LOS ANGELES, CA, USA -- A US computer hacker on Monday pleaded guilty to hijacking around 400,000 computers, including military servers, and infecting them with malicious software. In the first such prosecution of its kind, "botmaster" Jeanson Ancheta, 20, admitted infecting the computers with software that caused them to send spam, show ads and launch crippling attacks on Internet sites. In federal court in Los Angeles, Ancheta admitted conspiring to violate both the Computer Fraud Abuse Act and an anti-spam law, to causing damage to US defense computers and to hacking into computers to commit fraud. His plea comes after...