They stole details of Brink users, and details of Bethesda Forum users.
Yesterday, the hacker group posted additional information about the hack.
“Bethesda, we broke into your site over two months ago. We’ve had all of your Brink users for weeks. Please fix your junk, thanks!”
“Please find enclosed everything we took, excluding one thing — 200,000+ Brink users. We actually like this company and would like for them to speed up the production of Skyrim, so we’ll give them one less thing to worry about. You’re welcome!”
They later asked Bethesda to give out information of The Elder Scrolls V: Skyrim, and feature a LulzSec top hat in the game, or they would give out the details of the users.