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Comment by BobTheDestroyer | Hacker News Reader

Trezor has additional checks that aren't covered here. I'd really like to know how those were defeated. Especially:

>The bootloader verifies the firmware signature each time you connect your Trezor to a computer. Trezor Suite will only accept the device if the installed firmware is correctly signed by SatoshiLabs. If unofficial firmware has been installed, your device will flash a warning sign on its screen upon being connected to a computer.

https://trezor.io/learn/a/authenticate-model-one

There seems to be an element of user carelessness and naivety here. Anyone who follows Trevor's hardware verification checks surely needn't worry about these attacks.

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> All Trezor devices are distributed without firmware installed - you will need to install it during setup. This setup process will check if firmware is already installed on the device. If firmware is detected then the device should not be used. [...] The bootloader verifies the firmware signature each time you connect your Trezor to a computer. Trezor Suite will only accept the device if the installed firmware is correctly signed by SatoshiLabs.

This is an absurd security model. Where's the root of trust here? How do I know I am initially talking to an authentic "blank" device, and not a malicious one pretending to be one?

> If unofficial firmware has been installed, your device will flash a warning sign on its screen upon being connected to a computer.

Hopefully, malicious firmware won't meddle with this feature in any way...

The vendor here is either completely clueless, or is trying to paint a better picture for prospective customers despite knowing better.

>Trezor Suite will only accept the device if the installed firmware is correctly signed by SatoshiLabs.

...?

Although I'll concede that I'm now wondering what's preventing compromised hardware from faking this part too. A complex malware could even receive firmware updates, dump them in an unused partition, and report to the connected host that it promises that it's definitely running that firmware, right? Hmmm.

Yes, it could absolutely do that.

The only way around that would be for Trezor to ship their devices with some sort of attestation function (e.g. a private signing key to which they publish the public key, or sign it via a PKI and include a certificate) and validating that, not just the statement "I promise to be running the authentic firmware", a hash over the firmware, a complete firmware dump or anything else not involving a challenge-response or uncloneable function of some sort.

Similar problem to Trusted Platform Module / Secure Boot, right?

In that case the golden keys can leak, but it's better than nothing.

leaked key seems worse in that people will think they have this security measure working for them while they don't. Without this measure there is no illusion at least

Both of these checks seem to rely on the device playing along nicely. During the setup process it can just pretend to be empty, and completely ignore the uploaded firmware. Similarly, the warning sign depends on the device to show it - which the article mentioned was patched out by the attacker.

How does the setup process check for firmware, anyways? If there's a malicious firmware preinstalled I'm guessing it could just lie to the host computer and pretend to be not there until setup is complete. Once an attacker has hardware control, no software can save you.

They replaced the whole microcontroller. Doubt that these checks could resolve this if they were sophisticated enough.

Ah yes, flashing my own firmware. The future of finance.

It's an automatic update. All you have to do is watch the progress bar fill up. Even you could manage it.

I can manage it because I’m a nerd. My technologically inept father on the other hand, could not.

He can't wait a minute or so while the completely automated firmware update completes? Literally all he needs to do is exist. I'm still sure he could manage.

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