You can of course ban them from your server but, it will not go onto the pbbans.com MBI. You can however report the user to their ISP and you can even take legal action against them. You need to make sure that they weren't using a proxy so that you can verify if it's really a known person but, the next question is how do you know that they hacked your server? Guessing the rcon? That's one of the major reasons that people upgraded to the latest version of your game to avoid a player from getting your rcon since previous versions of the game were vulnerable to getting that information if you didn't know how to hide it. There are other programs which are supposed to safeguard your server against someone being able to crash it. So you might want to look into one of those programs that would stop the Q3info boom attack. http://qmm.planetquake.gamespy.com/ is a program that is used to help stop such crashes.