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Critical flaw in Trezor hardware wallets

121 points| menduz | 6 years ago |blog.kraken.com

49 comments

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Ardren|6 years ago

The original response about these type of issues [1] rubs me the wrong way

In particular this statement:

> That being said, we were surprised by Ledger’s announcement of this issue, especially after being explicitly asked by Ledger not to publicize the issue, due to possible implications for the whole microchip industry, beyond hardware wallets, such as the medical and automotive industries.

As I understand they are using a standard STM32 chip for these wallets, and relying on it's basic protection. Companies make real processes designed for securely storing data, why aren't they using them? Instead they are suggesting that there is no alternative and everyone is vulnerable to this style of attack.

Edit: I missed some of the backstory. They don't mention that option as their competitor (who found the security issues) already uses a secure element, like a sane person.

[1] - https://blog.trezor.io/our-response-to-ledgers-mitbitcoinexp...

mistahenry|6 years ago

To me, this is full admission of a complete lack of security competency. Building a hardware wallet without using a smart card or some other secure element that at least has mitigation’s against voltage/clock glitching, detects light, reduces the ability to measure power consumption, etc is negligent.

Either they don’t know how to design secure solutions or they wanted to use cheaper chips since tamper resistant chips cost more. Neither is a good look

rdl|6 years ago

Trezor is designed to protect against remote/logical attacks (including a compromised host). It isn't really hardware protected in any meaningful way against local access. This lets users inspect/validate their own hardware better, though.

The issue is most users (reasonably, IMO) assume physical protection for their hardware wallets, at least against someone getting temporary access and without insane levels of resources. That is fairly safe using a Ledger today (barring an undisclosed vuln); that's why I think the Ledgers are somewhat better.

qertoip|6 years ago

Exactly.

I would definitely pick Coldcard over Ledger though.

Coldcard is open source and open hardware to a much greater extent, while still using secure element for secret storage and PIN counter. It also offers advanced security features like proper multisig support, airgaped operation, roll-your-dice entropy input, etc.

sneak|6 years ago

I think people in practice buy these and use them thinking that they are secure against physical theft because of “encryption” and requiring a pin.

This shows that assumption to be totally false.

londons_explore|6 years ago

Why don't all silicon chips have glitch and overvoltage detection?

It would seem very easy to put a pair of fets in such a way they detected sudden voltage changes (via their gate capacitance). That could then be used as an input to a circuit which ensured the chip is properly reset by asserting the reset line for at least 1 clock cycle.

This should probably be paired with brown-out detection, although that's power hungry, so I can see why people might not want it.

This wouldn't only have security benefits - lots of electronic designs might be accidentally glitching their microcontrollers due to poor design of other circuits, and having the chip reset in a predictable way is much better than undefined behaviour.

pjc50|6 years ago

Brownout detection is definitely one of those things to turn off for low-power operation. I suspect glitch detection is harder than it sounds, too.

sschueller|6 years ago

Probably due to price. Some applications it doesnt matter if the chip can be glitched but getting them at a lower cost does matter.

skunkpocalypse|6 years ago

> Why don't all silicon chips have glitch and overvoltage detection?

Reliability. This is basically the microchip version of Boeing's MCAS.

The circuit you describe is not only an analog circuit, but is in fact a noise amplifier. You're now shipping a chip containing a noise amplifier that drives the device-wide reset line.

What could go wrong?

The stuff you describe is very, very difficult to get right, and beast-mode insanely difficult to troubleshoot or even diagnose when it goes wrong.

It's also very sensitive to manufacturing variations. So if there is a problem with the circuit, it'll probably only affect a few batches. Which, Murphy's Law and all, will be the batches that wind up in the hands of your most important customers.

Stuff like this can bankrupt a chip company if you get it wrong, and there's no way to be sure you got it right. At most you put it in your super-high-end ultra-secure product line, so long as that line's sales are small enough that you can afford a recall.

nnx|6 years ago

Nothing in this flaw is a surprise considering Trezor does not even use a secure element (unlike Ledger).

pat2man|6 years ago

It’s surprising considering how cheap SIM card chips are. It’s not hard to do secure elements these days, at least at scale.

literallycancer|6 years ago

What makes you think the Ledger secure element provides any meaningful security?

thinkloop|6 years ago

Some lucky people will be able to restore lost crypto.

FatalLogic|6 years ago

That really has happened. A legit owner used an old vulnerability to rescue $30,000 from a Trezor wallet when he forgot the pin.

https://www.wired.com/story/i-forgot-my-pin-an-epic-tale-of-...

Luckily he hadn't updated the firmware so the vulnerability wasn't patched on his device, but despite that, it took a long time and was not easy. But like this newer vulnerability, it would almost be impossible if he had also used a strong passphrase, as Trezor recommends.

rohanagarwal94|6 years ago

Every wallet is physically hackable, that is why we are building Cypherock where we introduce a second variable that is locations using Shamir Secret Sharing on the private keys. I would love to have the opinion from the community on it - https://cypherock.com.

paulpauper|6 years ago

This may seem bad but how many people have lost crypto because of this? You are more likely to have your crpto stolen when transferring crypto to your trezor when setting it up.

tmlee|6 years ago

No hardware can protect itself from absolute physical compromise; perhaps a self-fuse burner when somebody tries to open it

tzumby|6 years ago

Banks store private keys for their ATMs in hardware security modules (HSM) and there are lots of crypto exchanges that started doing that. One of the features is private keys self destruct when tampering is detected. If you have a backup you’ll be able to recover the private key. While I agree that Trezor wasn’t designed with this in mind, I think it’s a good idea to include this feature. Not sure about the size requirements for that though, it might make the device significantly bigger.

quelltext|6 years ago

Doesn't the iPhone claim to be able to protect from physical access?

6gvONxR4sf7o|6 years ago

With the right systems in place, you can be protected from physical compromise. For example, if my credit card is stolen, I call visa and I'm fine.