Everything You Always Wanted to Know About Computer Viruses (But Were Afraid to Ask)

By: Jim Fisher

Computer viruses can be rather enigmatic to anyone who is less computer savvy than the "IT guy" at your office or the computer whiz-kid who always seems to get picked last for teams in gym class. If you fall outside that demographical slice of the population, then there's a good chance that you may have a few questions about computer viruses, how they'll affect your life and what you need to do to protect them. With that in mind, let's open the floor to questions…

What is a computer virus?

Strictly speaking, a computer virus is a program that, once run, can copy itself and infect other programs and files on a computer. In practical discussions, computer worms and Trojan horses are also lumped into the same category as viruses. Worms are self-replicating programs that can infect a network without any need for action by an end-user, often via e-mail. Trojan horses are computer programs that appear to be legitimate pieces of software, but in reality house hidden software that performs another function.

Any of these programs can be completely innocuous to your system, but on the other hand they can be extremely dangerous. Nastier viruses and worms will delete files and corrupt your computer to a point where it can cease to function. Trojans can collect personal data and transmit it to the program's author or to a web page somewhere. This can be a scary concept, especially if you have your credit card number, social security number, financial records and other personal data stored on your computer. Trojans can also relay spam e-mail without your knowledge, upload and download files, take screenshots and enable others to gain remote access to your PC.

I've also heard of Spyware and Adware?

Yup. Those are bad too. Both are generally types of Trojans, although that isn't always the case. They are generally bundled with some sort of free software, especially file sharing and "Internet accelerator" programs.

Spyware runs invisibly on your computer and can transmit data to a third party. It is often used to track your web browsing habits. This data is then funneled to advertisers to better target spam campaigns to suit your habits. Spyware can also log keystrokes and scan your hard disk for personal information.

Adware is very similar to Spyware in terms of delivery and functionality. It generally refers to software that causes advertisements to randomly pop up in web browser windows. Adware is used as a source of revenue for its authors, who are generally paid by based on the number of times an advertisement is viewed by end users. Some web pages do have legitimate "pop-up" ads that might be mistaken for Adware at first glance. However, if you are seeing a large number of these advertisements popping up on your screen there is a good chance that you have some sort of Adware on your system.

This is kind of scary. Can I do anything about this to protect myself?

Yes, there are several steps you can take to help shield your computer from all these nasty programs that are running around.

Get yourself an Internet router with an integrated firewall. Not only will this little device allow you to share your Internet connection among several computers in your household, its firewall will help to keep intruders out of your system.

Make sure that your copy of Windows is up to date. This patches the known security holes in the program that Microsoft has fixed.

Stop using Internet Explorer for web browsing. Immediately. Go to http://www.mozilla.org/ and download Firefox. This web browser is much less prone to attacks: and it's free.

You should also get some sort of Antivirus or Internet Security software. Even the most basic packages will protect against viruses, spyware, adware, worms and trojans. More advanced suites will add e-mail filtering, anti-phishing tools, spam protection and a software firewall to the mix.

What if I have a Mac? The "I'm a Mac" guy on TV tells me that they don't have viruses.

He's mostly right, but there is some marketing spin in there. While there are currently no viruses running around in the wild that target OS X, some authors have developed "proof of concept" programs that can attack Macs. These programs function differently than PC viruses, often requiring you to enter your administrator password to run them.

Mac users should regularly check software update to ensure that they have the latest security patches applied. Enabling the built-in software firewall in OS X, found in Sharing Preference Pane, is a good idea. Mac users should also add an Internet router with firewall to their network. An ounce of prevention is worth a pound of cure, after all.

Is there anything else I should know?

If you do end up with a virus or similar program on your computer, don't panic. Let your antivirus software take care of it. Don't open e-mail attachments from strangers. If you get an attachment that appears to be from a friend and looks suspicious, talk to the person or use an antivirus application to scan the file before opening; it could easily be a worm.

Most importantly, use some common sense when on the Internet. You wouldn't trust a stranger on the street to give you a drink of water, and you wouldn't tell them your credit card number or online banking password. Don't open files that look suspicious, and don't offer personal information to someone claiming to be from your bank, PayPal or eBay. A modicum amount of precaution will go a long way in protecting your computer.

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