For more than five years, American intelligence agencies followed several groups of Chinese hackers who were systematically draining information from defense contractors, energy firms and electronics makers, their targets shifting to fit Beijing’s latest economic priorities.
But last summer, officials lost the trail as some of the hackers changed focus again, burrowing deep into United States government computer systems that contain vast troves of personnel data, according to American officials briefed on a federal investigation into the attack and private security experts.
Undetected for nearly a year, the Chinese intruders executed a sophisticated attack that gave them “administrator privileges” into the computer networks at the Office of Personnel Management, mimicking the credentials of people who run the agency’s systems, two senior administration officials said. The hackers began siphoning out a rush of data after constructing what amounted to an electronic pipeline that led back to China, investigators told Congress last week in classified briefings.
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