Computer worms are different from viruses as they are not usually created or distributed with the intention of harming individual computers. Worms work to cause damage to computer networks but they can only do this by traveling through networks via individual computers that do not have up-to-date security software installed. Without current security, a computer can be infected with a worm through everyday activities without knowing it and then pass that worm through the network they are working on or in.

Here is a brief list of the more common and troublesome computer worms:

Beagle (AKA Bagle)
The Beagle worm attacks computers and affects versions of Microsoft Windows. The first version of this worm began and ended in January 2004. It was not a widespread worm, nor did it cause a great deal of damage. The worm appeared again in February 2004. This version caused a bit more damage. Several versions of this worm have appeared since but none of them have been very successful in spreading or causing harm.

I Love YOU Worm
Spread in 2000 through an email, the I Love You worm counted on individuals opening the email because of the subject line. Over 50 million infections were reported in the spring of 2000, and the US Pentagon and CIA shut down their email in order to make sure the threat of outsiders breaking into the email systems was covered. Event he British Parliament shut down their email systems.

Lovesan (AKA Blaster)
Created by Jeffery Parson of Minnesota who was 18 at the time, the Lovesan worm spread rapidly in August of 2003. The worm contained two messages that were displayed after it had successfully attacked and infected a computer. The first message was simply: “I just want to say LOVE YOU SAN!!”. The second message was directed towards Bill Gates: “billy gates why do you make this possible? Stop making money and fix your software!!”

Nimda
This worm was spread through mass emails and then copied itself and continued to spread through a variety of methods. In just 22 minutes, Nimda “became the Internet’s most widespread worm”. The name is the abbreviation “admin” spelled in reverse.

Slammer
This worm moved fast and wrecked havoc with the internet in January of 2003. It infected so many computers and networks in such a short period of time that some countries thought they were being attacked.

Sasser
This worm also affects computers running with a Microsoft system. Specifically it targets Windows XP and Windows 2000. It spreads rapidly but is easily stopped by a firewall or by updating your user system