A California hacker has pleaded guilty to disrupting computer systems - including the network of a hospital - through a malware-fueled attack designed to install adware on infected PCs.

Christopher Maxwell, from Vacaville, California, 20, also confessed to disrupting US military systems during the January 2005 attack. As part of a plea bargain agreement, Maxwell agree to pay $252,000 in compensation to Northwest Hospital and Medical Centre in Seattle, the main victim of his attack, and the Department of Defense.

Maxwell, along with two juveniles, launched an botnet-fuelled attack that was blamed for forcing Northwest Hospital to shut down computers in the facility's intensive care unit, as well as disrupting doctors' pagers.

US military computer systems at the headquarters of the 5th Signal Command in Manheim, Germany, and at the Directorate of Information Management in Fort Carson, Colorado, were also hit. The trio made more than $100,000 in advertising commissions through the attack while leaving victims hundreds of thousands of dollars out of pocket.