Stopping the nasties - the anti-virus
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Stopping the nasties - the anti-virus

Anti-virus software examines the executable files (programs, macros, DLLs, etc) on your PC to see if any have been infected by a virus or worm. If it locates a virus or worm, it will ...

on 2005-04-18 04:11:29

Anti-virus software examines the executable files (programs, macros, DLLs, etc) on your PC to see if any have been infected by a virus or worm. If it locates a virus or worm, it will tell you what it has found and where it found it - and it will attempt to remove or at least disarm the virus. It can do this by removing the malicious code or by moving the infected file into a quarantine area where it can do no harm. Anti-virus software is an essential part of your defences - but you must never fall into the trap of believing that once AV software is installed, you are automatically safe. You are not. To understand this, you must consider the way in which the majority of AV software works... Central to AV software is a database of virus signatures. A virus signature is a piece of unique code or text within the virus itself. The AV software examines each executable file on your PC looking for any of the virus signatures it has within its database. If it finds one, it knows that the file is infected with that particular virus, and acts accordingly. (This approach is not perfect. Sometimes the AV software can 'recognise' the signature and declare a virus when there isn't one - this is known as a false positive, and can be very annoying. The opposite, where the AV software fails to recognise a virus - known as a false negative - is the more dangerous.) The obvious corollary to this is that if the AV software doesn't have the virus signature within its database, it cannot possibly recognise the virus. This is why it is imperative that you update your AV software's virus signature database at least several times every week, and preferably every day. And even then, if the virus you have just caught is a brand new virus that the AV companies haven't seen before - and for which they obviously don't have a virus signature - then your AV software won't recognise it. Well, to be honest, the last scenario is rare - but it could and does happen. So don't install your AV software and assume you're safe - you still need to practice safe-surfing and common sense use of email and attachments.

  • Do not open any attachments that are are not completely certain to be harmless.
  • And switch your email software to 'text only'. Let's face it, having pretty email is really only vanity - you don't need HTML to read the information in your mail...
With all this in mind, you need to choose and install some AV software. You can find examples of free anti-virus software here. Select the one you want, download and install it. Once again we suggest that you follow the instructions and accept the installation defaults - you can tweak it later. But, what you MUST do is run a complete scan of your whole system as soon as you've got the AV software installed. It may take a while, depending on the speed of your computer and the number of files it has to check. Note that anti-virus software usually includes a component that continuously runs in background. For this reason you should only install one anti-virus product on any one machine - two running at the same time could cause problems. [You must not take these pages as specific advice or recommendations - they merely list some of the options that are available. Please see our Terms and Conditions. If you need specific advice, you should employ a professional consultant.]

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