I searched the hack. It was an admin hack then re-directed the site. While in the admin control panel, the hack finds e-mail addresses of users and sent out the e-mail message to users. It's a very complicated hack to get in. Once in, they apply a re-direct to the site. Actually, they did no harm and it's easily repaired. However, once in the admin they could wipe out the site. They could also attach a virus to an e-mail. The whole thing sucks.
BTW - we use the same software for our forum.
It's the Anonymous group that you may have heard about in the news.