Hackers working for the Russian government reportedly found sensitive information on the home computer of an NSA contractor who was using Kaspersky antivirus software, according to a report.

The Russian government stole information about National Security Agency surveillance and cyberdefense programs, after apparently hacking a contractor with the help of Kaspersky antivirus software, the Wall Street Journal reports.

Hackers working for the Kremlin specifically stole information revealing how the NSA penetrates foreign computer networks and the computer code it uses to do so, the Journal reports. They also reportedly stole information on how the NSA defends networks inside the US.

The reported breach occurred in 2015, when an NSA contractor transferred highly classified material to his home computer, on which he was using Kaspersky software. The incident was discovered the spring of 2016, the Journal says.

Last month, the US government banned all federal agencies from using Kaspersky software over concerns with the Russian-based company's ties to the Kremlin.

In a statement, Kaspersky Lab told the Journal in a statement that it "has not been provided any information or evidence substantiating this alleged incident, and as a result, we must assume that this is another example of a false accusation." The company added that it "does not have inappropriate ties to any government, including Russia, and the company has never helped, nor will help, any government in the world with its cyberespionage efforts."