Arucardo

If you can be absolutely certain about who's doing it there's definitely one thing you can do, get in touch with Steam Support. For example the guy mentioned in the first post of this thread wasn't exactly hard to track down (steam account and all) BUT I have to stress this, don't start reporting anything just yet because he could've been spreading it unknowingly after getting infected on a previous server. If multiple server admins start seeing this guy appearing and the server getting hacked shortly after then it might be worth looking in to. I highly doubt Valve is just going to turn a blind eye to a steamworks supported game getting griefed/hacked in such a way. If nothing else the person responsible has a good chance of losing his entire Steam account. Again, please don't start a witch hunt if you're not absolutely certain about the person responsible.