Whats the difference between viruses, worms
- Viruses (virii)
are able to replicate themselves in some way and infect files and other
programs on your pc.
Viruses can do serious damage to your pc such as delete files or even
the whole hard drive. There are also a couple that can damage the bios
on your computer, making it very difficult to repair.
Generally speaking a true virus is passed on by sending a file to someone
else either by e-mail or on an infected floppy.
- Worms are a type of virus that is able to self replicate
itself, without any human interaction and normally these take advantage
of exploits in software such as OE, Word etc.
The major difference between a virus and a worm is that a worm can spread
over networks without any human interaction... and the biggest "network" is obviously the internet.
A lot of worms also have their own SMTP engines which allow them to
mail themselves out to everyone in your address book and contact lists
without you even being aware.
- Trojans (comes from the greek trojan horse fable
that we've all no doubt heard of) are usually files that enter our computer
A common way to get a trojan is by the downloading of say an infected
screen saver. We think we are just getting a screen saver, but in the
.exe file there is extra code which allow a "hacker" (in actual
fact the correct term here should be cracker or script kiddie) to access
to data on our pc, or even gain control of it.
I already have an anti-virus program, do I still need
to use a firewall?
Yes. Although AV will help protect
your PC against being infected by virii, it wont prevent external access
to information on your PC.
Do I need to run a separate trojan scanner?
Whilst it cant harm by doing so, As far as I'm
aware, a trojan horse does come under the "virus umbrella" and most A/V packages also scan for trojans.
Most software firewalls also include trojan scanners. I've
used AV for many many years and I've also used a software firewall for
about 5 years that had its own trojan scanner.
During this time, I've found that the AV pulled up the trojan first,
and the trojan scanner that was part of my firewall has never actually "caught" anything.
However, the firewall did often pull up reports of "script kiddies" port scanning to see if you had any trojans resident on my pc.
I already have "Company A" Anti-Virus, should
I also run "Company B" AV too?
Having 2 different anti-virus programs running on your PC in theory
should cause no harm, but this is freqently the cause of conflicts,
and as such is not recommended.
If you already have a decent AV installed that is kept up to date, there
should be no need to install a second one.
The only exception to this I would recommend is running on of the *online*
checkers such as Housecall if you suspect you may be infected.