Russian hackers stole NSA hacking tools using Kaspersky antivirus

Sens. Burr and Warner said the next phase will include public hearings, including an invitation to tech giants to testify; on "Special Report" Catherine Herridge goes in-depth.

Russian government-backed hackers in 2015 stole US secrets on how to penetrate foreign computer networks and protect against cyberattacks after a National Security Agency contractor put highly classified information on his home computer, The Wall Street Journal reported on Thursday, citing unidentified sources. Unnamed sources say an NSA contractor brought the material home with him in 2015 where it was identified by hackers working for the Russian government through the contractor's use of antivirus software made by Russia's Kaspersky Lab. Kaspersky says it has more than 400 million users around the world, and United States security officials have long believed it works with the Russian government.

Experts told the paper the hack was one of the most serious security breaches in years, and that it provided insight into how Russian intelligence exploits commercial software products to spy on the US.

The stolen material reportedly included information on how the NSA penetrates foreign computer networks.

The reported breach took place in 2015 but wasn't discovered until spring of a year ago.

Kaspersky Lab told the Wall Street Journal that it "has not been provided any information or evidence substantiating this alleged incident" and said it "must assume that this is another example of a false accusation". "As a private company, Kaspersky Lab does not have inappropriate ties to any government, including Russian Federation, and the only conclusion seems to be that Kaspersky Lab is caught in the middle of a geopolitical fight".

The revelation comes as multiple U.S. investigations into Russian efforts to affect last year's presidential election have ramped up.

Last month, the Department of Homeland Security ordered every US government agency to stop using a popular anti-virus program made by Kaspersky Lab, a cyber-security firm based in Russian Federation.

Having such information could give the Russian government information on how to protect its own networks, making it more hard for the NSA to conduct its work.

DHS did not immediately return a request for comment.

As ABC News previously reported, the FBI launched a counterintelligence investigation of Kaspersky Lab several years ago.

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