3 ms·

(26+10)**12 is 4738381338321616896 combinations. 300,000 attempts per second isn't going to have an easy time cracking that, so I don't see what the problem is

by jart 4y ago

(26+10)**12 is 4738381338321616896 combinations. 300,000 attempts per second isn't going to have an easy time cracking that, so I don't see what the problem is with LastPass' requirements.

mint2 4y ago
“(26+10)*12” is irrelevant Please Refer back to “If you take the most popular 1M passwords and attack the master password…”
- jart 4y ago
  It is relevant, because it's where LastPass' responsibility ends. It's not their job to prevent people from being stupid and choosing a password like `lovelovel0ve` but rather to define a requirement that allows for sufficient complexity.
  - rsj_hn 4y ago
    I think a reasonable feature for a password manager would be to do NIST recommended checks, such as comparing passwords to databases of known compromised passwords and alerting/recommending rotation or rejection of the password if a match is found (depending on password entry UI). Obviously you're not going to get a complete db of known hacks, but a db of most common X million passwords, updated every 6 months or so, is pretty good, and is what I would expect a good password manager to do. LastPass is in the bad situation of needing to provide excellent security in a product that people really aren't willing to pay a lot of money for. Some of the websites that ask for passwords are in a better position to do this, but then you don't get the benefits of a password manager. Same issue for the the other password managers out there.
sliken 4y ago
Yes, those with pure random passwords are safe. What percent of LastPass users do you think use a very hard to remember completely random 12+ character password? Personally I use either VaultWardens random password generator, or some variation of the XKCD like 4-6 words out of 100,000 which give me somewhere north of 64-96 bits of entropy. Cracking that @ 300k/sec takes a quite long time. I like the XKCD approach, because it's particularly voice/phone friendly. However much more common in the real world is to pick an easy to remember password with low entropy, something like PinkFloydRocks, which fail because of lack of a number and change it to P1nkFloydRocks. Or maybe PinkFloydRocks<2 digit birth year>. Quite a few plaintext passwords have been leaked, some even with helpful popularity tables. I'd place bets that a decent percent of LastPass's vaults would fall to a top 10,000 12 character or longer popular passwords. I suspect someone is testing this right now.
- jart 4y ago
  I had a feeling you were speaking from experience with that 300k number. Does that include the cost of password stretching? As others have pointed out in this thread LastPass uses PBKDF2 with 100,000 rounds. Even if you have a supercharged PC with 6x ATI Radeon HD 5870 you're only going to be able to derive 25k AES keys per second tops to even try, since that doesn't include the cost of deciphering. So how do you do it?
  - sliken 4y ago
    No experience, just saw a post on someone attacking LastPass Vaults. It looked to include everything. Apparently they wrote a tool specifically attempting password recovery on LastPass vaults and with a RTX 2070 (2 generation old) managed 309,000 against the 5000 iteration flavor and 15,500 against the 100,100 flavor. More info at: https://blog.elcomsoft.com/2020/04/breaking-lastpass-instant-unlock-of-the-password-vault/ https://blog.elcomsoft.com/2020/04/breaking-lastpass-instant...

by jart 4y ago

(26+10)**12 is 4738381338321616896 combinations. 300,000 attempts per second isn't going to have an easy time cracking that, so I don't see what the problem is with LastPass' requirements.

mint2 4y ago

“(26+10)*12” is irrelevant Please Refer back to “If you take the most popular 1M passwords and attack the master password…”

jart 4y ago
It is relevant, because it's where LastPass' responsibility ends. It's not their job to prevent people from being stupid and choosing a password like `lovelovel0ve` but rather to define a requirement that allows for sufficient complexity.
- rsj_hn 4y ago
  I think a reasonable feature for a password manager would be to do NIST recommended checks, such as comparing passwords to databases of known compromised passwords and alerting/recommending rotation or rejection of the password if a match is found (depending on password entry UI). Obviously you're not going to get a complete db of known hacks, but a db of most common X million passwords, updated every 6 months or so, is pretty good, and is what I would expect a good password manager to do. LastPass is in the bad situation of needing to provide excellent security in a product that people really aren't willing to pay a lot of money for. Some of the websites that ask for passwords are in a better position to do this, but then you don't get the benefits of a password manager. Same issue for the the other password managers out there.

sliken 4y ago

Yes, those with pure random passwords are safe. What percent of LastPass users do you think use a very hard to remember completely random 12+ character password? Personally I use either VaultWardens random password generator, or some variation of the XKCD like 4-6 words out of 100,000 which give me somewhere north of 64-96 bits of entropy. Cracking that @ 300k/sec takes a quite long time. I like the XKCD approach, because it's particularly voice/phone friendly. However much more common in the real world is to pick an easy to remember password with low entropy, something like PinkFloydRocks, which fail because of lack of a number and change it to P1nkFloydRocks. Or maybe PinkFloydRocks<2 digit birth year>. Quite a few plaintext passwords have been leaked, some even with helpful popularity tables. I'd place bets that a decent percent of LastPass's vaults would fall to a top 10,000 12 character or longer popular passwords. I suspect someone is testing this right now.

jart 4y ago
I had a feeling you were speaking from experience with that 300k number. Does that include the cost of password stretching? As others have pointed out in this thread LastPass uses PBKDF2 with 100,000 rounds. Even if you have a supercharged PC with 6x ATI Radeon HD 5870 you're only going to be able to derive 25k AES keys per second tops to even try, since that doesn't include the cost of deciphering. So how do you do it?
- sliken 4y ago
  No experience, just saw a post on someone attacking LastPass Vaults. It looked to include everything. Apparently they wrote a tool specifically attempting password recovery on LastPass vaults and with a RTX 2070 (2 generation old) managed 309,000 against the 5000 iteration flavor and 15,500 against the 100,100 flavor. More info at: https://blog.elcomsoft.com/2020/04/breaking-lastpass-instant-unlock-of-the-password-vault/ https://blog.elcomsoft.com/2020/04/breaking-lastpass-instant...