Threat actors exploit SharePoint flaws to access internal systems, steal sensitive data, and carry out surveillance, impersonation, and extortion.

Multiple hacking groups—including state actors from China—have targeted a vulnerability in older, on-premises versions of the file-sharing tool after a flawed attempt to patch it.

The US agency responsible for maintaining and designing the nation’s cache of nuclear weapons was among those breached by a hack of Microsoft Corp.’s SharePoint document management software, according to a person with knowledge of the matter.