An 18-year-old hacker with a history of celebrity pranks has admitted to Monday’s hijacking of multiple high-profile Twitter accounts, including President-Elect Barack Obama’s, and the official feed for Fox News.

The hacker, who goes by the handle GMZ, told Threat Level on Tuesday he gained entry to Twitter’s administrative control panel by pointing an automated password-guesser at a popular user’s account. The user turned out to be a member of Twitter’s support staff, who’d chosen the weak password “happiness.” [Wired]