On Saturday the New York Times reported that “senior American officials briefed on the investigation” confirmed a hack of the White House’s unclassified network last year. The breach "was far more intrusive and worrisome than has been publicly acknowledged,” officials said, telling the Times that the perpetrators were likely Russians with ties to the government, if not with direct backing from Russia.
The White House’s classified network, on which message traffic from President Obama’s Blackberry is kept, was not breached, but e-mails he sent to the unclassified network from that device (as well as e-mails sent from that network to him) were obtained.
The Times noted that many senior staffers have two computers in their offices: "one operating on a highly secure classified network and another connected to the outside world for unclassified communications.” The most highly secure material shared between "the White House, the State Department, the Pentagon, and intelligence communities" is kept on a system called Joint Worldwide Intelligence Communications System (JWICS), which was not breached. JWICS also gives access to the front-end for XKeyscore, a system that collects, manages, and processes the massive amounts of data collected by the NSA.