Viruses, Trojans and worms, oh my!
By Charles Miller

The email I receive from Atención readers tells me there continues to be a lot of confusion over the various categories of computer pests. I refer to viruses, Trojans, worms, browser hijackers, spyware and adware.

There is some confusion and difference of opinion as to how these should be classified. I personally segregate all of these into three rather broad categories. Other writers will have different ideas for how to explain these but here comes my attempt.

First: Viruses, Trojans and worms I consider to be real troublemakers. These rogue programs invade your computer, can cause damage and replicate themselves from computer to computer to spread their damage to other computer users.

The computer virus is a self-replicating program that usually causes the user a problem to one degree or another. Some destroy your data, others are just a nuisance.

A Trojan is a cousin of the virus, but usually requires a gullible or uninformed user to make the mistake of activating the Trojan. Trojans do not self-activate.

Worms are self-replicating programs that clog up your computer and the internet, but are generally not destructive of your data.

Second: Browser hijackers. In the same family as the Trojans, it again requires the uninformed user to install its code, after which the program takes over your internet browser (usually Microsoft Internet Explorer). From that point on, the hijacker is in control of what you see on the internet, where you can go and what advertising you are sent.

Aside from the censorship issues, browser hijackers are known to cause problems with your internet connection. Browser hijackers do not self-replicate in order to infect other computers, but like a bad case of the flu they are hard to get rid of.

The main purpose of a browser hijacker is to control the advertising you see as you browse the internet.

Third: Spyware and Adware. These two are the least pernicious of the pests by virtue of the fact they are the least dangerous. That does not mean they are completely benign because these can really cripple an older computer without the memory and processor power needed to handle the extra computing demands created by these pests.

Spyware, as its name implies, spies on your Internet surfing habits attempting to learn your probable buying habits. If you surf a lot of medical sites, you get ads for drugs. If you surf lots of financial sites, you get ads for credit cards and home mortgages, etc. I probably do not need to say this, but I will do so anyway: If you surf any pornographic sites, prepare to be absolutely inundated with ads for more porn.

Adware works the same way, but is often hard-wired for one particular type of ad being sent to you. Drug companies, financial institutions and porn sites are all frequent users of the adware programs. The intention of the adware program is not to wreck your computer, but rather to control what types of advertising you are sent via the internet.

So, there you have this writer’s three broad categories of computer pests. My hope is that this will help many readers to better understand the distinctions between these rogue programs.

It is becoming more accepted to refer to all of the above as “malware.” This umbrella term refers to any software installed without the informed consent of the user.

Charles Miller is a freelance computer consultant, a frequent visitor to San Miguel since 1981 and now practically a full-time resident. He may be contacted at 044-415-101-8528 or email FAQ@SMAguru.com.
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