Wow. From Newsweek:
At the Obama headquarters in midsummer, technology experts detected what they initially thought was a computer virus—a case of “phishing,” a form of hacking often employed to steal passwords or credit-card numbers. But by the next day, both the FBI and the Secret Service came to the campaign with an ominous warning: “You have a problem way bigger than what you understand,” an agent told Obama’s team. “You have been compromised, and a serious amount of files have been loaded off your system.” The following day, Obama campaign chief David Plouffe heard from White House chief of staff Josh Bolten, to the same effect: “You have a real problem … and you have to deal with it.” The Feds told Obama’s aides in late August that the McCain campaign’s computer system had been similarly compromised. A top McCain official confirmed to NEWSWEEK that the campaign’s computer system had been hacked and that the FBI had become involved.
Officials at the FBI and the White House told the Obama campaign that they believed a foreign entity or organization sought to gather information on the evolution of both camps’ policy positions—information that might be useful in negotiations with a future administration. The Feds assured the Obama team that it had not been hacked by its political opponents. (Obama technical experts later speculated that the hackers were Russian or Chinese.) A security firm retained by the Obama campaign took steps to secure its computer system and end the intrusion. White House and FBI officials had no comment earlier this week.