The US National Security Agency knew for at least two years about the Heartbleed flaw, and exploited it for cyber attacks according to Bloomberg. The vulnerability affects OpenSSL library and allows an attacker to reveal up to 64kB of memory to a connected client or server. The first suspects are related state-sponsored hackers, of course first thoughts goes to NSA and its TAO cyber unit. The NSA in a tweet denied to have used the flaw in the past. All the website administrators are invited to apply the patch already available for OpenSSL.”]
Source: http://securityaffairs.co/wordpress/23920/intelligence/heartbleed-flaw-nsa.html