NSA has infected 50,000 computer networks with viruses worldwide

The U.S. National Security Agency has hacked more than 50,000 computer networks worldwide last year, infecting them with viruses that are used to perform sophisticated spying operations, according to a document leaked by Edward Snowden.

The new discovery comes from a PowerPoint 2012 document, published by the Dutch newspaper NRC Handelsblad. The document shows a world map that highlights, among other things, more than 50,000 "plants around the world" under the category "CNE" (Utilizing computer network).

Tailored Access Operations Unit, a team of NSA hackers and CNE branch, has carried out the attack against the Belgian telecom company, