"If you have your health, you have everything. If you don't, you have nothing."
That piece of folk wisdom works as well for computers. When they get infected with nasty programs like viruses, they cease to be our more-or-less reliable servants. The result can be anything from the loss of family photos to the broadcasting of personal financial information across the internet.
What is a computer virus?
A virus is essentially a package of instructions delivered to an organism that then uses the resources of that organism. In order for the virus to survive and spread, those instructions have to include a way for the virus to reproduce itself and spread to other organisms.
Unlike a biological virus, a computer virus has to be created by a person. The motive for building a virus varies from the merely selfish (demonstrating the author's skills) to the truly nasty (bringing down an enemy's web site or turning thousands of computers into zombies ready to execute the author's commands). An infected machine can even pass on personal information to others (causing embarrassment) or send it to a thief (opening up the possibility of identity theft).
How can I catch a computer virus?
There are four general sources of infection: email, web pages, downloads, and portable media (removeable disks). By far the most common is email.
Once upon a time, email was simply text messaging. Then we learned how to affix an attachment to our messages, and suddenly all kinds of programs, pictures, documents, spreadsheets, presentations, screensavers, music and other files could hitch a ride into our inboxes. Not all of this is good.
It's one thing if all the attachments are what they say they are. But you can't count on it. A file claiming to be a screen saver can actually contain instructions to delete picture files. A "free game" can trash your hard drive (on purpose). An HTML message can steal your credit card information. Even a data file like a Word document can contain instructions to be activated when Microsoft Word is started to view the document. The possibilities seem unlimited, particularly for computers running some version of Windows.
Although email is by far the most likely source, viruses can also come from visiting web pages with malicious code embedded in them, from downloads of files that have been infected, and even from portable media shared among computer users.
So how do I avoid a computer virus?
The single biggest thing you can do is to run something besides Windows. Seriously. The vast majority of viruses are written for Windows systems. But if that's not an option.
The first step is not to open email attachments, including HTML. Of course that includes not clicking on the attachments, but it also means not having your email program set up to automatically open or load your attachments "for your convenience". The virus doesn't care who starts it.
The second step is to get a reliable piece of antivirus software and get it configured properly on your computer. That means your antivirus program not only scans your email, it also scans your file downloads and anything else you point it at - like removeable media that's been passed around from one person to another. It also means your antivirus program gets updated frequently. (Otherwise it's like the window screen with little and big holes - little holes to keep out the little bugs and big holes to keep out the big bugs. You can guess how well that works.)
These two steps together can prevent the vast majority of virus infections. Then add in a little caution when surfing web pages: stay away from web sites mentioned in spam, and consider using a browser other than Internet Explorer.
There are more things that can be done, such as using a proxy when web surfing. Although easy to use once it has been installed, proxy software and other measures are best installed by someone who is technically proficient.
How do I repair the damage from a computer virus?
If you are comfortable with your antivirus software, start there. Most antivirus software has options for scanning, quarantining, and cleaning.
Scanning refers to a review of your entire system by the antivirus software (freshly updated, of course!) to look for signs of a virus. You should scan your system regularly. Schedule a full system scan during some time when the computer is on but not likely to be in use and let it run automatically.
Quarantining refers to segregating a potentially malicious piece of code so that it cannot reach the rest of your system. If a scan of your system finds a virus, this is one of the things your antivirus software does for you.
Cleaning may also be called disinfecting, and it refers to removing the malicious code from your system, particularly from places where it might be hiding inside otherwise good files. This is another thing your antivirus software can do for you. If you get a message that the cleaning was not successful, it's time to bring in a knowledgable person to clean things up for you.
If you do catch a computer virus, it's a smart idea to try to figure out where your defenses were breached and make whatever changes are appropriate to keep it from happening again. Your computer health is important.
by Evelyne Stalzer
