Computer Viruses

-What are computer viruses?
-How can I protect my computers from viruses?
-My virus-protection software reports that my computer is virus free. What procedures can I put in place to protect my system?
-My virus-protection software reports that it has detected a virus, what should I do?
-My anti-virus software has flagged an e-mail attachment, what should I do?
-What’s the best anti-virus software?
-Where can I get reputable virus and hoax information?

What are computer viruses?

Computer viruses are programs that are designed to spread themselves from one file to another with negative and disruptive results. Over 67,000 known virus threats exist today, with over 300 new ones discovered every month. It is important to understand how your system can be exposed to them, and what you can do to protect your computer.

Viruses can spread to your system easily. The two main ways viruses enter your system are through files added to your system via removable media such as floppy disks or Zip disks, and from downloading from the Internet. You can also get a virus through an e-mail attachment, and, in rare cases, through a plain text e-mail message alone.

Typically a computer virus will replicate itself and try to infect as many files and systems as possible. If your system is infected, when you save a file to a disk you will probably infect the disk, and in turn whoever uses that disk will infect their system.

How can I protect my computers from viruses?

Above all, practice safe computing. There are many anti-virus programs that will check your system for known viruses, scan incoming files, and warn you before any infected files are let in. Since new and different viruses are being introduced all the time, anti-virus databases need to be updated often.

If you have a system that is not currently running virus protection software, the first thing you should do is get an-anti virus program and have it scan your hard drive. It will identify any files that have been infected by any virus it recognizes and offer you the option to repair the file if it can. In some cases infected files can be "cleaned" by your virus protection software; in others, the files will have to be discarded.

There is no way to fully guarantee that your computer will never be infected by a virus or a worm, but there are certain steps you can take that greatly lower your chances of becoming infected:

My virus-protection software reports that my computer is virus free. What procedures can I put in place to protect my system?

Back up your files on a regular basis. If a virus destroys your files, at least you can replace them with your back-up copy. You should store your backup copy in a separate location from your work files, one that is preferably not on your computer. If you get infected in the future, you will really appreciate having clean copies of your files.

Be careful whenever you're installing software or downloading files. Most anti-virus software can be set to scan all floppy and ZIP disks inserted in your system and to scan files that are downloaded to your system, including email attachments. It is highly recommended that you set up your software to do this.

Keep your anti-virus software current, and check regularly with your chosen vendor for updates to their product. This can usually be done through the program by clicking Update or at the vendor's web site.

My virus-protection software reports that it has detected a virus, what should I do?

If your installed virus protection software has detected a virus in your system, first try to get the software to "clean" or "disinfect" the files. Ensure that all library staff and volunteers are aware of the virus situation. Do not attempt to do regular work on the infected computer, and keep others from working at it as well (except for doing work to remove the virus and recover from the infection). If "cleaning" or "disinfecting" the files doesn't work, you'll most likely have to delete these files from your system.

Gather ALL floppy and ZIP disks used by the library and scan each and every one through virus software. This includes all masters, all write-protected disks and all back-ups, and any spares or patron disks stored at the library. Users of infected computers should NOT trade floppy or ZIP disks with other users until those disks have been scanned through virus software and deemed uninfected.

In extreme cases, it may be necessary to reformat your hard drive, destroying all of the data on it. Then you'll have to reinstall your software and data, assuming you have the original software disks and clean backups of your files. In this case, it's a good idea to install your virus protection software first on the empty hard drive, so that the integrity of your backup files and original software can be verified.

You might also want to contact all the people that you've recently exchanged data with -- via floppy disks, e-mail attachments, ZIP disks -- and let them know your system's been infected and theirs may be infected as well. You'd want to advise them to check their system for the appropriate virus or symptoms.

My anti-virus software has flagged an e-mail attachment, what should I do?

Delete the e-mail immediately. It is a good idea to play it safe with attachments in general and not open any unless you know what it is, even if it appears to come from a friend or someone you know. Some viruses can replicate themselves and spread through email. Better be safe than sorry and confirm that they really sent it.

What’s the best anti-virus software?

Different people favor different software packages. Some of the more reputable packages are Norton Antivirus software <>, McAffee products <>.

Where can I get reputable virus and hoax information?

McAffee AVERT (Anti-Virus Emergency Response Team) <>

Information adapted from ZDNet Reviews & Solutions (Bruce Stewart,February 12, 2001), McAffee Anti-Virus Tips 2003
Updated 7/09