Ubuntu Forum Security Breach

pinkstuff writes "There has been a major security breach of the Ubuntu Forums database. Every user's email address and salted password has been taken. From the forum home page: Unfortunately the attackers have gotten every user's local username, password, and email address from the Ubuntu Forums database. The passwords are not stored in plain text, they are stored as salted hashes. However, if you were using the same password as your Ubuntu Forums one on another service (such as email), you are strongly encouraged to change the password on the other service ASAP. Ubuntu One, Launchpad and other Ubuntu/Canonical services are NOT affected by the breach."

The hashes are salted

[Dwedit]

The hashes are salted. Who cares about a breach with salted hashes?

Re:The hashes are salted

[TWX]

That's what I'm wondering, given that's the whole point in using that method to store credentials in the first place...

I also have to question the practicality of having different passwords for all one's accounts, especially on things as nonessential as forums. Between work and things that matter I already have to remember too many passwords.

Re:The hashes are salted

[fluffy99]

The hashes are salted. Who cares about a breach with salted hashes?

If they aren't sure of the extent of the compromise, reading salted hashes (assuming they were) might only be part of the problem. Could be they were intercepting passwords on the fly.

Re:The hashes are salted (BUT NOT PROPERLY)

[Rockoon]

How do you reverse an MD5 hash if it is not?

You try all possible inputs at a rate of 180 billion combinations per second. [arstechnica.com]

For an 8 character alphanumeric with a few symbols, thats about 48 bits of entropy, which equates to 1564 seconds (26 minutes) to try every single possible input. Since you used a 128-bit hash on 48 bits of entropy, the odds are very very very good that only one single input will result in the stored MD5 hash.

Thus the attack knows precisely what the original password was in only 26 minutes, which fits the definition of "reversing" the hash in no more than 26 minutes.