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What
is a Computer Virus? (The following is adopted from "A Guide to the Educational Support Personnel Information System," published in print and on the Web by the National Education Association.) You've probably heard a lot about mysterious computer "viruses" that can wreak havoc on the computers of unsuspecting victims. Actually, the risk of your computer being attacked by a virus has been somewhat overblown. When there's something wrong with you and the doctor doesn't know what it is, she often tells you that you're suffering from a "virus." Likewise, many computer users are quick to cry "virus" when an unexplained problem arises with their computer, even though the problem may actually have been a software glitch, a power surge, or the cat walking across the keyboard when no one was looking. The single leading cause of computer data loss is human error, not viruses. But computer viruses are real, and do cause problems. Think of them as social diseases of computers. Luckily, if you are armed with an elementary understanding of how viruses work, and exercise basic computer hygiene, you should avoid ever having a virus problem. (For an interesting, if opinionated, explanation and debunking of viruses, check out the Computer Virus Myths Home Page. Computer viruses are parasitic programs which are designed to alter the way your computer operates without your permission. They incorporate themselves within, or "infect," executable program files (programs that can be run on your computer). Since it is possible to put strings of program commands (called "macros") in certain kinds of data files (like Microsoft Word document (.doc) files), these files can also be infected with viruses. So far, viruses have been found in MS-Word (.doc) and MS-Excel (.xls) files. Other types of viruses attach themselves to boot records, which contain information your computer needs to start. Thousands of different viruses have been identified. Viruses are activated when you run the program they are hiding in, or, in the case of boot viruses, when you try to start ("boot") your computer from a hard drive or floppy disk containing the boot virus. At this point they can spread by reproducing and infecting other program files. Most viruses are merely annoying pranks. For instance, the "Tea Time" virus interferes with keyboard input between 3:00 and 3:13 every day. But some viruses are designed to corrupt or destroy files on your computer, or even, in the case of boot viruses, preventing your computer from starting up. Once a virus has infected a file in your computer, turning off the computer will not eliminate the virus. Viruses will not infect hardware, they only corrupt software. This means that you can't spread a virus by, for instance, changing a keyboard from one computer to another. Also, viruses cannot infect most kinds of data files, including text only files (such as e-mail), and graphic files. However, viruses have been developed which infect MS-Word and Excel files. Also, it is possible for a file to be maliciously mislabeled. For instance, Rich Text Format (.rtf) word processing files don't carry viruses. However, it is easy to label an infected Word document (.doc) file as an innocent-seeming RTF file, which an unsuspecting user might then open without scanning it for viruses. How Your Computer Can Catch a Virus The only way that your computer will be affected by a virus is if a virus-infected file is introduced into your computer system. This file can be brought in through a floppy disk, through your modem, or through a network connection (if your computer is part of a network). So you can't get a virus by a typing mistake, by taking part in an on-line chat room, or, in general, by reading your e-mail. (You can, however, get a virus by running a program file that is attached to an e-mail message.) Until very recently, it was possible to say categorically that it was not possible to get a virus by simply reading E-mail. Now, however, a new type of virus has been developed (bred?) which can be carried in the body of an E-mail message. "Bubbleboy" is the first of these viruses. It only affects users of Microsoft Internet Explorer 4 and 5, and Outlook Express or Outlook E-mail. (For more about Bubbleboy, see Helpnet's Current Virus and Security Issues.) Now that you know this, there are a few steps you can take to avoid virus problems. Here are some basic precautions which will minimize your risk of virus infection:
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Go to "How to Tell Virus Fact From Virus
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