This year will see a surge in viruses and worms targeting handheld devices, mobile phones, wireless networks and embedded computers, including car and satellite communication systems, according to IBM.

A report by Big Blue's Global Security Intelligence Services team warns of a "new and troubling trend" as viruses targeting PDAs and mobiles, such as the Cabir worm, are used by copycats to spur an "epidemic" of viruses aimed at mobile devices.

IBM said that mobile devices are the new frontier for viruses, spam and other potential security threats, and that Bluetooth and other wireless technologies used to connect mobile devices create new avenues of attack for hackers.

It also predicts an increase in the disruption of Voice over IP networks. "In particular, eavesdropping and denial of service attacks carried out remotely against VoIP networks could provide significant damage for enterprise organisations," IBM warned.

Viruses, spam and phishing continued to grow last year, IBM said, while last year also saw the development of new vulnerabilities affecting digital picture formats such as jpeg and bmp images.

"Typically seen as benign files, hackers have discovered ways to embed malicious code in pictures in order to attack a number of different applications used to render images. Clicking on an infected image could set off a virus or worm without the user's knowledge," IBM said.

Stuart McIrvine, director of IBM's security strategy, added: "After a year like 2004, many IT departments feel beaten down from combating viruses like Mydoom and Netsky."