by Renee Dudley

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Last month, Microsoft announced that Chinese state-sponsored hackers had exploited vulnerabilities in SharePoint, the company’s widely used collaboration software, to access the computer systems of hundreds of companies and government agencies, including the National Nuclear Security Administration and the Department of Homeland Security.

The company did not include in its announcement, however, that support for SharePoint is handled by a China-based engineering team that has been responsible for maintaining the software for years.

ProPublica viewed screenshots of Microsoft’s internal work-tracking system that showed China-based employees recently fixing bugs for SharePoint “OnPrem,” the version of the software involved in last month’s attacks. The term, short for “on premises,” refers to software installed and run on customers’ own computers and servers.

Microsoft said the China-based team “is supervised by a US-based engineer and subject to all security requirements and manager code review. Work is already underway to........

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