content: No, we don't know, and given the psy-ops that the U.S. government uses on its own citizens, I don't know if we'll ever really know.  The rush to blame the Russians is somewhat similar to the rush to blame North Korea for the Sony hack.  In both cases there's circumstantial evidence but no smoking gun, and sources can easily be spoofed/obfuscated and someone else's code used in your attack, etc.