April 22, 2004

Protecting computers from viruses
Beyond installing anti-virus software

By Rick Dexter
Special to the Times

The recent rash of new computer viruses have been wreaking havoc with the Internet and costing businesses amazing amounts of money both cleaning and protecting their computers from infection. My company gets calls at least twice a week to troubleshoot an unstable computer where we find both a virus-infected system and a surprised user who thought their computer was protected by virus software.

Computer viruses are software programs that can delete and corrupt files, capture passwords, make computer systems slow and unstable, or allow hackers to take control of a computer through an Internet connection. Most modern viruses propagate themselves via e-mail attachments. There are some viruses that could go unnoticed on a system for months or even years, but which can still be very dangerous.

There are many considerations in a comprehensive anti-virus plan, and one of the most important ones is anti-virus software. Most of these programs are purchased commercially, and a few are available on the Internet for free. The anti-virus software program is loaded on your computer and it watches everything that goes on. If the program spots something it recognizes as a virus, it alerts you and takes actions to keep your system from becoming infected.

All anti-virus programs use a database of virus “signatures” in order to recognize viruses. Some programs may call these “definitions,” “patterns,” “defs,” or “dats,” depending on the software vendor. Most vendors charge an annual subscription fee for online access to signature updates. With most programs this download happens automatically, but a few programs require you to do it manually.

It is extremely important to renew a signature subscription when it expires because most virus infections are caused by new viruses and outdated signatures will not detect them. Almost all of the anti-virus software programs will display the date of their signature file. It is very important to check that date frequently to make sure the updates are still working. Virus signature files should never be more than a week old. New viruses can sneak into a system before signatures are updated, so it is a good idea to have your program check for updates at least daily. Since some viruses can disable anti-virus software, outdated signatures could indicate a possible infection.

I commonly find that people confuse the virus signature subscription service with the software program itself. In general, a subscription only updates the virus signatures, not the software. The software program itself still needs regular updating in order to detect new virus techniques and prevent viruses from disabling the software. An anti-virus software program that is more than two years old should be upgraded to a more recent version. People who write viruses are always finding ways around anti-virus software, and regular software updates will maximize your protection. A good rule of thumb is to never renew a subscription more than once without upgrading the software program also.

Besides installing anti-virus software, another key approach to virus protection is regular system backups. If you're like me and hate to burn backup CDs, next month's column will talk about an effortless backup strategy for home computers and small business networks.

Rick Dexter, founder and CEO of NDYNAMICS Network Professionals in Campbell, lives in Almaden. Rick has over 25 years of experience designing and supporting computer networks, particularly for small businesses and startups seeking reliable and scalable IT infrastructure. If you have a computer question that you would like to have answered in a future column, e-mail it to computerconnection@ndynamics.com .