Article: Vista Security FAQ

[Shawn]

Q: If a company has a good firewall installed, won't that protect it
from all these attacks?

A: No. Firewall products are very useful for controlling what comes
into or goes out of a network. But a firewall is like a computer (in
many cases, a firewall is a specialized computer); it does only what
the person who configures it tells it to do...<snippet>

Q: I think I understand the differences between a virus, a Trojan, and
a worm. But what are all these other types of viruses I hear about:
stealth viruses, polymorphic viruses, armored viruses, and cavity
viruses?

A: Stealth viruses are able to conceal the changes they make to files,
boot records, and the like from antivirus programs. They do so by
forging the results of a program's attempt to read the infected files.
A polymorphic virus makes copies of itself to spread, like other
viruses, but the copies are not exactly like the original...<snippet>

Full FAQ here:
http://itmanagement.earthweb.com/entdev/article.php/3677801

Shawn