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Cracking encrypted LastPass vaults

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Re: Cracking encrypted LastPass vaults

#21

Post by agilob »

poglet wrote: post #18
bedatadriven wrote: post #11

> I downloaded the popular rockyou.txt wordlist and put my actual vault master plaintext password inside Note that is NOT a demonstration of being able to crack an encrypted LastPass vault. The author's exercise wouldn't be feasible without prior knowledge of the master password, or choosing a master password that is present in a list of common passwords. That is consist with what we have heard from LastPass so far.

Agreed, it was a bit disappointing to get to the part where the password was added to the word list. The author does point out that a 2,000,000+ hashes per second could be achieved so it might give insight into how quickly all accounts will be checked against popular word lists. If I was a last pass customer I would be thinking about changing passwords on all accounts.

2,000,000+ H/s on macbook. I heard GPU clusters built purposely for quick hashing got cheaper recently.

Re: Cracking encrypted LastPass vaults

#22

Post by iinnPP »

Does anyone have a good source on brute force and what is and isn't a good idea? I came across the below in a rather important website and am wondering if I should push harder for the to change it.

How secure is a randomized 5 digit pin where you get unlimited guesses but after 10 guesses the pin is reset?

Guessing the pin correctly gets you enough information to open a bank account.

Assuming a system like the above exists, would you consider it a security vulnerability?

Re: Cracking encrypted LastPass vaults

#23

Post by selykg »

CommitSyn wrote: post #15
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…

As a LastPass user (that hasn't logged in since ~2015 :-/ ) can you explain the difference please? > 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.

With 1Password you also have a randomly generated secret key. As I recall it’s a 128-bits, but could be wrong.

To access your vault an attacker will need both your master password and the secret key. These are effectively combined to generate your keys for decryption.

This protects against an attacker gaining access to 1Password servers. They can’t control whether you chose an awful password or not. So to protect them the secret key adds a ton of protection for those with weak, reused, or compromised passwords. Even in those cases an attacker needs to guess the secret key alongside the awful password. Using both the secret key and a strong master password is basically the equivalent of making a vault incredibly secure and, uncrackable using todays technology.

This does not protect against local compromise of a device of yours though, as the Secret Key is stored on device and is accessible. This prevents you from having to type it every time.

Re: Cracking encrypted LastPass vaults

#25

Post by nkrisc »

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.

It’s more secure than passwords the vast majority of people currently use.

Re: Cracking encrypted LastPass vaults

#26

Post by nerdawson »

xvector wrote: post #12
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 English dictionary has about 170k-1M words, and taking the log_2 of that gives us about 16-20 bits of entropy per word. Depending on implementation, we have anywhere from 80 to 100 bits of security. Even on the low end, it should take well over a decade if LastPass chose a good cryptographic hash function with a high iteration count. The problem is that no average person is gonna use a password that long to begin…

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.

Re: Cracking encrypted LastPass vaults

#27

Post by janebrown456 »

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…

[dead]

Re: Cracking encrypted LastPass vaults

#28

Post by hsbauauvhabzb »

iinnPP wrote: post #22

Does anyone have a good source on brute force and what is and isn't a good idea? I came across the below in a rather important website and am wondering if I should push harder for the to change it. How secure is a randomized 5 digit pin where you get unlimited guesses but after 10 guesses the pin is reset? Guessing the pin correctly gets you enough information to open a bank account. Assuming a system like the above…

What does the system hold? Your library loan history or nuclear weapon launch codes?

Assuming it’s reset every 10 attempts, you have lost keyspace and gained random odds. 1:1000000 of getting the password right, 1:500k on average. Assuming I can perform one attempt per second, about 139 hours to successfully brute force a single account. One second is probably pessimistic, most systems are capable of serving much higher rates.

Unless you have fail2ban or MFA, consider the pin a formality.

Re: Cracking encrypted LastPass vaults

#29

Post by resill »

agilob wrote: post #20
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…

> if you tell the cracking tool your password it can indeed crack it... It's called "dictionary attack", but author wasn't bothered doing full brute-force attack or masked attack. It's a demonstration that a laptop can reach `2,000,000+ H/s`.

Actually, he said his laptop maxed out at 1110 H/s. He then said that using multiple GPUs one could likely achieve 2 MH/s and higher.

Re: Cracking encrypted LastPass vaults

#30

Post by sigmoid10 »

agilob wrote: post #20
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…

> if you tell the cracking tool your password it can indeed crack it... It's called "dictionary attack", but author wasn't bothered doing full brute-force attack or masked attack. It's a demonstration that a laptop can reach `2,000,000+ H/s`.

>It's a demonstration that a laptop can reach `2,000,000+ H/s`.

No, the author says their laptop only reaches ~1kH/s. That 2 million number is a pure guess for a multi-gpu setup and that is still pretty weak, unless you have a very good dictionary for a specific target. Brute forcing remotely long alphanumeric passwords is out of the question. So if you have a 8+ character password with upper+lowercase characters and digits that is not close to a real word and was never used anywhere else, you should be perfectly fine after this breach. Only if you have a really shitty password or if you reused it you should probably do something.

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