Sophos researchers warn of a new worm named 'SillyFD-AA' that is targeting removable drives.

In both its mode of infection and lack of profit motive, 'SillyFD-AA' harks back to the days when viruses were written for kicks rather than money...

'SillyFD-AA' singles out removable drives including USB memory sticks and floppy disks to create hidden files called 'autorun.inf,' that ensure a copy of the worm runs the next time these devices are plugged into computers running Windows.

And, the worm changes the title of Internet Explorer Windows to announce to the world that the computer has indeed been 'hacked by 1BYTE'.

Senior Technology Consultant at Sophos, Graham Cluley, said that while the worm hasn't been widely distributed yet, they are issuing warnings because of the potential danger presented by it.

He said it would be easy to add to this worm, the ability to transmit through other routes such as e-mail and instant messaging.

Cluley remarked that it is interesting to see hackers using different techniques in their attempt to break into peoples' computers. This type of attack is perhaps understandable as so many businesses these days have e-mail gateway protection in place... which means, they can scan files coming into their company via e-mail attachments, but not files coming in attached to keychains in peoples' pockets.

As a precautionary measure, Sophos has advised users to disable the autorun facility of Windows, so that removable devices such as USB keys and CD ROMs will not automatically launch when attached to PCs. Also, any storage device attached to a computer should be checked for viruses and other malware before use.