Forum hacked using 3.8.2
 

I would like to note that today our community was hacked somehow. They were able to get into the Mysql through the .css. I found a log file in my ftp that showed once a user logged in there username and password were added to that log file which they could pull from our domain. What could have been the security breach if you or anyone knows. I am now going to install the newest updates which the guys says he can still get into the newest version. Also I am going to implement 2 seperate firewalls. Is there anyother things I need to worry about or need to implement.

Any and all advice will be helpfull. Just so everyone knows whats going on.