Wanted? Computer Virus, Armed and Dangerous

Are you running an anti-virus program on your home computer? If so, you've likely heard that to keep it functioning properly you need to update your virus definitions regularly. Today on Common Sense Computing, we are talking about what virus definitions are and how they are used to protect your computer.

You can think of a virus definition like a wanted poster. A wanted poster usually has a picture of the fugitive and a detailed description of their crimes and how to recognize them if you see them. You know - 5 foot 11, blond hair, scar over the right eye.

Similarly, a virus definition tells how to recognize a specific virus or worm when you see it. For example, it might say to look for emails with a particular subject line or an executable program with a particular name or a file that contains a specific pattern of data.

Anti-virus programs use these virus definitions in two major ways. First, much like a police blockade, they can check all incoming and outgoing files against the list of wanted fugitives. Second, much like a house-to-house search, they can scan your entire computer checking all the files.

The "police blockade" method is essential for preventing new attacks that arrive via email attachments or web downloads. While house-to-house search is a more time-consuming activity that that is done periodically to catch any fugitives that have slipped around the blockade.

Now, it is probably pretty clear why keeping your virus definitions up-to-date is so important. Just imagine how effective, the police would be at preventing crime, if they were using wanted posted from the 1970s. They would never catch the currently active criminals, right? The same is true on your computer. You can run the best anti-virus program in the world but it will still let the nastiest new viruses go right on in if you don't have your virus definitions up-to-date!

So when you get home, you might want to check if your virus definitions are up-to-date and while you are at it you might want to visit us on the web at www.commonsensecomputing.org. For Common Sense Computing, this is Jeanna Matthews.