Pin Me

What Is a Computer Worm?

written by: Lee Clemmer•edited by: Bill Bunter•updated: 5/5/2010

We hear that our computer security is threatened by computer viruses and computer worms. But what is a worm, exactly? How is it different from a virus or a trojan? This article demystifies computer worms so you can protect yourself.

  • slide 1 of 3

    Different Kinds of Computer Threats

    There are several different kinds of computer infection. Experts and journalists come up with colorful names to describe them. A computer virus spreads from computer to computer much like an outbreak of influenza; hence its name. There are other categories of malicious computer software as well. Sometimes we categorize them all as "viruses". The proper term we use now for all these types of software is malware. Included in malware are viruses, trojans, root kits, and worms. There are other subcategories, and occasionally the software may even have a legitimate use. The thing to remember is that almost all the time when we're talking about this type of software, it is unwanted by the owners of the computers and networks it's on. So what makes a worm a worm?

  • slide 2 of 3

    Why Is it Called a Worm?

    We already had the name virus. It was catchy and descriptive. When many computers are networked malicious programs can search the network for vulnerable systems, take over the system, use the resources of that computer to search for others and spread out from there. That sounds a lot like how a worm spreads from one piece of fruit to another. Not all worms work in exactly the same way, and not all spread at the same rate. However, they all search a network for uninfected systems, move there, and repeat the process. Some worms engage in other destructive behavior on the systems they infect, and they clog up networks, using up valuable bandwidth. Sobig, MyDoom and Conficker were some widespread recent worms.

  • slide 3 of 3

    Protecting Yourself From Worms

    Good current anti-virus, security protection software, along with network firewalls or personal firewalls will provide excellent protection against worms. Just be sure to keep the software updated. This is what we mean by updating your virus or malware descriptions. Other things to keep in mind to protect yourself--and these are good ideas any time:

    Don't click on a link if you don't know what it is.

    Don't run or install a program if you don't know what it is and trust the source.

    Don't just click OK without understanding what you're agreeing to.

    Now you have a better idea what a worm is and how it propagates. For more help staying safe online, check out my article The Top 5 Security Mistakes People Make when Browsing the Web and How to Protect Against the Conficker Worm.