IT directors are being forced to spend more of their IT budgets on security as a result of the recent virus plague spearheaded by Blaster and SoBig.

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 to create a market worth $4.4bn.

"The recent onslaught of viruses and worms such as Blaster, Nachi, and SoBig highlights the need for antivirus products and, more importantly, the need to update services," said Brian Burke, research manager at IDC's security products service.

IDC added that consumers are looking for subscription-based services, having learned from the corporate experience that antivirus software is only as good as its last update.

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

"Furthermore, the rapid infection by these new 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 reinfections."

IDC also warned that virus writers are becoming just as sophisticated as the virus and worm detection technologies deployed to thwart them.

The analyst pointed out that virus writers are increasingly adopting spamming techniques, not just in the exploitation of unprotected mail relays to spread more widely and rapidly, but in the use of social engineering to trick victims into opening malicious files.

IDC also warned that new attacks could actually derive revenue from the illegal proliferation of an unauthorised spam server.

It said that to combat virus and worm attacks many organisations are adopting a "layered security" approach which combines a number of solutions.

These include desktop antivirus, server and gateway antivirus and content filtering, as well as proactive techniques such as behaviour analysis and heuristics.