This spells trouble for business, which must increasingly devote larger funds to IT budgets to prevent clogged inboxes from dragging down productivity.

"Because spammers are hijacking personal computers and stealing bandwidth to send an unlimited number of spam messages at virtually no cost, businesses can face an escalating series of expenses to ensure their emails remain a viable and productive tool," said Daniel Druker, executive vice-president of marketing at Postini.

In terms of other threats, Kevin Isaac, regional director of Symantec, said home users have become a prime target for attackers seeking financial gains.

"Attackers tend to exploit vulnerabilities in desktop applications more often than network infrastructure," he said. Hackers have also become efficient at masking their techniques. "Current threats attempt to escape detection in order to remain on systems long enough to steal information or provide remote access," he said.

Justin Doo, managing director of Trend Micro, Middle East and Africa, listed Botnets and spyware as the top new developments of 2006. These covert programmes are designed to compromise the integrity of private computers. Extortionists are using these techniques, Doo said, to control large numbers of computers in order to threaten gaming and ticketing sites to either pay up or be shut down.

Last year also saw the growth of phishing attacks in the Middle East, according to Patrick Hayati, managing director for security software at McAfee Middle East.

Phishing is when hackers pose as institutions such as banks and send out fake e-mails. The e-mails ask the recipient to provide personal account information, which hackers use to take out funds.

National Bank of Abu Dhabi, for example, said it gets half a dozen phishing scams directed at the bank per year, typically originating from outside the UAE.