How does antivirus work ?

[mike13]

I always thought that an antivirus program was supposed to
STOP any virus or worm from ENTERING your computer. Over the past two years my friend and I have gotten viruses even though we both keep our antivirus programs up to date. She has no idea where she gets her viruses. I usually get mine from Kazaa.
Both of our antivirus programs had notified us that there was a virus, and we were able to quaranteen it and then delete the file that was infected etc. So I have changed my idea of how the antivirus works. It does not really stop the virus from entering your computer, it just notifies you of the virus so you can take corrective action. Is this correct ??? Thanks, Mike

[Conan]

That's right Mike13. Anti-Virus programs are more of a "reactive" rather than "pro-active" reaction to viruses.

This company claims to be Pro-active but they are not very well known:

http://www.finjan.com/

[mike13]

Thanks Conan for the confirmation. It makes sense now.

[SupaStar]

AntiVirus software can only detect a virus if it has an example of what the virus code looks like. Thats why it's so important to update your virus definitions. It compares code on your PC to examples of viruses that has stored in it's virus definitions. If a match is detected, it then alerts you to the virus' presence and from there you can usually delete the infected file or clean it.

It would seem a bit hard for any antivirus software to be totally pro-active however, since the virus "code" has to reach your machine in order to be compared with the virus definitions.

[Stripe]

I unfortunately do not know how Kazaa transfer files, but if Kazaa works like the eDonkey network, then what happens is that it will download chunks of the files as they come available. Probably what is occuring is that the virus is not "built" yet when it comes to your pc. Well, separately, these chunks do not contain a virus. The virus only becomes the virus when all the "chunks" are pieced together. This is more than likely the reason the virus scan does not pick them up on your pc.