How did LastPass master passwords get compromised?

Re:How did LastPass master passwords get compromised? by md_ on Thursday December 30, 2021 @11:38AM (#29738168)

> There exists no computer system than can crack an AES256 encrypted document. The weaknesses are in the protocol.

Well, or in the human-chosen passphrase. There are plenty of systems that can brute force an 8-character alphanumeric password run through PBKDF2 for 100,000 rounds.

Per https://support.1password.com/pbkdf2/, that costs...about $60k.

So keeping the ciphertext safe is in fact a very reasonable precaution, especially if you have a fairly short input passphrase or are not using a ton of rounds of key stretching.

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Re:How did LastPass master passwords get compromised? by twicetwice on Thursday December 30, 2021 @11:51AM (#29738318)

I simply use a 40ish character passphrase. My primary attack vectors are keyloggers/local malware and browser/extension vulnerabilities, which also apply to a local ciphertext.

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Re:How did LastPass master passwords get compromised? by SavantIdiot on Thursday December 30, 2021 @11:56AM (#29738359)

You are correct: if the password used to create the key is trivial, then there definitely exists hardware that can guess AES256 passwords even if a KDF is used weakly.

I'm not sure how to read that table. Is that really the cost for a 100,000 iteration PBKDF2?!?

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Re:How did LastPass master passwords get compromised? by md_ on Thursday December 30, 2021 @12:24PM (#29738705)

I have not checked 1Password's math--they just come up in the results for "PBKDF2 cost of brute forcing". ;)

But yes, it matches my intuition--brute forcing human-strength keys is surprisingly cheap. (And I don't know if they're taking into account the discount if you have custom ASICs for this, defend against which is the argument made for scrypt instead.)

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