The first mention of this is dated 2011... Although bitcointalk hacks were mostly entertainment in nature, there were some when hackers pursued malicious goals
(for example, one of the hacks may have been linked to the Silk Road). Also in those years, a forum for hackers could seem like a tidbit, given that the concentration of tech-savvy people on the forum was much higher than now.
If you want to see the full history of forum hacks read xtraelv's
historical thread.
On September 3, an attacker used a 0-day exploit in SMF to gain administrative access to the forum. This went unnoticed until September 9, when he inserted some annoying JavaScript into all pages. The forum was at this point shut down.
Passwords: It is not known for sure that the attacker copied any password hashes, but it should be assumed that he did.