N.S.A. Breached North Korean Networks Before Sony Attack – NY Times

A New York Times-based report claims the NSA ran a classified program that compromised networks used by North Korean cyber units (Reconnaissance General Bureau / Bureau 121), deploying malware as an "early warning" to monitor their activity; intelligence from that operation was reportedly critical in the U.S. decision to attribute the Sony Pictures destructive hack to the DPRK, raising questions about evidence and why the intrusion against Sony was not flagged earlier.