Topic: PIN codes and Hardware Wallets - page 2. (Read 496 times)

I'm not sure that they added such delay deliberately, but as soon as you attack an embedded device (from a separate PC), you either have inherent delays in the communication or need to add some yourself since the device may not be ready to respond fast enough or the data isn't yet available. It's not like bruteforcing a software target on the same machine which could process PIN attempts at incredible speeds.

If there is a secure / non-bypassable PIN counter implementation that doesn't rely on the secure element, I currently see no technical reason holding hardware wallet developers back from using that instead of the more destructive method. I doubt that any 'non-destructive' implementation is as secure as one that leverages secure chip counters, though.

But surely it you can bypass the PIN counter altogether to earn yourself unlimited attempts, then you would also bypass any delay imposed on repeated attempts. In such a case it then becomes fairly easy to set up a program to just brute force every combination from 00000000 to 99999999. And with the seed dumping vulnerability you mention now patched, then if such an attack were possible then I suspect we would have seen it by now.

So if it seems not possible to bypass the PIN counter, then that comes back to the original question of what does bricking after x attempts rather than resetting after x attempts achieve, other than forcing you to buy a new device?

I'm sure that on a hardware wallet like Trezor without secure element, this is a pretty viable attack vector. My guess is that if you already go through the trouble of doing hardware attacks, you may as well skip all the boring bruteforcing that is still required in this example and 'go for gold', directly dumping the seed during the boot process, like Joe Grand did it. Or use any other attack type that doesn't require waiting for potentially days or weeks.
This actually makes this list even more interesting, because we can now easily point out which hardware wallets have a non-destructive 'attempt counter', while also having a secure chip. These are exactly the devices where it may make sense to attempt finding the storage location of the counter (obviously outside the secure element) and attacking that to get unlimited PIN entry attempts.

That's an interesting angle which I had not considered. It does however raise the question that if this were the case, why have we not seen the PIN counter being reset on other devices which do not use this hardware counter? Given how eager hardware wallet manufacturers are to disparage the competition, if this were possible would we not have seen a disclosure that "X wallet's PIN counter can be bypassed"?

What I can extract from available information by Foundation (since I've looked up more information about this wallet than any other) is this.

I guess they chose to use the built-in counter mechanism of the secure element, to make sure that nobody is able to bypass the counter. If they stored the number in flash for instance, a skilled attacker could reset the number to 0 before hitting the n-th attempt at which it would factory reset (or brick itself). This could even be automated with relatively limited required hardware and combined with a brute-force PIN guessing script.
The downside is that the secure chip with this secure built-in counter probably doesn't have the ability to factory reset the device when the counter is reached, since it doesn't have as 'direct' and immediate, full control over the main processor, the type of acces it does have to its own internal secure storage 'slots'.

Therefore it leaves you with 2 options:
(1) Use the secure counter of the secure element, but when it reaches its maximum value, it can only trigger a 'permanent brick' as it's not capable to factory reset the device.
(2) Use an insecure counter stored in flash, and have the freedom to do with your MCU what you want. Erase the flash, restore to factory settings, brick it, you name it.

I'm not sure that this is 100% accurate, but it may be a technical limitation actually.

My point exactly. If the argument is that bricking a device is safer than simply factory resetting because you cannot guarantee that all the data is destroyed with a factory reset, then they are pretty much admitting that they think data can be extracted from their device via some method. In which case, whether the device resets or bricks itself is irrelevant, since no attacker would attempt to brute force an unknown PIN with 3/10/20 whatever attempts, and instead proceed to extract the data through whatever these methods may be.

Also, if the argument is that bricking is more secure than a factory reset, then the devices should come with a huge warning to never sell your device, give it to a friend, etc., since even if you factory reset it your wallets would be at risk. As far as I am aware, no device comes with such a warning.

Good point and good question! I will ask @zherbert, since I'll also start working on my Passport v2 review soon^TM. So I can get their answer to this bug / feature question in there, as well.

That makes no sense though; in case the thief / attacker finds a wallet that just erases itself to factory settings after 3 attempts, they can't recover it any more or less easily than if it destroys itself after the same amount of attempts, right?

I think from a business perspective this is the goal, so they buy again if they forget it. But they can also say something along the lines that it protects your assets if somebody stole them. In case you lost your wallet, the hacker has no chance to recover it while you can with another device/wallet as long as you have a backup.

What is the benefit of a device bricking itself after x number of attempts, rather than just factory resetting itself? Assuming in both cases there is no chance to recover access to the original wallet without knowledge of the seed phrase, then bricking instead of simply securely wiping/shredding the data seems like a bug, not a feature, and simply forces the user to purchase another hardware wallet rather than just using their newly reset one to recovery from a back up.

Given that we know plenty of people leave hardware wallets lying around where they shouldn't, on desks, in drawers, etc., I'd be pretty pissed if a kid (for example) picked it up thinking it was some kind of phone and inadvertently permanently bricked my $200+ device.

I wanted to say how American of them, but they are assembled in Canada. Still, close enough.

I remember reading that ColdCard has a unique PIN that you can set up that bricks your device just by entering it once. I forgot what it was called, so I had to look it up. BrickMe PIN
Enter it once, and it achieves the same result as a wrongly entered main PIN 13 times.

