In 2015, Israeli government hackers saw something suspicious in the computers of a Moscow-based cybersecurity firm: hacking tools that could only have come from the National Security Agency. Israel notified the NSA, where alarmed officials immediately began a hunt for the breach, according to individuals familiar with the matter, who said an investigation by the agency revealed that the tools were in the possession of the Russian government. Israelis spies had found the hacking material on the network of Kaspersky Lab, the global antivirus firm, now under a spotlight in the United States because of suspicions its products facilitate Russian espionage. Last month, the Department of Homeland Security instructed federal civilian agencies to identify Kaspersky Lab software on their networks and remove it, on the grounds that “the Russian government, whether acting on its own or in collaboration with Kaspersky, could capitalise on access provided by Kaspersky products to compromise federal information and information systems directly implicates US national security.” The directive followed a decision by the General Services Administration to remove Kaspersky from its list of approved vendors. And lawmakers on Capitol Hill are considering a governmentwide ban. The NSA declined to comment on the Israeli discovery, which was first reported by The New York Times. Kaspersky spokeswoman Sarah Kitsos said that “as a private company, Kaspersky Lab does not have inappropriate ties to any government, including Russia, and the only conclusion seems to be that Kaspersky Lab is caught in the middle of a geopolitical fight.” She said the company “does not possess any knowledge” of Israel’s hack. The firm’s founder, Eugene Kaspersky, said in a blog post last week that his antivirus software is supposed to find malware from all quarters. “We absolutely and aggressively detect and clean malware infections no matter the source,” he wrote, suggesting that the NSA hacking tools could have been picked up as malware by the antivirus programme. In the 2015 case, investigators at the NSA examining how the Russians obtained the material eventually narrowed their search to an employee in the agency’s elite Tailored Access Operations division – hackers that collect intelligence about foreign targets. The employee was using Kaspersky antivirus software on his home computer, according to the individuals familiar with the matter. The employee, whose name has not been made public and who is still under investigation by federal prosecutors, did not intend to pass the material to a foreign adversary. “There wasn’t any malice,” said one individual familiar with the case, who like others interviewed, requested anonymity to discuss an ongoing case. “It’s just that he was trying to complete the mission, and he needed the tools to do it.” Concerns about Kaspersky have also emerged in the cyber security industry, where some officials say that the firm’s software has been used not just to protect its customers’ computers but also as a platform for espionage.