Isn't it
better to have more protection?
Spyware and
viruses can interfere with your computer's ability to
process information or can modify or destroy data. You may feel that
the more anti-virus and anti-spyware programs you install on your
computer, the safer you will be. It is true that not all programs are
equally effective, and they will not all detect the same malicious
code. However, by installing multiple programs in an attempt to catch
everything, you may introduce problems.
How can
anti-virus or anti-spyware software cause problems?
It is
important to use anti-virus and anti-spyware software (see Understanding
Anti-Virus Software and Recognizing
and
Avoiding Spyware for more information). But too much or the
wrong
kind can affect the performance of your computer and the effectiveness
of the software itself.
Scanning your
computer for viruses and spyware uses some of the
available memory on your computer. If you have multiple programs
trying to scan at the same time, you may limit the amount of resources
left to perform your tasks. Essentially, you have created a denial of
service against yourself (see Understanding
Denial-of-Service Attacks for more information). It is also
possible that in the process of scanning for viruses and spyware,
anti-virus or anti-spyware software may misinterpret the virus
definitions of other programs. Instead of recognizing them as
definitions, the software may interpret the definitions as actual
malicious code. Not only could this result in false positives for the
presence of viruses or spyware, but the anti-virus or anti-spyware
software may actually quarantine or delete the other software.
How can you
avoid these problems?
- Investigate
your options in advance - Research available
anti-virus and anti-spyware software to determine the best choice for
you. Consider the amount of malicious code the software recognizes,
and try to find out how frequently the virus definitions are
updated. Also check for known compatibility issues with other software
you may be running on your computer.
- Limit
the number of programs you install - Many vendors
are now releasing packages that incorporate both anti-virus and
anti-spyware capabilities together. However, if you decide to choose
separate programs, you really only need one anti-virus program and one
anti-spyware program. If you install more, you increase your risk for
problems.
- Install
the software in phases - Install the anti-virus
software first and test it for a few days before installing
anti-spyware software. If problems develop, you have a better chance
at isolating the source and then determining if it is an issue with
the software itself or with compatibility.
- Watch
for problems - If your computer starts processing
requests more slowly, you are seeing error messages when updating your
virus definitions, your software does not seem to be recognizing
malicious code, or other issues develop that cannot be easily
explained, check your anti-virus and anti-spyware software.
Authors: Mindi
McDowell, Matt Lytle
Produced
2006 by US-CERT, a government organization.
