Looking at the timeline Im guessing they were recruited under cover of Darpa from regular Defcon attendees. L0pht is a good example, Mudge probably was involve

Looking at the timeline Im guessing they were recruited under cover of Darpa from regular Defcon attendees. L0pht is a good example, Mudge probably was involved at one point, he lured a lot of geeks and hackers to the dark side.