IT contractors have been told to be on the lookout for viruses that target USB devices.

The latest research from Panda Security finds that 25 per cent of new worms created in 2010 are designed specially to spread via storage devices, as this particular method has proven to be highly effective.

Any piece of equipment capable of storing data is susceptible to this new kind of attack, from mobile phones and external hard drives to USB sticks and MP3 players.

Panda Security has found that 48 per cent of small to medium-sized businesses have been infected with some kind of malware in the last year, with 27 per cent of those finding a USB drive to be the source of the infection.

"Not only does [the virus] copy itself to these gadgets, but it also runs automatically when a USB device is connected to a computer, infecting the system practically transparently to the user," said PandaLabs technical director Luis Corrons.

Research from Security firm Tufin found that 76 per cent of hacking experts think badly configured networks are the primary security weakness for most companies.