Trojan Horse is Not Virus!

Strickly speaking, a trojan horse is NOT a virus because it does not replicate like ordinary viruses do. A trojan horse is an unfriendly program which will appear to be something other than what it is, for example a program that is disguised as a legitimate software program.

Below are some common trojans:

Back Orifice 2000 : BO2K allows outsiders to access and modify any information on a Windows 95, 98 and NT machines through an invisible server program installed by the program. It also allows outsiders to spy on what user is doing. BO2K is expected to be released on 10/7/1999. Users are advised not to run executables from un-secured source and updates their antivirus tools periodically.

http://ntbugtraq.ntadvice.com/bo2000.asp

Back Orifice: This trojan horse allows an intruder to monitor and tamper with Windows 95 and Windows 98 computers over the Internet. There is no easy way for a computer user to know the attack is taking place, and there is no easy way to stop the attack once Back Orifice has installed itself on the computer. The ver 1.2 of Back Orifice cannot be installed on Windows NT system. Click here for details.

NetBus: NetBus is a remote administration tool, much like the infamous Back Orifice tool. However, Netbus predates Back Orifice by several months and is also capable of working under Windows NT in addition to Windows 95 and 98. Click here for details.