You may recall the WannaCry Ransomware attack, which crippled hospitals, banks, and other institutions across the world this past summer. The Trump Administration recently blamed North Korea for these attacks, but it's now being reported by Reuters that Facebook and Microsoft also thwarted other North Korea cyber attacks just this last week.
The report does not go into many details, but it does mention that Facebook and Microsoft "acted last week to disable a number of North Korean cyber actions." This is coming from White House homeland security adviser Tom Bossert, who also says that the United States government is calling on companies to "cooperate in cybersecurity defense."
Microsoft President Brad Smith also recently blamed North Korea for the WannaCry ransomware, while also highlighting the need for a Digital Geneva Convention to make it against international law to target civilians with cyber attacks. Microsoft took the rare step of releasing a security patch for Windows XP and Windows 8 to patch WannaCry exploit, but also criticized governments' stockpiling of software vulnerabilities.