The Journal found that Hewlett Packard Enterprise Co. was so overrun that the cloud company didn't see the hackers re-enter their clients' networks, even as the company gave customers the all-clear.
Inside the clouds, the hackers, known as APT10 to Western officials and researchers, had access to a vast constellation of clients. The Journal's investigation identified hundreds of firms that had relationships with breached cloud providers, including Rio Tinto, Philips, American Airlines Group Inc., Deutsche Bank AG, Allianz SE and GlaxoSmithKline PLC.
FBI Director Chris Wray called it the hackers' equivalent of stealing the master keys to an entire apartment complex.
https://www.foxbusiness.com/technology/major-us-companies-breached-robbed-and-spied-on-by-chinese-hackers