From Wired’s Threat Level:
According to DefCon staff, Madigan had told someone she wanted to out an undercover federal agent at DefCon. That person in turn warned DefCon about Madigan’s plans. Federal law enforcement agents from FBI, DoD, United States Postal Inspection Service and other agencies regularly attend DefCon to gather intelligence on the latest techniques of hackers. DefCon holds an annual contest called Spot the Fed, in which attendees out people in the audience they think are undercover federal agents. The contest is good-natured, but the feds who get caught are generally ones who don’t mind getting caught.
DefCon staff say that Madigan was asked four times — two times on the phone and two times at the conference — if she wanted to obtain press credentials, but she declined.
DefCon staff lured her to a large hall telling her that the Spot the Fed contest was in session and that she could get a picture of an undercover federal agent at the contest. When she sat down, Jeff Moss, DefCon’s founder, announced that they were changing the game. Instead of Spot the Fed, they were going to play Spot the Undercover Reporter and then announced, “And there’s one in here right now.” Madigan, realizing she’d been had, jumped from her seat and bolted out the door with reporters carrying cameras chasing after her through the parking lot and to her car.
Video of the reporter being outed.