Trojans are malicious applications that pose themselves as legitimate software in order to trick users to install them. Once on the victim's machine, it may run any number of malicious process to steal vital information or inflict damage to other software.
This is a hidden (hacker's) remote administration utility similar to the known Backdoor.BO (aka Back Orifice Trojan) trojan. Also known as Phase Server. It allows to administrate infected computers from a remote console, to steal files, to damage installed software, upload/download/execute files, change/list/create/remove directory, copy/move/rename/delete file, lockup server, crash server, create/delete/read/modify registry key.