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Kill worms dead

Posted on 28 Jul 2004 at 17:20

Using anti-virus software is no longer enough to keep your systems clear of malignant programs. Simon Edwards explains how viruses work, how to discover an infection and how to recover from one

You know computer viruses have hit the big time when the public is warned about them on a Monday morning by national television. Thousands of people arriving at work to be greeted by an unusable system is big news, so the computer virus has climbed the news agenda. The media generally puts the frighteners on computer users, but you don't have to be a security guru to minimise your chances of becoming infected. You don't have to be a genius to disinfect your computer either, but there's more to combating viruses than relying on the copy of Norton AntiVirus that came with your PC. We're going to show you how to become a virus killer.

Anti-virus software works reactively, relying largely on updates made available by the vendor. The speed at which these are created and made available directly affects the usefulness of the anti-virus program. When floppies were the main transport medium for viruses, this model of protection was sufficient.

But the Internet, which allows viruses to spread faster than anti-virus companies can react, has reduced the effectiveness of anti-virus software. We need to be more aware of how to protect ourselves, above and beyond relying on £30 software packages.

Viruses have been multiplying exponentially every year since 1995, according to McAfee's research labs. This increase is largely due to the spread of Internet access from universities and forward-thinking companies to nearly every home in the developed world. Email, in particular, has long been the virus writers'friend.

It has been many years since floppy disks posed the greatest threat to your computer. Instead, you're far more likely to receive an email message from a friend, politely offering you an attractive attached file. It seems that many of us are still happy to open these attachments despite relentless advice from the media to be wary.

But it's not just attachments and email we need to beware of: viruses are still making their way to us using tried and tested methods you might think software developers should have closed by now. Today's top virus is the Internet worm, which is back with a vengeance after its first outing in 1988. Combine a virus, a network and software containing security flaws and you get a worm, the first of which was written 16 years ago by Robert T Morris at Cornell University.

If you want to experience one first-hand, you only have to turn off your personal firewall and dial up the Internet using any free ISP to witness the dizzying effects of Blaster or one of its variants within just a few minutes. (Not that we recommend you try this!). Email viruses are very common too, and travel so fast that anti-virus vendors struggle to create the timely updates necessary for anti-virus mail and firewall systems, as well as for desktop programs.

If these threats weren't enough, it's very easy to accidentally download and install insidious spyware programs that in part hijack your computer and are, from a user's perspective, just as evil as a real virus. They often reduce a system's performance to the same degree as a worm.

Know your enemy
With the odds stacked against us like this, it's hardly surprising that even security-savvy, professional PC users occasionally fall victim. In this article, we'll look at how you can protect yourself. We're not going to just recommend you install an anti-virus program and keep it up to date, because that's simply not sufficient to protect your PC.

To make sure you're thoroughly protected, you need to know your enemy, so we'll look at the different ways your PC can become infected with a virus, how you can tell when something is wrong, what you can do to remedy the situation and how to take steps to stop it ever happening again.