Drives such as USB sticks infected with the virus trick users into installing the worm, according to researchers.
The "Autoplay" function in Vista and early versions of Windows 7 automatically searches for programs on removable drives.
However, the virus hijacks this process, masquerading as a folder to be opened. When clicked, the worm installs itself.
It then attempts to contact one of a number of web servers, from which it could download another program that could take control of the infected computer.
