PENN PRINTOUT
The University of Pennsylvania's Online Computing Magazine

PENN PRINTOUT October 1992 - Volume 9:2

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Safe and sound: Guarding against computer viruses

By Caroline Ferguso

Is it a virus? The question comes at almost any time--whenever software or hardware doesn't operate exactly as expected. Computer users everywhere are aware of the existence of computer viruses, and most are even aware that antiviral software has been developed to prevent virus infections. At the University, antiviral software has been installed in computing labs and is available free of charge to members of the Penn community. Yet computer viruses continue to infect systems on campus.

Computer users need to adopt a comprehensive strategy to keep their systems virus free. In addition to installing and using antiviral packages properly, they need to modify both how they use their computers and how they think about computing. This strategy applies to all microcomputer users, whether they are using their own computer or someone else's, and whether they are using a Macintosh or an IBM PC/compatible system.


Virus basics

A computer virus is a set of programming instructions that attaches itself to a file, application, or some part of the computer's operating system. Once attached, this set of instructions can affect the operation of applications, the integrity of data, or the general functioning of the computer itself, usually in a negative way. Different viruses do different types of damage. NVIR, a virus which affects the Macintosh system, causes printing failures and operating system crashes. The Michelangelo virus, which panicked IBM PC/compatible users in March 1991, deleted the entire contents of a hard drive.

Computer viruses are most often transferred from computer to computer via infected floppy disks. Infection occurs when a floppy disk that is not "write-protected" is used in a computer that has an infected hard disk. When a disk is not write-protected, the instructions that make up a virus can be added (written) to the disk. In general, disks should be write-protected at all times unless the information on the disk is being edited. A 3.5-inch disk is write-protected when the the movable plastic tab on the back of the disk is in the "up" position, not covering the square hole; a 5.25-inch disk is write-protected when the notch on the side of the disk is covered.


The first line of defense

The first step in a comprehensive antivirus strategy is the use of antiviral software. Whether you have your own computer or use someone else's, make sure that it has antiviral software installed and the system is being checked regularly for viruses.

Also make sure that the antiviral software you are using is current. New viruses appear frequently, and antiviral software must be updated to recognize and intercept them. The Computing Resource Center supports Vi-Spy (current version 10.0) for IBM PC/compatible systems and Disinfectant (current version 2.9) for Macintosh systems. Both products can be obtained free of charge from the Computing Resource Center on Locust Walk (bring a blank unformatted disk) and from several other locations on campus. Information on distribution and current versions can be found on PennInfo, the University's online information service.

Once you have the current version of the antiviral software for your computer system installed, make sure you are using it correctly. Check the documentation included with the product, as well as additional information available on PennInfo or from the Computing Resource Center.


"Disk awareness"

An often neglected aspect of a comprehensive anti-virus strategy is something that could be called "disk awareness." Since floppy disks are the primary means by which viruses are spread from computer to computer, being aware of, and controlling, the disks you use in your computer can significantly reduce the risk of infection. There are several ground rules you should follow:

  • Don't use pirated software. Apart from the fact that you are violating copyright, the set of WordPerfect disks you got from a friend of a friend may have passed through many more hands, and computers, than you realize. Disks that have been passed around have a greater chance of being infected than those that have not.

  • Keep program disks write-protected. When you buy a new software package, write-protect the original disks as soon as you open the box. This prevents your original disks from becoming infected if the computer onto which you install the software is infected. Some companies now require you to "personalize" software by allowing information to be written on the original disks. If this is the case, copy the write-protected originals to blank disks and then use the copies to install the software onto your hard drive. If your license agreement does not permit you to maintain a backup copy of the software, erase the copied disks after you have completed the installation to the hard disk.

  • Write-protect data disks when you are not editing files. Disks do not have to be "write-enabled" if you are just printing or browsing the files; write-enable disks only when you will be editing.

  • Have backup copies of your applications (if your license agreement allows it) and data files. Make creating copies of important files a part of your everyday computing routine. If your computer does become infected, you will have copies of all important materials.

Disk awareness also implies a change in the way you think about computing--you need to think about "defensive computing." Keep track of when and where you use your disks. If a disk does become infected, tracking down the source of the infection is just as important as removing the infection from your disk. Consider all disks a potential source of infection. Check all disks for infection, no matter what their origin.


Know your system

In addition to disk awareness, it's important to be attuned to the "behavior" of your system, especially if you own your own computer or use one in an office or work group. Pay attention to problems and act on them. If you get "insufficient memory" messages for applications that used to work, if your application won't print, or if printing causes your system to lock up, don't ignore it! A virus is the least likely cause, but by investigating you make sure. By being aware of sometimes subtle changes, you may discover that you have a virus before it has a chance to do much damage or to spread.

Disk awareness and familiarity with your computer system, together with the correct use of a current antiviral software package are the keys to keeping your system safe and your data sound.

Sidebar: Free antiviral software

Vi-Spy 10.0 and Disinfectant 2.9, the latest versions of CRC- supported virus protection software for IBM PC/compatibles and Macintoshes respectively, are available at various campus sites. Use the latest version to protect your system against new viruses.

  • CRC, Locust Walk, opposite the Bookstore.: Disinfectant and Vi-Spy. M-F, 9 AM-4:30 PM. Supply a blank floppy diskette. Info: 898-9095.

  • Wharton: Vi-Spy only, 210-11 VH; 202, 203 & 116 SH-DH. Various hours. Copy files yourself to your own diskette. Info: 898-8600.

  • SEAS: Vi-Spy, Moore 108-9; Disinfectant, Moore 266. Various hours. Copy files yourself to your own diskette.

CAROLINE FERGUSON is Front Desk Coordinator for the Computing Resource Center.