Reuters report that hackers have been spying on the email of the U.S. Treasury Department for months by breaching their installation of Microsoft 365.
The hackers were able to defeat Microsoft’s platform’s authentication controls and appeared to be highly sophisticated.
“This is a nation state,” said a person briefed on the matter. Russia is believed to be behind the attack, which is believed to be connected with a recently disclosed hack on FireEye, a major U.S. cybersecurity company with government and commercial contracts.
A similar tool has also been used to break into other, undisclosed, government agencies.
“This is a much bigger story than one single agency,” said one of the people familiar with the matter. “This is a huge cyber espionage campaign targeting the U.S. government and its interests.”
“The United States government is aware of these reports and we are taking all necessary steps to identify and remedy any possible issues related to this situation,” said National Security Council spokesman John Ullyot.
National Security Council meeting was held at the White House to discuss the breach.
A spokesperson for the Cybersecurity and Infrastructure Security Agency said they have been “working closely with our agency partners regarding recently discovered activity on government networks. CISA is providing technical assistance to affected entities as they work to identify and mitigate any potential compromises.”
Microsoft has declined to respond to a request for comments, reports Reuters.