Intel agencies say massive cyberattack on US government was 'likely Russian in origin'

U.S. intelligence agencies on Tuesday attributed the recent massive SolarWinds cyber breach to Russia, saying it was likely an intelligence gathering effort against several U.S. government agencies.

"This work indicates that an Advanced Persistent Threat (APT) actor, likely Russian in origin, is responsible for most or all of the recently discovered, ongoing cyber compromises of both government and non-governmental networks," the FBI, Cybersecurity and Infrastructure Security Administration, and Office of Director of National Intelligence said in a joint statement. "At this time, we believe this was, and continues to be, an intelligence gathering effort. We are taking all necessary steps to understand the full scope of this campaign and respond accordingly."

The intrusion involves software from SolarWinds, which makes IT management tools, that had been adulterated, or "Trojanized," with a vulnerability that could be exploited by hackers to steal information, manipulate systems or plant trap doors and other exploits for future use.

The statement said that under 10 government agencies have been impacted. ABC News has reported five that were breached: the State Department, Energy Department, Department of Homeland Security, Treasury Department and Commerce Department.

"We have so far identified fewer than ten U.S. government agencies that fall into this category, and are working to identify and notify the nongovernment entities who also may be impacted," the statement added.

The agencies also say this is a "serious compromise that will require a sustained and dedicated effort to remediate."

The statement contradicted what President Donald Trump tweeted about the cyberattack in December. He baselessly accused China and brought up the general election being compromised despite no evidence to support it.

"The Cyber Hack is far greater in the Fake News Media than in actuality. I have been fully briefed and everything is well under control. Russia, Russia, Russia is the priority chant when anything happens because Lamestream is, for mostly financial reasons, petrified of discussing the possibility that it may be China (it may!). There could also have been a hit on our ridiculous voting machines during the election, which is now obvious that I won big, making it an even more corrupted embarrassment for the USA," he said.

Secretary of State Mike Pompeo and former Attorney General William Barr attributed the hack to Russia last month.

"It appears to be the Russians," Barr said at a press conference, adding that he couldn't comment any further.

ABC News' Conor Finnegan contributed to this report.