Protecting your computer from viruses

What is a computer virus and how do I get one?
If you depend on the information stored on your personal computer, you need to understand how computer viruses spread, and you should use anti-virus software to reduce the chance that a computer virus will infect your programs and files.

A computer virus is a program that makes copies of itself and infects diskettes or files. Computer viruses can spread to other computers and files whenever infected diskettes or files are exchanged. Often infected files come as email attachments, even from people you know. The email senders have no idea that they are passing on a file with a virus in it.

Some computer viruses can erase or change the information stored on your computer, other viruses may do little or no harm to your system. Writing and releasing any virus is prohibited by university policy, and anyone who does so will be held legally accountable for damages.

Types of computer viruses
There are currently four types of computer viruses, each spread in a different way.

These viruses are spread by sharing document files from MS-Word (version 6.0 and above) or MS-Excel (version 5.0 and above). Macro viruses are a frequent cause of virus infections, and they can infect both PCs and Macintosh computers. After your computer is infected with a macro virus, any Word or Excel document you create or open may also contain the virus.

“Boot Sector”
These viruses are spread by sharing diskettes between different computers. Any diskette can spread a boot sector virus –even if it is not a bootable system diskette. If you share files by sharing diskettes, you can spread a boot sector virus to other computers, which then can infect other diskettes.

These viruses are spread by sharing program files. Because most users share programs less frequently than they share data or document files, this type of virus is less common than others. A program virus can infect other programs and damage data files on your computer.

“Email” or “Hoax”
These viruses are not really virus programs at all. They are email messages sent by well-meaning people to warn others about a new virus they read of. These false warning messages usually say “be sure to send this to everyone you know” and warn of major damage to your computer or files. Hoax virus warnings can cause huge amounts of Internet traffic and unnecessary worry to others. Please check with someone knowledgeable about computer viruses before you forward such a message.

A virus can not appear on your computer all by iself. You have to get it by sharing infected files or diskettes, or by downloading infected files from the Internet.

A write-protected diskette can not become infected with a virus.

You can not get a virus by reading the body of a Pine email message, although one could be carried in an attachment (e.g., a Word or Excel file). These attachments should be scanned before you read them.

How do I protect my computer?
There are several things that you should do to protect your computer from virus infections:

Use a high-quality anti-virus program, and be sure to update it regularly. Use it to scan any files, programs, software, or diskettes (even new software from a commercial company) before you use them on your computer.

Make back-up copies of important documents or files and store them on separate diskettes. Making backups will also protect your information against accidental file deletion, diskette failure, and other damage.

Whenever you use a computer in a campus lab, be sure to reboot or run “cleanup” before you start your session and log out when you end your session.

Do not share commerical software with anyone. It is a violation of the author’s copyright to distribute such material, and it is a way to spread viruses.

When you get public domain (PD) software for which the author has granted permission to make copies, get it from a reliable source. (For example, and individual you do not know is not a reliable source.) Before you run PD material, use an anit-virus program to inspect for known viruses.

Always scan your diskettes and files after using them on another computer.

Always scan all files you download from the Internet.

Always scan Word or Excel file email attachments before you read them.

How do I get anti-virus software?
You should install the latest versions of anti-virus software on your desktop computer to protect it from viruses. McAfee’s VirusScan is recommended for the Windows environment and Virex for the Macintosh. Both of these products are included in the UW Internet Connectivity Kit (UWICK), a cd-rom available at the University Book Store and its campus branches.

You also can download anti-virus software directly from the Web. The Software Guide provides descriptions and downloading instructions for both VirusScan and Virex.

How should I configure my anti-virus software?
We have a web page detailing how to configure McAfee VirusScan for optimal performance and protection .

What if my computer gets a virus?
Not all damage to your programs and files is caused by viruses: worn out floppies, failing hard drives, user error, and poorly written programs can all cause you to lose data. If your computer is behaving strangely, or if you think your computer has a virus, use an anti-virus program to find out.

If your computer is infected with a virus, DON’T PANIC! Use an anti-virus program to remove the virus yourself, or turn your computer off and find someone who knows how to remove the virus.

If a virus is active in memory, it may prevent anti-virus programs from working correctly. To be sure no virus is active, turn off your computer and reboot from a known-clean system diskette before you begin the disinfection process.

Eliminate all copies of the virus as quickly as possible. Check all your diskettes, and warn anyone else who may have infected files or disks.

Remember, most viruses can be removed without permanent damage to your system, and most virus infections can be prevented. With proper care, your computer can remain virus-free.

Are there UW Newsgroups or Distribution Lists that discuss viruses?
Yes, the local newsgroup, uwash.comp.virus and email distribution list COMP-VIRUS provide the same information about computer viruses and other malicious software that may be of interest to the UW community. Choose the source easiest for you to read.

Either click on the newsgroup link or subscribe to the distribution list by sending email to and including in the body of the letter “subscribe COMP-VIRUS”

Where can I learn more about viruses?
F-Secure (Data Fellows) Computer Virus Info Center
McAfee’s Virus Information Library
McAfee’s Virus Glossary of Terms
Anti-Virus Emergency Response Team (AVERT) – Tools and utilities including those to remover viruses from MS Office Files
AntiVirus Research Center
A short history of computer viruses and attacks, June 2002 Washington Post
Microsoft: 7 Steps to Help Protect Personal Computing Security

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