The Swiss prosecutors have already closed the case due to the failure of the attribution of the cyber attack. The malware was discovered on computers at the Hotel President Wilson, where talks on Irans nuclear work had taken place a month before, following a tip-off from the Swiss intelligence services. The Israeli government is one of the main suspects, but it has always denied accusations of cyber espionage. A Russian-based security firm speculated the use of a spyware having similarities with the ones used by Israeli cyber spies.”]
Source: http://securityaffairs.co/wordpress/53061/intelligence/iran-nuclear-negotiations.html