There is a difference between these two. If you wrongly enter your PIN 3 times on a Ledger, the device will reset itself to factory settings. It can still be used but you need to recover it from seed. If you enter the PIN wrongly 13 times on a ColdCard, the HW gets permanently bricked. It's destroyed and you can't use it any longer. Ever.

It doesn't have to be connected and accessible with the PIN. You can set a temporary passphrase valid only for that session and until you turn the device off. In that case, you don't need to attack a new PIN to your passphrase account.

Unless a user is a complete newbie this would never be an issue.  Let me explain:  The very FIRST step a user should complete on ANY hardware wallet is a complete multiple backup of the SEED used  -------- period!!  If I forget my PIN or misplace my encryption SD card I would simply blow away the Trezor and recreate my wallets from scratch.  Very easy to do!!

My comments did assume you were using PIN=password in your post above.  If you actually meant passwords and not a PIN then you are correct.  Just wanted to make sure some of our readers are clear that PINs don't present a big problem with proper SEED backups.  .02

PIN attempts:
Regarding PIN attempts on hardware wallets.  Trezor T allows for 16 attempts.  What do you think the odds are of someone guessing my unique (used nowhere else ever) 9 digit PIN in only 16 attempts.  Basically zero!!  With advanced encrypted PIN on SD you can't even enter a PIN without the file.  The exception is for my Wipe PIN where the wallet wipes!

I agree with m2017 here.
Ledger device will not break after 3 attempts, it will just reset. And the owner has the private key.

If an attacker just enter into my house and find the device he may discover the secret code in 17 attempts that some those device allow. This is not a brute force, he is trying easy pins.

Although people should not use birthdays, year of birth,etc as pin code, those are VERY common. Someone may just try a few dates or other easy to remember combinations and discover the pin.

I feel safer with 3 attempts and device is reseted.

Just to illustrate... When I am traveling and I need wifi passwords, I just try "nameofstore2022" or 2021, 2020 etc and it works like 10-20% of the times.

There is no 'perfect number', but if your device bricks after 3 wrong entries, a false-positive is quite likely.
A good password / PIN is not significantly more likely to be brute-forced if you give an attacker 3 or 20 tries. If it's 3 or 3000, it could be a different story.

Basically, brute-forcing 20 attempts in the real world is just as unlikely to unlock the device as if you only had 3.

• SecuX - If you enter the PIN incorrectly five times, it'll reset the device ^{[refer to #8 and #10]}.
• Ngrave - Ten wrong PIN codes results in the device wiping itself ^[source].

While I was reading the "Wallet and Device Issues ^{[refer to #5]}" section on SecuX, I discovered they also have such a thing in place.

Can you explain in more detail what is the advantage of more attempts to enter a PIN code than 3 for Ledger? I may be wrong, but it seemed to me that the more attempts there are, the more chances there are to pick up a PIN code for a non-owner of the hardware wallet. At the same time, the more times, the more chances the owner will have to remember his PIN code. It's like you need some average value, which (in my opinion) will be optimal - 5-7 times or a little more (may be ~10 times).

I never said I am against passphrases at all, I just don't like how ledger is connecting them with PIN codes.
There is a big difference between this two (PIN vs Passphrase) so I don't want to mix them together, and yes I know Trezor have passphrase option like most other hardware wallets.
People often think that Password is the same as Pin or as Passphrase, but that can only create confusion.

Why not? Passphrase just add an extra security. I don't see downsides. It is designed specifically for physical attacks.

The trezor device does exactly the same, but you don't have the extra pin to access it easily.
https://wiki.trezor.io/Passphrase

I think that ledger devices are also encrypting PIN's, but I am not sure about all other hardware wallets.
There could be a problem with losing access to your funds if you forget encryption password so I would be very careful with this.

I would disagree.
Less is not better, especially compared to all other hardware wallets.
There is a good reason why everyone else (except ledger crap) made much more wrong attempts for PIN, some can even brick a device.

As far as I know only ledger is using multiple PIN's, but I think they are mixing and connecting this with wallet passphrase, and I don't like this very much.

Nice idea for a topic, I didn't know about all those variations since our last chat in another topic.

Since your topic is about PIN codes in general, I will suggest that you add a session about "multiple PIN codes". Some hardware wallets allow you to use multiple PIN codes when you add a passphrase. This is interesting because you can have 2 wallets in the same device, and even a "hidden" one in case of a physical attack.

Ledger nano allows 2 PIN codes:
https://www.ledger.com/academy/passphrase-an-advanced-security-feature

In ledger nano case, both wallets (one for each PIN) will have the same seed, but one of them will have a passphrase. So, they are different wallets.

Looking through the list above, I have an idea that only Ledger has the most adequate number of attempts to enter a PIN (although it's not ideal).

Ledger wallet -3 times
Trezor wallet - 16 times
Coldcard wallet - 13 times
Passport wallet - 21 times
Keystone wallet - 12+5 times

Although in my opinion, the optimal amount could be about 5-7 times. More than 10, as for the proposed devices, I think it’s too much and the owner of the hardware wallet doesn’t need so much (he will dial the correct PIN with fewer attempts), while the attacker gets more chances to pick up a PIN with a large number of attempts.

Of course, this is not the whole list of existing devices, and most likely OP will add information about others later too.