A group of hackers have managed to get inside the White House system and get their hands on US president Barack Obama's schedule, although not classified information, it is still highly prized by foreign intelligence agencies.
The FBI, Secret Service and U.S. intelligence agencies involved in the investigation of the intrusion say that Russian hackers, working for their government, were behind this attack, CNN reports.
Even though the seriousness of the attack was played down at first, CNN now says these hackers got their hands on some sensitive data.
Classified information was not compromised, as it is located on a different, more secure network.
The hackers first hijacked a State Department account, and then used it to send a phishing email which was opened.
Once it was opened, they managed to get inside the system. Having accessed the State Department, they were able to infiltrate the White House computer system, according to the report.
The White House confirmed that there was "an event" last year.
"We have classified systems that are secure. We don't talk about where cyber intrusions originate from," said deputy national security adviser Ben Rhodes.
National Security Council spokesman Mark Stroh didn't confirm the Russian hack, but he did say that "any such activity is something we take very seriously."
"In this case, as we made clear at the time, we took immediate measures to evaluate and mitigate the activity," he said. "As has been our position, we are not going to comment on [this] article's attribution to specific actors."
Both the Russian embassy and the US State Department failed to immediately respond to a request for comment.