Cracking encrypted LastPass vaults • Hacker News Board

Re: Cracking encrypted LastPass vaults

#101

Post by zamalek » Sun, Dec 25, 2022, 5:39 PM UTC

gchadwick wrote: post #13

>I downloaded the popular rockyou.txt wordlist and put my actual vault master plaintext password inside I was hoping for an exploration of how quickly one might crack a lastpass vault looking at different strength passwords and different iteration counts. Instead the author has simply demonstrated that if you tell the cracking tool your password it can indeed crack it... I guess you can at least follow what they did…

> how quickly one might crack a lastpass vault looking at different strength passwords

The iteration count is 100100. So at 2000000 H/s, that's 19 passwords/s. A 6 alphanum password has 36^6 combinations. 36^6 passwords / 19 passwords/s = 114567491s =

3.6 years

With 65 (base64 + space) characters:

125.9 years

Divide those by 20 (100100/5000) for the lower iteration count. Multiply them by 6 if the password has up to 6 characters.

Re: Cracking encrypted LastPass vaults

#102

Post by speedgoose » Sun, Dec 25, 2022, 5:40 PM UTC

ziml77 wrote: post #97

speedgoose wrote: post #84

Earlier quoted context omitted.

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

On a printout and even inside the vault itself. You only need the key the first time you unlock the vault on a device. After that the key can be encrypted locally with just the master password or kept in the TPM (or the platform's equivalent).

But if you don’t have the printout and a device with the encrypted key, you cannot access anything. I’m not sure users are going to be happy.

Re: Cracking encrypted LastPass vaults

#103

Post by upofadown » Sun, Dec 25, 2022, 5:52 PM UTC

This is an obvious demonstration, but I think still an important one. Lastpass has said this about the breach:

> These encrypted fields remain secured with 256-bit AES encryption and can only be decrypted with a unique encryption key derived from each user’s master password using our Zero Knowledge architecture.

That all sounds great but the number of bits of AES and the cool "Zero Knowledge" designation is completely irrelevant here. It entirely depends on the strength of the user supplied password. So if your password is weak you are in trouble. The other message here is that if your password was installed before 2019 it is probably going to be a lot easier for an attacker to guess.

That's it, that's the whole thing, but it still needs to be shown...

Re: Cracking encrypted LastPass vaults

#104

Post by 404mm » Sun, Dec 25, 2022, 6:03 PM UTC

xvector wrote: post #2

Good tutorial. This is why I prefer 1Password, as it requires the secret key to be compromised in addition to the Master Password, thus providing protection against a weak master password. I've always thought it foolish to recommend solutions like LastPass and BitWarden, which don't require a secret key. It is dangerous design, prioritizing ease of onboarding over actual security. The average consumer needs an autoge…

Nice break down and explanation!

How does 1P compare to built in keychain (Apple devices) when it comes to security? My guess is that there’s encryption key for the vault and private key for access? I’ve been using 1P for family secrets for a while but I’m grieving more and more frustrated with frequent technical issues (unreliable sync, browser extension loses connection to 1P and has to be restarted). And I’m considering switching to OS built in keychain and maybe 1P personal for family shared secrets?

Re: Cracking encrypted LastPass vaults

#105

Post by paulpauper » Sun, Dec 25, 2022, 6:08 PM UTC

So how was the other guy's account cracked? https://twitter.com/cryptopathic/status/1606416137771782151

this should not be possible to bruteforce

Re: Cracking encrypted LastPass vaults

#106

Post by lynndotpy » Sun, Dec 25, 2022, 6:12 PM UTC

EMM_386 wrote: post #95

Yes, I too cracked most of my university's passwords on a UNIX system using a dictionary and a tool in 1995. There really isn't anything new here.

This article is valuable because it demonstrates how to get the password out of Lastpass. Figuring that out is the majority of the human effort.

Re: Cracking encrypted LastPass vaults

#107

Post by paulpauper » Sun, Dec 25, 2022, 6:24 PM UTC

shrx wrote: post #17

Reminder to never use pixellation to obfuscate sensitive data: https://github.com/bishopfox/unredacter

funny when people use burring to hide twitter usernames. its like you know you can just search twitter for the tweet verbatim and it will show the user, right?

Re: Cracking encrypted LastPass vaults

#108

Post by eli » Sun, Dec 25, 2022, 7:23 PM UTC

latchkey wrote: post #99

t0mas88 wrote: post #48

Earlier quoted context omitted.

With 8 characters, which is way below all recommendations and using only alphanumeric + the simple special chars on the keyboard you're looking at over 7 * 10^14 possibilities. If you could do 100 million hashes per second (that seems to be possible with hardware looking at crypto stuff), the way I understand the setup you're still up against the 100100 iterations in the key derivation algorithm. So that's 7 * 10^19…

I have access to 34,000+ GPUs, right now. All that I need to do is pay for power, which is at lowest rates. Who wants to crack some hashes?

Where are you where power is at its lowest rates?

Re: Cracking encrypted LastPass vaults

#109

Post by xvector » Sun, Dec 25, 2022, 8:25 PM UTC

speedgoose wrote: post #102

ziml77 wrote: post #97

Earlier quoted context omitted.

On a printout and even inside the vault itself. You only need the key the first time you unlock the vault on a device. After that the key can be encrypted locally with just the master password or kept in the TPM (or the platform's equivalent).

But if you don’t have the printout and a device with the encrypted key, you cannot access anything. I’m not sure users are going to be happy.

To lose your passwords, you have to lose literally every device you have LastPass on and your printout and any E2EE backups of the key (e.g. to iCloud.)

Re: Cracking encrypted LastPass vaults

#110

Post by IshKebab » Sun, Dec 25, 2022, 9:02 PM UTC

crazygringo wrote: post #67

IshKebab wrote: post #63

Earlier quoted context omitted.

That would be a lot more convincing if they had a blind demonstration. As noted in the readme, getting the CSS exactly right is both critical to making it work and extremely difficult. I'd wait until someone actually uses that software successfully in anger before we declare that you should never use pixelation. Obviously black bars are better but sometimes you don't care that much about keeping the data secret.

If it's a pixel-perfect screenshot, getting the CSS right is actually extremely easy as long as there's surrounding text. It's easy to recognize a font, easy to figure out its size, and easy to figure out the coordinates. No more than a couple minutes of trial and error. It's only difficult if it's been resized+compressed lossily, if it's a photograph of a screen, etc. And since font rendering can be different betwee…

This screenshot looks pretty pixel perfect. Maybe have a go if it's so easy!