An 18-year-old arrested by German police has admitted creating the "SASSER" computer worm. The computer programmer was detained in the northern state of Lower Saxony yesterday, but he has since been released. At the moment police have given no more information. The SASSER worm, which struck a week ago, created havoc and is believed to have affected as many as 18 million computers across the globe and forced some businesses to close temporarily. Home computers, government agencies, hospitals, airlines and banks were all affected. Computers were forced into an unstoppable pattern of shutting down and then rebooting. Although annoying, experts say it does no long-term harm. SASSER is the third major internet infection this year following Mydoom and Bagle.