What is a "Trojan horse"?
A Trojan horse is a disguise for a virus, a worm, or some other application to enter your system. So, it's usually disguised as something you would accept into your computer, whether it's some sort of little piece of software, a game, or something like that. That's the disguise. Inside it, is some kind of virus, worm, or application that is going to potentially wreak havoc on your computer. By accepting a Trojan horse, you're inviting a potentially damaging situation into your computer or your network environment. The Trojan horse, again, is the package that looks familiar, friendly, and desirable, that contains the virus or the worm. Anything that you bring into your network, or your computer, could lead from anything to mischievous type behaviour (like emails being sent out, address books being deleted, or files being replicated or deleted) to really hardcore stuff, like files missing, system information missing, network information starting to go down, networks being taken down, and machines being taken down. You really have to be very careful about what you allow to enter your computer or your network environment. Some viruses and worms, particularly those brought in by a Trojan horse (which can really hide a lot of what it's intended to do) can do some pretty significant things, such as install back doors into servers and computers. A back door is basically an entryway for a hacker or someone to gain entry into a server network or a computer. It can embed a piece of software that captures your keystrokes, so it can measure what you're typing and even capture your password information, your personal info, and your login information. Since it's coming in the package of a Trojan horse, something that's either familiar or acceptable, it can pack a lot more into it. It can do some really damaging stuff.
