"It is not clear how such a high-security network could be penetrated. Such classified computer systems are protected by multiple levels of security and are amo

"It is not clear how such a high-security network could be penetrated. Such classified computer systems are protected by multiple levels of security and are among the most “hardened” systems against digital attack." half a page up... "An Obama administration national security official said: “This was a spear phishing attack against an unclassified network.”" Seems pretty clear to me. People are usually the weakest leak in security.