Russian hackers allegedly used popular antivirus software to steal NSA secrets

Moscow-based Kaspersky Lab is at the center of the case.

On his home computer, the man was using antivirus software from the Moscow-based company Kaspersky Lab, sources said. Russian-backed hackers were able to target his computer and steal his files through the software, sources added.

The still-unidentified man has been cooperating with federal investigators, according to sources.

Today's news comes a month after the Department of Homeland Security directed all 430 departments, agencies and offices comprising the U.S. government to rid their systems of any software made by Kaspersky Lab, one of the world's most renowned cybersecurity firms. U.S. officials allege the company has ties to the Russian government, and they have increasingly expressed concern that foreign hackers could try to utilize Kaspersky Lab software to spy on Americans, steal sensitive files or attack critical infrastructure.

"This action is based on the information security risks presented by the use of Kaspersky products on federal information systems," DHS said at the time. "The risk that the Russian government, whether acting on its own or in collaboration with Kaspersky, could capitalize on access provided by Kaspersky products to compromise federal information and information systems directly implicates U.S. national security."

As ABC News previously reported, the FBI launched a counterintelligence investigation of Kaspersky Lab several years ago. The agency has recently taken new steps to assess Kaspersky Lab's relationship with Russian intelligence services, including interviewing company employees based in the United States.

Kaspersky Lab CEO Eugene Kaspersky has called U.S. government efforts "extreme."

"Kaspersky Lab is facing one of the most serious challenges to its business yet, given that members of the U.S. government wrongly believe the company or I or both are somehow tied to the Russian government," he recently wrote on his blog. "Basically, it seems that because I'm a self-made entrepreneur who, due to my age and nationality, inevitably was educated during the Soviet era in Russia, they mistakenly conclude my company and I must be bosom buddies with the Russian intelligence agencies ... Yes, it is that absurdly ridiculous."