Is AntiVirus Software Really Necessary?

Is anti virus software really necessary? My take on the AV is, it gives one the ability to remove *Only Known* viruses.

So what good it is to have AV installed on a machine which cannot stop *Unknown* viruses?

Lets say a PC gets infected with a virus/worm [known or unknown], don't you think it would be better if we can stop the spreading to other machines by effectively utilizing OS functionality, if its possible to do in the first place, thereby not having to purchase and install AV software.

If you are *for* the AV solution, I would like to know why? If you are *against* AV solution, I would like to know why?

Cheers
FallenZer0

It's true that antivirus works by using definitionfiles, this is not the best method but still if you get an update wihin a couple of hours maybe the virus hasn't got to your computer yet. Some AV's use a smarter method in combination with definitions which is by running a virtual environment such as the Norman sandbox. Then the virus gets to do it's "thing" in the virtual environment and the AV vill recognize that it's using evil code. The AV then can stop the virus from running in the real environment.

I think a good FW is even more important than AV and also a well educated user is very important. Avoiding bad e-mail and links etc will spare you from the most viruses in combination with a FW. I still think it's good to use AV though.

For AV software, you could also read patching strategies, firewall egress filtering, anti-spyware software. All of the above are important and useful but the most important thing is common sense. Users still need to be careful where they browse, what email attachments they click and what software they download onto their PCS. With the constant threat of zero-day exploits, this is even more important.

Most good antivirus software intergrate some heuristic engine to detect possible malicious code, even if it does not match some specific definition. An intelligent technique for this, is the one Reaper mentioned. I also remember it is possible to define the sensitivity threshold in some software, to balance between too much false positives and negatives. Just like you said, FallenZer0, it is not possible in most cases to remove an unknown (possible) virus, since without a full pattern to be used for removal, interfering with the malicious code part, could result in data loss or file corruption -not to mention that this could be a false-positive case.

As for the necessity of antivirus, personally I would rather avoid having it run in the background since real time checking, though powerful, is usually resource intensive. I think the average user could get away just with using a limited user account, setting restrictive permissions for his files and using common sense on the software he executes. A monthly full system scan, just as a precaution, would also be good and sufficient. This for windows environments.

In unix-like environments you wouldn't need to use antivirus at all.

nske has a good point...UNIX operating systems don't need Anti-Virus software. While Anti-Virus software can't get all the viruses out there, they get the totally noticable ones and destroy them. Anti-Virus definitions get stronger and stronger everytime they come out. I highly recommend that you use anti-virus if you are using windows. UNIX or Linux, nah. Macintosh is also recommended especially.

IMHO, AV softwares are a great contribution in the field of the computer industry since they also serve an integral part in realm of secure computing but they are not totally required and necessary.
as users, we are sometimes helpless whenever we are attacked by viruses and other malicious forms of attacks. we are sometimes unaware of the things happening since sometimes they happen either at the machine level or behind the scenes while browsing an internet site. i mean everything is possible nowadays even getting infected just by merely playing a cd on your pc

it is still up to the user if he decides not to live with an AV solution then that is just fine that is if he is up to the task of "manually" checking his own system for such tasks.

now, it is a jungle out there, and if you are left with only your hands to defend yourself, then i would prefer having a shield and a sword first before i get my hands dirty