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For Computers, Flu Season Lasts All YearReporting on computer "viruses" is a popular way to sell newspapers these days. Even people who aren't involved in the computer industry have heard of computer viruses and what they can do to computers and networks. While much of this information is accurate, some is exaggerated, misleading, or just plain incorrect. Still, in order to protect your work, it is important to understand what viruses are, how they spread, what they do, and how to avoid them. Many people would consider a computer virus to be any program that does something "bad" to the computer or network. As you can imagine, this isn't technically accurate. What the popular press may refer to as a "virus" can be one of three things: an actual virus, a Trojan horse, or a worm. Some recent "virus" programs have actually been combinations of those three types. True viruses infect other programs or files on the same computer, but do not incorporate any methods of distribution. They rely on human intervention to spread. Most Microsoft Office macro viruses are true viruses. Trojan horses, named after the mythical wooden horse used in the Trojan War, are malicious programs disguised as legitimate ones. These dangerous programs may look like games or other harmless software, but underneath the bland exteriors there are hidden instructions that can do many different types of damage. Once again, Trojan horses require human intervention to spread. Worms, on the other hand, are able to spread on their own by using networks. The recent Loveletter "virus" was actually a worm, and Melissa was both a worm and a virus. Because there are now so many hybrid programs and the methods used to protect against all three types are so similar, we will continue the popular practice of calling all of these programs "viruses." There is one type of program that causes "bad" results that is not a type of virus. This type of program is one that has a "bug" in it. Unlike a virus-type program, a bug is almost always the result of simple programmer error. This might cause a program not to work at all, generate spurious answers, or conflict with other installed programs. Contrary to some news reports, the Y2K problem was not a virus; it was actually a very common bug. Since there is little you can do to avoid getting buggy software, and since fixing problems caused by bugs is not an easy task, we will not include bugs in the term "viruses." Possible virus effectsSome viruses have visible symptoms, such as pop-up windows or altered displays, but some do not. In fact, some seem to exist only to spread themselves to other computers. A few viruses will stay "dormant" (not do anything) until a certain trigger date arrives or event occurs. Microsoft Office macro viruses will sometimes make your Office programs behave erratically, such as not allowing you to save a document except as a template. Worms can have a severe impact on computer networks. The major problem the Melissa and Loveletter viruses created was the volume of spurious e-mail they produced. They overloaded networks, which then couldn't handle the delivery of regular mail. Many companies that use e-mail systems to conduct business lost an important avenue of communication, not to mention the number of person-hours required to clean up the mail systems. Long-term consequences of viruses can vary. Many viruses leave no residual damage at all. However, there are also quite a few that can create serious problems. Some macro viruses corrupt Office files. The chances of recovery can range from complete to incomplete to not at all. More seriously, some viruses don't limit themselves to just a few types of files. They can affect all of your information by deleting system files, programs, and documents or even re-formatting (completely erasing) your hard drive. Data recovery from this type of virus can be extremely difficult or even impossible. This is one reason to make sure you always have an up-to-date backup (see story "Oh No, Where Did it Go?" on the next page). There are some things that a computer virus can't do. No known virus damages computer hardware. This means that a virus can't make your monitor explode, ruin your sound card or speakers, or otherwise harm your keyboard, mouse, or memory. And no, they cannot spread to people. How viruses spread and how to avoid themFundamentally, viruses are spread by transferring files between computers. Early viruses were spread on floppy disks, and that is still a common route to a viral infection. Any other method used to share files--like shared network drives, Internet downloads, and e-mail attachments--can also spread viruses. Therefore, the first steps in avoiding virus infections are to learn to recognize what actions increase the risk of infection and to take steps to avoid them:
There are also some settings on your computer that will make it less susceptible to virus infection:
Anti-Virus softwareYou don't need to be concerned about viruses if your computer is completely isolated. Isolated means that the computer is not on the Internet at all, even for e-mail; it's not on any kind of local network; and you don't share files or floppy disks with any other computer or user. If that's not the case, you need to have current anti-virus software installed and running on your computer. The University of Alabama provides anti-virus software for both Windows and Macintosh computers. It is licensed for home and office use. Windows users will notice a change this fall. The software the University had been distributing, Dr. Solomon's Anti-Virus Toolkit, is no longer being marketed, so the University is now using McAfee VirusScan. Macintosh users will continue to use Virex. Either program can be downloaded from the Seebeck Computer Center Software Library, located at computercenter.ua.edu/software. No matter which anti-virus package you are using, you must do two things in order to be protected. First, you need to make sure that your software is scanning all files (not just executables) on both reads and writes. The software distributed by the University comes with this as the default setting. If you obtained anti-virus software through another source, you should consult its help files on how to make sure it does the same. Second, your anti-virus software won't do any good if it is not kept current. New viruses come out all the time, so if your software hasn't been updated in six months, you aren't being fully protected. There are two VirusScan downloads: one for campus computers and one for home computers. The campus computer version is set up to automatically update its virus definitions once a day, but it requires a permanent network connection. The home computer version must be updated manually. Virex users can choose between eUpdate and manually downloading and installing the monthly updates. More information about updating these two programs is available at the Software Library. Virus warningsNo discussion of computer viruses is complete without discussing the virus warnings you get through e-mail. Almost all of those warnings are hoaxes! Messages that include instructions to "forward to everyone you know;" quotes attributed to people at the Federal Communications Commission (FCC), America Online (AOL), or Microsoft; impossible virus symptoms (like sound card damage, see above); or vague dates (yesterday, today, this year, in three months) are almost always untrue. Contrary to many people's initial reaction, it is not better to forward a warning "just in case" it turns out to be true. These letters act like a real virus, using valuable network resources when well-meaning people send them to "everyone they know." Getting innocent bystanders to help flood the Internet with useless messages can be just as effective as writing a program that does the same thing. Also, keep in mind that forwarding a chain letter like this is usually prohibited by your network's terms of service. Most of these virus warning letters can be deleted and ignored. However, if you do receive one that looks convincing, you might want to investigate it further. There are numerous Web pages that provide information on real and fake virus warnings. Two such sites are www.kumite.com and urbanlegends.about.com. Patrick Crispen's Urban Legends Combat Kit (www.netsquirrel.com/combatkit) provides cut-and-paste responses that you can use to reply to the person who sent you the virus warning. Enabling Microsoft Office Macro Virus WarningsOffice 97/98In each Office 97/98 program that can use macros (Word, Excel, and Access):
Office 2000In Word and Excel:
Access 2000 does not have the concept of security levels. You should avoid opening Access databases from unknown sources and make sure to keep your anti-virus software updated. |
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