bypassing the Windows Disk Encryption [video]

#72

Post by osy » Mon, Feb 05, 2024, 11:36 PM UTC

mjg59 wrote: post #18

osy wrote: post #10

TPM is insecure against physical attacks by design: https://gist.github.com/osy/45e612345376a65c56d0678834535166 The only secure implementation is called D-RTM which requires a level of chip, OEM, and OS support that's not done in practice.

Not really? Encrypted sessions block the trivial attack of just watching the secret go across the bus. Pushing people to MITM attacks is already an improvement, and while generating initial trust in the TPM for that purpose isn't straightforward, it's not impossible. The almost universal implementation of TPM-backed secret management isn't secure against physical attack, but that's very different to "insecure by desi…

Yes really. The lack of any working implementation in production systems is an issue (D-RTM + encrypted sessions), something that Apple has done in an equivalent threat model since the iPhone 11. You can argue that "insecure by design" doesn't apply because there is a secure design in the abstract but the fact that nobody has adopted it in 20 years says something about the design itself.

It's _also_ insecure by design because in every deployed implementation (including with PIN), it is S-RTM meaning that _any_ UEFI driver vuln will compromise your TPM key. Yes, any UEFI vulnerability in its countless vendor drivers, USB stack, network stack, etc.

Re: Breaking Bitlocker – Bypassing the Windows Disk Encryption [video]

#73

Post by Avamander » Wed, Feb 07, 2024, 4:42 PM UTC

osy wrote: post #10

TPM is insecure against physical attacks by design: https://gist.github.com/osy/45e612345376a65c56d0678834535166 The only secure implementation is called D-RTM which requires a level of chip, OEM, and OS support that's not done in practice.

DTRM is offered with some Secured-Core machines that support Firmware Protection, is it not?

Re: Breaking Bitlocker – Bypassing the Windows Disk Encryption [video]

#74

Post by Dylan16807 » Wed, Feb 07, 2024, 7:35 PM UTC

dist-epoch wrote: post #9

matsz wrote: post #3

This is particularly interesting considering that TrueCrypt recommended migration to BitLocker as the main option for Windows: https://truecrypt.sourceforge.net/ IIRC Apple's version of TPM (Secure Enclave) should be immune to such attacks (since it's on the SoC, but I'm not sure whether the communication is encrypted or not), and the main data encryption method for GNU/Linux (LUKS) does not utilize TPM by default (m…

If you worry about someone sniffing your hardware buses, you should also worry about them intercepting your keyboard connection when you type the TrueCrypt password.

The problem is that they can sniff the bus at their convenience after grabbing the hardware and running. No need to hide a keylogger.