 Washington (CNN) Russian hackers behind the damaging cyber intrusion of the State Department in recent months used that perch to penetrate sensitive parts of the White House computer system, according to U.S. officials briefed on the investigation. Russian hackers who hit the White House infiltrated an unclassified computer system and apparently accessed details about President Obama's schedule. Ben Rhodes, President Barack Obama's deputy national security adviser, said the White House's use of a separate system for classified information protected sensitive national security-related items from being obtained by hackers. "The fact is that's why we have a classified system because there's less risk in the classified system and that is secure. ADVERTISEMENT 
 
 The breach of Obama’s schedule is notable because the White House maintains tight control over information about the president’s activities.While a general outline of the day’s events is available to the press, Obama takes many meetings and phone calls throughout the day that are not publicly disclosed.The president’s precise whereabouts are also not always known, and the press pool that covers Obama on a daily basis is restricted from accessing many parts of the White House building and grounds.Intimate knowledge of Obama’s activities would be seen as valuable to foreign intelligence agencies like Russia’s.Officials with knowledge of the investigation told CNN that Russian hackers were able to break into the White House system through their foothold within networks at the State Department.The intrusion began when hackers sent what is known as a "phishing" email from a State Department account, infecting a White House computer with malware, the investigators said.The State Department has been battling its own highly sophisticated cyber intrusion for months, though exactly which portions of its network remain breached is unclear.Private security experts had suspected there was a link between the State Department and White House break-ins.Russia is a key adversary of the United States in cyberspace, and is believed to have infiltrated most U.S. critical infrastructure, including installing malware in software that controls everything from oil and gas pipelines to wind turbines to nuclear power plants.The White House breach made headlines last year as a sign of hackers’ increasing access to the highest levels of the U.S. government.White House officials confirmed in October that its unclassified system had been breached. As in many hacks, investigators believe the White House intrusion began with a phishing email that was launched using a State Department email account that the hackers had taken over, according to the U.S. officials.
– Russian hackers' apparent infiltration of the White House computer network in October wasn't exactly confidence-inspiring, even though it was the unclassified portion of the system that was breached. Now US officials say some of the unclassified information that made its way onto hackers' screens was related to President Obama's itineraries—not classified knowledge, but not exactly public knowledge, notes CNN. The Hill points out that although the press has access to "a general outline" of Obama's daily routine, there are still phone calls and meetings that aren't made public, and that foreign spies would apparently love to know about. Obama's exact location at any given point during the day is also often kept on the down-low, and certain parts of the White House are off-limits to the press, the Hill adds. Besides the White House scheduling and press offices, others who use the hacked system include the general counsel's office and the budget and legislative liaison offices, ABC News reports. The hackers are believed to have accessed the White House network by first hacking State Department files, according to investigators, which leads to the fear that hackers have gotten back into the State Department system. One official tells CNN that the hackers have "owned" the network "for months." "There's always vulnerability," Deputy National Security Adviser Ben Rhodes noted at a press conference, per CBS News. "The fact is that's why we have a classified system because there's less risk in the classified system, and that is secure." (The FBI is going after one Russian hacker in particular.)