How do computer viruses work and what are they

What Are Viruses and How Do They Work?

As the number of people using computers grows, so does the number of viruses and the ease with which they are spread. If the names Anna Kournikova, the Magistr, Code Red, Nimda, Sircam, My Doom, NetSky, and Bagel.z do not mean anything, they should - they were all viruses that affected and wreaked havoc on personal and company computers in the past few years.

First, computer viruses are not real viruses, but a metaphor for a serious problem. A computer virus is a program that makes copies of itself and infects diskettes or files. Viruses can spread to other computers and files whenever infected diskettes or files are exchanged. Often infected files come as email attachments - even from people you know. Often, the email sender has no idea that he or she has passed on a file with a virus in it.

Some computer viruses can erase or change the information stored on your computer, while others may do little or no harm to your computer system. According to CERT, the Carnegie Mellon University virusmonitoring center, more than 82,000 incidents of separate viruses were reported in 2002, more than double the amount from the previous year. And that number continues to skyrocket; Carnegie Mellon reported more than 137,000 incidents in 2003.

A computer virus is a program that can "infect" other programs by modifying them to change how your computer operates. Viruses can spread themselves without your knowledge or permission on your computer or to potentially large numbers of programs on many machines. Unlike most other programs, viruses are specifically designed to spread themselves and they can without your knowledge. A virus program can contain instructions on when or how to activate. Several of the worst viruses have triggered on a specific calendar date.

One way to protect your computer is to run an anti-virus program, which scans your hard drive looking for signs of these viruses. The way you get a virus on your computer is to accidentally run a program that already contains the virus.

Do I Really Need an Anti-Virus Program?

Yes. If you limit your activities to commercial software and to programs you download from places that have credibility on the 'Net, you may never encounter a virus. That is the exception. If you work on a network of computers where people regularly use their own floppy disks, like at a school, or you have questions over who might have access to that computer, then an anti-virus program is a smart investment. Viruses have been known to display messages, erase files, scramble data on your hard drive, cause your computer screen to behave differently, and some have prevented computers from starting up.

Many viruses do nothing obvious at all except spread! You cannot rely on strange behavior as an indication that you have a virus. The most reliable way to find viruses is to use competent anti-virus software. The rule you should live by is if anyone else ever touches your computer, connects to your computer or sends you email, you should have a virus checker and make sure it is the most up-todate version available.

How Can I Protect My Data?

Viruses are a threat, but data loss can also occur from other factors, usually mechanical failures. If you have files you cannot afford to lose, make sure you have more than one copy of them. The best way to do that is to copy hard disk files to disk/tape with a reliable backup utility program. You should also create an emergency boot disk, and keep it with your backup disks/tapes in a safe place, with write-protect tabs secured.

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