SEOUL—A suspected North Korean cyberattack on Turkish banks last month is broader in scope than originally believed, and has expanded to a global data-theft campaign targeting nations including the U.S. and Australia, according to a new cybersecurity analysis.

The hacking campaign, identified as Operation GhostSecret by cyber researcher McAfee LLC, now spans 17 countries and many industries. The attacks highlight how hackers linked to Pyongyang have evolved beyond their traditional focus on military secrets and cyber provocations.

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