What is a virus?

Yeah, I had to start somewhere. The definition of a virus is an illegal piece of code that can replicate itself. They often do damage, but they don't have to in order to be a virus. While I'm here, I'll explain trojan horses, worms, spyware, and adware (just naming the basics as of right now).


Trojan horse- A seemingly useful program that, when executed, wreaks havoc in your system. Say you saw a really nice game that you would like to download. It looks awesome, with all the most cutting edge 2-D cruddy graphics, complete with a chatroom. You download it, and execute it. As you're playing the game, a part of the game sneaks out and plants itself into your computer, planting registry keys as well. You get off the game, unaware of anything but what was said in that chatroom, and the computer is left alone. The "evil" part of the game sends out a message to the infected files, signaling to destroy them. Suddenly, you get a message onscreen.


It reads...









You hastily click NO. A reply from Mr.Virus comes up.


It reads...








Suddenly, you see a black screen. A little popup comes up. It says "LOL, we got you. Oh yeah, we looked in your cookies and found your credit card number. We'll use it to buy a plasma screen!"

(That was a scenario by me, so your probably not going to get these messages. But Trojan Horses are that dangerous. Be cautious of the stuf you download, and stuff that decides to dowload to your computer without your consent.)



Worm- A file that can replicate itself, mainly to take up a lot of space on a disk or network, and can eventually crash a the target. Here is a real example:

The Melissa: FAround March 26, 1999, a computer programmer wanted to crash the internet mailing system. He created an email with a list of passwords to 80 adult rated sites, also creating a macro within the email. The macro went and found the first 50 people in the recievers mailing list, and mailed itself to them. These emails repeated this process over and over again. After the Melissa worms duplicated 10 times, there would be already 97,656,250,000,000,000 copies of this email. Obviously, this puts a lot of stress on a mailing server, killing it. What's even more dangerous, is that the Melissa has four "evil twins". The Melissa.U, Melissa.V, Melissa.W and Melissa.AO are designed to mass mail themself also, but also stripping archives of their properties, and corrupting system files. Also, some of these displays the message "Hint: Get Norton 2000 not McAfee 4.02". (personally, I don't use either.)



Spyware and Adware are responsible for slowing the system down, and popups. Also, they can hijack your browser and take you to any site they please. They just run in the background, stealing your information as you type it out on a registration form, or advertising something you don't want. To make a long story short, they are annoying.

That's the basics of malicious software.