The House Oversight Committee had jurisdiction over this matter and they issued, after brutal hearings--CIO, Donna Seymour, opted for retirement days before she was to endure another round of grilling by the House committee--, the official report which states
“The long-standing failure of OPM’s leadership to implement basic cyber hygiene, such as maintaining current authorities to operate and employing strong multi-factor authentication, despite years of warnings from the inspector general, represents a failure of culture and leadership, not technology,” and
“The agency’s senior leadership failed to fully comprehend the extent of the compromise, allowing the hackers to remove manuals and other sensitive materials that essentially provided a roadmap to the OPM IT environment and key users for potential compromise,”
The report contains 13 recommendations related to OPM organizational design, mission shifting, procurement practices, technology spend, and a host of matters that are designed to mitigate the disaster.
Jason Chaffetz, the Majority Leader of the committee who called for the resignation of the head of the OPM had this to say
"There are people that need to be held accountable because the first breach was unacceptable. But to not take it seriously, to mislead Congress, to delay the actions that would have prevented further loss really put people in harm's way because it went from roughly affecting 4 million to more than 20 million," he told the Associated Press in a Wednesday interview.
"This was a very extensive investigation, and despite all of the problems, I do have hope that Beth Cobert, who is the new Office of Personnel Management director [will make] some major, major changes….But unfortunately, you've got tens of millions of people whose information is already gone, and there's no putting that genie back in the bottle."
There was widespread recognition that China was behind this attack. Consider Susan Collins's statement
Senator Susan Collins, a Maine Republican, said the hackers were believed to be based in China.
Collins, a member of the Senate intelligence committee, said the breach was “yet another indication of a foreign power probing successfully and focusing on what appears to be data that would identify people with security clearances”.