Two Bitcoin related websites were hacked, namely Btc-E.com (a Bitcoin exchange acting similar to a foreign currency exchange) and Bitcointalk.org (the largest Bitcoin discussion forum in the world).
Btc-E.com had 568,355 users hacked in October of 2014. Btc-E.com data contains usernames, emails, passwords, ip addresses, register dates, languages and some internal data such as how many coins the user had.
They used some unknown password hashing method which currently makes their passwords completely uncrackable although that may change. This is good because if the passwords were easy to crack, hackers could log into the exchange and start stealing members Bitcoins.
Bitcointalk.org had 499,593 users hacked in May of 2015, and they do know about the breach. Bitcointalk.org data contains usernames, emails, passwords, birthdays, secret questions, hashed secret answers and some other internal data.
Only 44,869 (9%) of users on Bitcointalk.org used MD5 hashing with a unique salt for passwords. Of those, LeakedSource.com was able to crack 30,389 or 68%. The remaining 91% of user passwords were hashed with “sha256crypt” and LeakedSource estimates it would take them about a year to crack an estimated 60-70% of them. This method of password storage is far superior to nearly every website they say they’ve seen thus far.
Information Provided By: LeakedSource.com.