Overview of Anti-Virus Technology

Viruses are one of the most serious threats to computers today. This threat grows when a computer is placed on a local network or is connected to the Internet. Safe computing practices require some protection against viruses.

Viruses Defined:
Although almost everybody knows about viruses through the media or other stories, many myths exist about viruses because of the incomplete coverage and sometimes misleading information presented on viruses. Viruses are computer programs, but unlike normal programs (Microsoft Word, Mozilla, QuickTime, etc.) the main purpose of a virus is to damage a computer or the data it contains. Since viruses are programs, they must be run just like any other computer program. Because of this need, the first thing a computer virus needs to do is to place itself where it can be run by a computer user. There are several, common places a virus can "hide":

  • Inside another program: Viruses will embed themselves inside another program, allowing themselves to be run when the computer's user runs the program to write their thesis or do any other common task.
  • On the boot sector: The boot sector is a special part of the computer's hard drive and bootable floppies that contains a special program that boots the computer. A virus can place itself in this location, and will then run every time a computer is started. This method is not as common as the first method.
  • Inside a data file: Some programs (Microsoft Word, Microsoft Excel, etc.) allow programs to be stored inside the documents they open. These special programs are called macros. Macro viruses put themselves inside the document files of programs and the program will run them when the document is opened. Note that this is only true if the program allows macros to be stored in the data files it uses. If a program does not support macros, a virus cannot hide in the data file, although a virus using another method could damage any data file.
  • Java Applets and ActiveX Controls: These two types of files are small programs that can be associated with web pages, and are then run when someone views the web page they are part of.
How dangerous are viruses?
Any virus is dangerous because the main intent of the virus is to cause damage. Nonetheless, some viruses are more destructive than others and easier to become infected with. Viruses like Michelangelo are very destructive (they erase all data on a hard drive) but run only on a certain date or when a certain event happens. Other viruses are just nuisances. Basically, the threat of a virus depends on what it was programmed to do. It is best to consider all viruses equally dangerous and work to prevent against any of them infecting your computer.

What do I do to prevent my computer from becoming infected?
The best protection against viruses is simply being careful. If you can, only install programs from CD or that have been downloaded directly from the company that wrote the program. Even with this precaution, an anti-virus program is highly recommended. Even major computer software publishers can accidentally release viruses with their software (IBM accidentally released update disks with the CIH virus a few years ago). Several free scanners exist and several more well-known ones can be purchased. While these programs cannot always protect you from the newest viruses, they are the best defense against viruses. Anti-virus programs, along with careful habits will give you the best protection against viruses that exists today.