Serv-u has quite a few exploits, I've heard of plenty, I reccomend you stop using it. Try using the xitami server, it has an http server as well as an ftp server. Its secure and only a handful of exploits have ever been discovered for it. And as for hijacking servers, I would say, find a way to contain the damage, and then let them do it, get all the software you can, wait about 2 days to see if they upload anymore to you and then cut them off with a reinstalled firewall. Make sure to uninstall serv-u. It just isn't that secure.