"The W32/Hairy-A worm can automatically infect a PC when users plug in USB drives, which carry a file posing as a copy of the eagerly anticipated novel – ‘Harry Potter and the Deathly Hallows’," warns Oxfordshire-based Sophos. "If the users have allowed USB drives to 'auto-run' they will see a file called HarryPotter-TheDeathlyHallows.doc."

With auto-run enabled instead of the required information, the worm simply shows the phrase “Harry Potter is dead”

"Much of the world is waiting with bated breath for the final Harry Potter novel, and the premiere of the new movie is looming too," states Graham Cluley, Sophos’ senior technology consultant. "There is a real danger that muggles will blindly allow their USB flash drives to auto-run and become infected by this worm."

Ultimately an infected machine will have user names changed to those from the book series and update Internet Explorer Web browser settings to point the default page to Amazon.com, specifically to a cash-in book titled ‘Harry Putter and the Chamber of Cheesecakes’ – nothing too devastating, and for some fans a possible improvement to their systems.