Virus Basics

Viruses

You hear a lot about viruses these days and you may be – understandably – concerned and confused. Should you be worried about them? Is your computer protected? What is a virus anyway? And, are they even that big of a problem?

What is a virus?

There are many types of computer viruses ("worms," "trojan horses," "macros," etc.), but at its simplest, a virus is any program that makes copies of itself on other computers without permission.

Many viruses are relatively benign, and their main effect is to cause odd behavior on the infected computer (causing strange messages to appear, not letting the user close windows, etc.). These viruses usually don't cause irreparable harm to a computer, but they are still a distraction and a waste of time and resources to fix. One of the main reasons this type of virus is created is to give the cracker (a "bad" hacker, or computer programmer) notoriety. The cracker thinks they are showing how clever they are by infecting as many computers as possible, and, of course, receiving the accompanying headlines in the news.

Other viruses are downright malicious, whose purpose is to damage data or make computers unusable. These crackers often target a particular program, software company or type of technology that they have a grudge against. These are the type of viruses that you hear about on the news, such as the "Nimda" and "Melissa" viruses.

How are they spread?

Sharing Files: The original viruses were typically spread by the sharing of floppy disks (floppies). Somebody would copy a file from an infected computer to a floppy, use the floppy to copy the file to another computer, and then run the file on that other computer, thereby infecting it. The use of floppies has dropped, but transferring files – and viruses – still occurs – it's just typically done through the use of CDs, Zip drives, shared network drives, or file download areas of websites.

E-mail: This is how most of the viruses you hear about nowadays are spread. The virus is placed into an e-mail message that is sent to others. If someone who receives the virus e-mail opens it (or even previews it), the virus installs itself on the new computer. Once the virus is installed on the new computer, it then often emails itself to email addresses it finds in the email program's address book. One of the reasons this type of e-mail spreads so quickly is that the recipient usually knows the person who (unknowingly) sent them the infected e-mail, so they think the email message is safe to open. And, since many people have their email program set up to send and receive new messages automatically, the infected computer may send hundreds of infected emails before the user discovers that the computer has a virus. (One VERY good reason to not use the automatic send and receive option!).

Websites: Another way viruses spread is by simply opening an infected web page with your web browser or downloading an infected file onto your computer (as was mentioned above under the "sharing files" section).

How do you protect yourself?

Backups: This is just good computer practice anyway. The manner in which your data is destroyed – be it virus, a failing hard drive, or just accidentally deleting the wrong file – isn't the issue. What does matter is that you have a recent backup of the data that you can use after fixing the problem that destroyed the data in the first place.

"Safe Computing": This is a term taken from the world of biological infections. The idea here is to only share data (email, files, or even browsing the web) in known, safe situations. This applies to everything from copying floppies that came from questionable computers, to downloading files from unknown websites, to opening e-mail that came from unknown people or have suspicious or unexpected subject lines or attachments. The point is to avoid exposing your computer to viruses in the first place. So, if you don't share data with anybody whatsoever then you'll be completely safe. Of course, this largely defeats the purpose of computers in the first place, because sharing data is one of the primary things we all do with them.

Disable Susceptible Features: This means turning off, or otherwise restricting, many of the automatic things that computers do. Unfortunately, this also means giving up some of the most useful capabilities of your computer. 

For example, Microsoft's e-mail program, Outlook, is regularly hit by viruses. Part of the reason for this is that it has a lot of cool automatic capabilities built into it, including the ability to run programs that are embedded in e-mail messages. Microsoft has a security "update" for Outlook that essentially locks down all of its vulnerable features. I installed this security update once – for about one day. Then I removed it (no small feat in itself), because it made reading and using my e-mail extremely tedious.

For example, I could no longer directly open any files that were attached to a message. I had to first save the file to my hard drive, then open the file from the hard drive. Although this isn't terribly difficult or time consuming, it does get very tiresome and irritating if you have very many files emailed to you.

Web browsers (Internet Explorer and Netscape Navigator) are another kind of software that viruses take advantage of by exploiting the very features that make them useful. Many web pages use the capability of web browsers to run Java programs, "plug-ins," or ActiveX controls to do the cool, interactive, useful, or just plain fun things we've come to expect from a website. But, to make your web browser extremely safe from viruses, you could turn off its Java, plug-in and ActiveX capabilities. Of course, doing so also means that you can't use a lot of websites.

Anti-Virus Software

The final and most complete way to protect yourself is to install anti-virus software, which actively monitors everything that occurs on your computer. Keep in mind, however, that anti-virus programs are not a substitute for creating regular backups and practicing (relatively) safe computing in the first place.

How anti-virus programs work and how to use them deserves an article all by itself, so I'll describe how they work in next month's column.