Documents Reveal Top NSA Hacking Unit:

The NSA's TAO hacking unit is considered to be the intelligence agency's top secret weapon. It maintains its own covert network, infiltrates computers around the world and even intercepts shipping deliveries to plant back doors in electronics ordered by those it is targeting.
http://www.spiegel.de/international/world/the-nsa-uses-powerful-toolbox-in-effort-to-spy-on-global-networks-a-940969.html