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Cracking encrypted LastPass vaults

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Re: Cracking encrypted LastPass vaults

#81

Post by yardstick »

t0mas88 wrote: post #61
erros wrote: post #57

Earlier quoted context omitted.

Just out of curiosity I booted up a box with 10x RTX A6000 @ 451.6 TFLOPS Speed.#1.........: 38789 H/s (11.17ms) @ Accel:128 Loops:64 Thr:64 Vec:1 Speed.#2.........: 39017 H/s (11.17ms) @ Accel:128 Loops:64 Thr:64 Vec:1 Speed.#3.........: 38894 H/s (11.16ms) @ Accel:128 Loops:64 Thr:64 Vec:1 Speed.#4.........: 39254 H/s (11.02ms) @ Accel:128 Loops:64 Thr:64 Vec:1 Speed.#5.........: 38626 H/s (11.17ms) @ Accel:128 Loo…

So you're doing 4e10 hashes per second or 390k password guesses per second. At what price per hour?

To be fair I don’t think nation state actors care about the bill. Be it US, China, Russia, Saudi, etc.

Re: Cracking encrypted LastPass vaults

#82

Post by nerdawson »

prmoustache wrote: post #55
Ekaros wrote: post #32

Earlier quoted context omitted.

About 20 000 active words is my understanding. And then the words people pick from is likely from fraction of that.

You don't have to pick all words in the same language. Most people know at least 3 languages well enough. I often make passphrases out of 5 to 6 languages.

No, that’s highly unusual. Maybe people know a handful of greetings / numbers in other languages but I think you’re vastly overestimating the number of people capable of speaking more than one language.

Re: Cracking encrypted LastPass vaults

#83

Post by birdyrooster »

gvb wrote: post #80
lvncelot wrote: post #76

> I downloaded the popular rockyou.txt wordlist and put my actual vault master plaintext password inside (using a quarter of the wordlist), otherwise it would take 6 hours+ to crack. I don't believe the 6 hours+ claim. (Or rather, the "+" is doing some serious lifting in that sentence.) Looking at the password, it's of the correct-horse-battery-staple variety, which could be conservatively estimated at 44 bits of ent…

Your quote includes the most significant part of the article "and put my actual vault master plaintext password inside". He took a word list which did not include his password and put his actual password in the word list. He didn't crack his password, he showed that a brute force password guesser can find passwords that are in its word list. If he wanted to save six hours, he could have put it first in the password l…

Good article is good, it shows brute force works with brute force.

Re: Cracking encrypted LastPass vaults

#84

Post by speedgoose »

xvector wrote: post #65
speedgoose wrote: post #16

Earlier quoted context omitted.

An old Dilbert on this topic: https://dilbert.com/strip/2007-11-16

Except using a secret key doesn't increase the day to day difficulty of using the tool. In fact, it makes it easier.

How do you store the secret key? In your head? In a physical device you must carry around?

Re: Cracking encrypted LastPass vaults

#85

Post by perihelions »

- " Attackers on the other hand can leverage multi-GPU device setups with optimised drivers that could easily reach speeds of 2,000,000+ H/s."

Why wasn't LastPass using memory-hard key derivation functions? I thought that's been best practice for a very long time now: we've known about GPU/ASIC hashing for decades.

Re: Cracking encrypted LastPass vaults

#86

Post by Freaky »

Ekaros wrote: post #32
nerdawson wrote: post #26

Earlier quoted context omitted.

I think the other problem is that when people are thinking up “random” words on their own, they aren’t pulling from the English dictionary. Common vocabulary is a much smaller set.

About 20 000 active words is my understanding. And then the words people pick from is likely from fraction of that.

XKCD estimated 11 bits per "common word", corresponding to a dictionary of ~2000. But that's assuming even distribution across that dictionary, which isn't a reasonable thing to expect a human to do themselves.

Diceware - an actual formalisation of the approach, including recommended means of generating the entropy and specific wordlists - uses 7776 words, for a shade under 13 bits each. EFF have a nice one - https://www.eff.org/dice

The recommended 6 words gives 77.5 bits of entropy per password. At Lastpass's current default iterations of 100k that's about 2^93 SHA256 operations to have better than even odds of breaking it.

To put that into perspective, the Bitcoin mining network is reportedly hashing at 256 quintillion hashes per second right now. At that rate it would take on average 72 weeks to crack.

One extra word bumps that up to 11 millennia, if that's a bit too tractable for comfort.

Re: Cracking encrypted LastPass vaults

#87

Post by malepoon2 »

sinuhe69 wrote: post #42

There is always a potentially critical vulnerability in any centralized password storage. Especially, if it requires a (relatively) simple master password to access. A many factors system like the one of Apple is IMO more secure but also easier to remember because they are all pin/passwords one needs (almost) every day.

1Password is also inherently more secure because of the extra Secret Key. If a breach like this ever happens to them, users with weak master passwords will still be safe.

Also, Lastpass doesn't encrypt URLs. There's really no excuse for that.

Re: Cracking encrypted LastPass vaults

#88

Post by pwg »

alin23 wrote: post #9

Looks like the XKCD way of generating passwords is not as secure. After all, it decreases entropy by a whole lot if 30 characters can be dumbed down to 5 English words with dashes/spaces/periods between. So it’s kind of like using 5 characters from a much larger alphabet (the English dictionary) instead of 30 from a 26 letter alphabet.

The point of the XKCD is not that the method is "secure" in an absolute sense.

It is that it is a method for which the large group of people who would choose "Password0!" as their password [1] can use to create a password they can potentially remember, but such that the chosen password is "relatively" more secure than the basic alternative they would have otherwise chosen.

[1] I.e. the far too common method of "pick a word, make one or two letters capitol, append a numeral, append a !".

Re: Cracking encrypted LastPass vaults

#89

Post by lvncelot »

gvb wrote: post #80
lvncelot wrote: post #76

> I downloaded the popular rockyou.txt wordlist and put my actual vault master plaintext password inside (using a quarter of the wordlist), otherwise it would take 6 hours+ to crack. I don't believe the 6 hours+ claim. (Or rather, the "+" is doing some serious lifting in that sentence.) Looking at the password, it's of the correct-horse-battery-staple variety, which could be conservatively estimated at 44 bits of ent…

Your quote includes the most significant part of the article "and put my actual vault master plaintext password inside". He took a word list which did not include his password and put his actual password in the word list. He didn't crack his password, he showed that a brute force password guesser can find passwords that are in its word list. If he wanted to save six hours, he could have put it first in the password l…

Yes, which is why I'm so skeptical of that claim. "I've put the password in because otherwise it would've taken 6 hours" makes no sense at all - even putting aside my napkin calculation; if it would've taken an afternoon of crunching, why wouldn't you just have done that?

Re: Cracking encrypted LastPass vaults

#90

Post by oefrha »

perihelions wrote: post #85

- " Attackers on the other hand can leverage multi-GPU device setups with optimised drivers that could easily reach speeds of 2,000,000+ H/s." Why wasn't LastPass using memory-hard key derivation functions? I thought that's been best practice for a very long time now: we've known about GPU/ASIC hashing for decades.

Where’s the ASIC cracking 100,100-iteration PBKDF2-HMAC-SHA256 at 2M H/s? Let alone GPUs. TFA pulled that number out of nowhere.
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