Hackers made headlines this year when the international protest group Anonymous shut down government and corporate websites, and U.S. and European police moved in. But likely more significant than the antics of so-called “hacktivists” is rising interest by corporations, government security officials and Internet companies in hiring “good” hackers, who can counter attacks by “bad” hackers — cybercriminals. Thefts of money and information via hacked computers are on the rise worldwide, with hundreds of billions in losses annually. The challenge lies in overhauling legal and economic structures to encourage innovative, positive hacks and strengthen defenses against destructive ones, experts say. The Obama administration is proposing a sweeping cybersecurity plan that would require utilities, banks and other economic linchpins to strengthen their systems against computer sabotage. Opponents of the plan argue, however, that new cyberthreats arise too quickly for top-down government regulation to stop them.