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Breaking Bitlocker – Bypassing the Windows Disk Encryption [video]

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

#11

Post by 0cf8612b2e1e »

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.

Does seem laughably easy to intercept the keyboard connection.

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

#13

Post by shawnz »

whyoh wrote: post #12

To decrypt a drive with a TPM-only key you just need to turn on the PC . So what's the big deal here? It's disappointing that TPM-only is the default for Bitlocker, but you can just use something else (pin/password, key file, ...).

These kinds of attacks aside, the intent is that you need to turn on the PC and then actually boot to the intended operating system, which is then protected with a login screen

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

#14

Post by mike_hock »

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.

I hope this attempt at shoving hardware DRM down our throats tanks just like the last one did.

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

#15

Post by ghostpepper »

aquova wrote: post #2

Very interesting video. For those who can't watch, he creates a PCB with a RPi Pico and some data pins which can sniff the BitLocker key as it's sent from the TPM chip back to the CPU. I was surprised to see that this was sent in plaintext, so although his board probably will only work for that particular motherboard, the method would be sound for other computers as well. I'll leave the comments about MS requiring TP…

It's a bit of a chicken-egg problem when the TPM is the root of trust for the entire system. Sure you can encrypt the data on the bus, but where do you store that key?

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

#16

Post by shawnz »

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.

Having a non-zero attack surface doesn't mean your security system provides "zero practical security". This is at best equally as hyperbolic as the vendors' own marketing claims that you are arguing against.

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

#17

Post by ale42 »

shawnz wrote: post #13
whyoh wrote: post #12

To decrypt a drive with a TPM-only key you just need to turn on the PC . So what's the big deal here? It's disappointing that TPM-only is the default for Bitlocker, but you can just use something else (pin/password, key file, ...).

These kinds of attacks aside, the intent is that you need to turn on the PC and then actually boot to the intended operating system, which is then protected with a login screen

Except that if you can sniff the encryption keys, you can tamper with the OS and for example remove the password...

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

#18

Post by mjg59 »

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 design". All the primitives to make this work reasonably are there, OS and firmware vendors just aren't using them.

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

#19

Post by mjg59 »

ghostpepper wrote: post #15
aquova wrote: post #2

Very interesting video. For those who can't watch, he creates a PCB with a RPi Pico and some data pins which can sniff the BitLocker key as it's sent from the TPM chip back to the CPU. I was surprised to see that this was sent in plaintext, so although his board probably will only work for that particular motherboard, the method would be sound for other computers as well. I'll leave the comments about MS requiring TP…

It's a bit of a chicken-egg problem when the TPM is the root of trust for the entire system. Sure you can encrypt the data on the bus, but where do you store that key?

You don't need to store that key anywhere, just like you don't need to store any keys to validate TLS connections.

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

#20

Post by northern-lights »

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.

There is nothing that is safe against physical attacks practically. You can always find a point where you can do a MITM attack as the communication channels between the TPM and anything else is almost always insecure.
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