A computer virus is a software program which must attach itself to another program in order to replicate itself. In this way it is a parasite very similar to a traditional virus, such as the kind that give us colds every year. A computer worm, on the other hand, can be self-sustaining and self-replicating, it does not need any other program in order to recreate itself over and over. Both can have potentially devastating effects.
The most common mode of entry for a harmful computer worm to get into your computer is through your e-mail, which means this is the place to start working in your attempts to keep them off your machine. One thing you might consider is to use a web-based email service, such as Microsoft’s Hotmail, Yahoo! Mail or Google’s gMail, as it is more difficult for a worm to infect your computer through a web-based email program than it is through more traditional email software such as Microsoft’s Outlook Express.
When you are reading through your e-mails, watch out for attachments because it is through the attachment that the worm will most likely come. Essentially an attachment is any addendum to your e-mail message that is not just text: it could be an html file, it could be a picture, it could be a movie, it could be a program.
Programs, generally ending with the extension .exe, are the most dangerous forms of attachment. Unless you are receiving something from someone you know (and even then it can be dangerous), it is best not to download program files, as they are the perfect haven through which to transport a computer worm. If an attachment looks strange or out of the ordinary, don’t download it onto your computer, even if its from someone you already know: many e-mail worms are designed to send themselves to everyone in a person’s address book once it has established itself on a computer, meaning it could have been sent to you from your best friend but they didn’t know it was sent: the worm did it.
What happens if you already have a worm on your computer? The first thing to do is shut down any programs that you have running. This will minimize the ability of the worm to get into your programs. If you found the worm through an anti-virus program or a worm remover (which is always a good thing to have), it should have a method for quarantining and/or removing the worm from your computer.
If you don’t have such a program, you’re going to need to get one. If it is possible, download a program from an alternate computer, then run it on your infected computer through a disk: this will minimize the possibility of the anti-virus program being infected as well. If that isn’t possible, just download it to your infected machine and run it right away. Try not to reboot the machine after the worm has been found: that could just allow it to entrench itself even deeper.