But he said his own motivation was a desire to foster Web security. His conclusion was drawn from a database assembled his group from 7,200 individual hacker profiles over the past five years. He has been working with us to catch the people who are doing this and has provided key details,'' Vranesevich added. Earlier Monday, German authorities said they had received no request from U.S. officials related to Mixter. Der Spiegel magazine had reported over the weekend that he was being sought by German police, the FBI and Russian police.
Zombies refer to computers taken over by hackers to launch coordinated attacks on major Web sites.
Welz said computers on networks at two California universities, a midwestern U.S. college and a Berlin university, and a non-academic site in southern California could have been ''virtually'' hijacked to mount the attacks. But the search has been complicated by the absence of much hard electronic evidence to provide a trail back to the vandals, law enforcement officials and security experts said.