According to market watcher IDC, the devastating impact of these virus attacks is fuelling security spending, a trend that will continue over the next five years, by when it will be a $4.4bn market.

'The recent onslaught of viruses and worms such as Blaster, Nachi, and Sobig highlight the need for antivirus products and, more importantly, the need to update services,' said Brian Burke, research manager for IDC's security products service in a statement.

Burke added that while corporate customers have long realised that antivirus software is only as good as its last update, consumers and small business customers were only now realising the necessity of subscription-based updates.

IDC added that the global antivirus software market proved to be a primary area for security spending in 2002, achieving $2.2bn in revenues, 31 per up on 2001.

Both corporate and consumer spending on antivirus software increased in 2002, according to the research firm, with consumer spending actually surpassing corporate spending by 8.5 per cent.

'Consumers and small businesses are finally recognising the fact that antivirus software is more of a service than a product,' said Chris Christiansen, vice president for IDC's security products service in a statement.

'Furthermore, the rapid infection by these new worm and virus attacks means that slow responses will cripple most customer environments because they will not be able to get ahead of the initial infection and the far more serious re-infections.'

The analyst also warned that just as virus and worm detection technologies become more sophisticated, so do the virus writers.

IDC said that worms and viruses were increasingly Spam techniques - not just exploiting unprotected mail relays to maximize spread, but also using social engineering to trick victims into opening malicious files.

To combat virus and worm attacks many organisations are adopting a 'layered security' approach that combines solutions such as desktop antivirus, server and gateway antivirus, content filtering, and proactive techniques such as behaviour analysis and heuristics, IDC observed.