http://arstechnica.com/security/2016/08/dnc-staffer-got-pop-up-messages-alerting-of-state-sponsored-actors/
Same groups targeted Whitehouse, State when Joint Chiefs and many commercial entities
https://www.crowdstrike.com/blog/bears-midst-intrusion-democratic-national-committee/
It was a typical remote she'll attack initiated from email or web ads.
Seems like these attacks were preventable to say the least.