[amjo324]

"The passwords are stored as SHA1 hashes of the first 10 characters of the password converted to lowercase. That's right, truncated and case insensitive passwords stored without a salt"

I'm surprised this fact is not getting more attention. In theory, this means that a MySpace account with a password of Welcome1234567 could be logged into with a password attempt using any of the following examples:

* Welcome123

* welcome123

* WeLcOMe123456789

* welcome123anythingafterthe10thcharacterdoesntmatter

In essence, case sensitivity and the 11th character onward are completely ignored. This vastly reduces the total key space. To compound the problem, SHA-1 has been used which is not suitable for password storage (salted or otherwise) because it's an intentionally fast algorithm. This means an attacker can more efficiently run all permutations through the hash function to find a hash match and hence the password. In fact, as I've described above, the attacker doesn't even need to retrieve the exact password to gain access to the account. They just need an input that will produce an identical SHA-1 hash (i.e. an input containing the same first 10 (case insensitive) characters as the original password).

Based on the work I've done reversing password hashes in bulk (legitimately for clients in penetration testing engagements), I'd suggest that at least 80% of the reported ~360 million hashes could be reversed within a few days with access to the full data set and $5k worth of commodity GPU hardware. And you can guarantee that these passwords will be used in future attacks against other web sites because of how common password reuse is. Frightening.

[leohutson]

My previous bank ( ASB ) used to truncate passwords. I found out because one day I was trying to enter my password and it kept refusing it until I left off the last two characters. It turns out that they had stopped truncating or perhaps just increased the length, and so my 10 character password was just an 8 character one all along. It kind of boggles my mind that a bank would do that.

[userbinator]

Not quite as frightening as the schemes some financial institutions use... one that immediately comes to mind is 6 digits, no more or less, and probably stored in plaintext. Then again, bruteforcing attempts are usually very easily noticed and kept from succeeding on such systems.

[amjo324]

Sure. But it would be a stretch to find any financial institution with as many as 360 million customer records. Maybe one of the state-owned commercial banks in China being the exception.

And more to the point, the corresponding email addresses and/or usernames in the MySpace breach are leaked along with the password hashes. The same email address and password combinations will be tried on other web sites (e.g. Amazon, Facebook) with a reasonable chance of success. No brute force necessary.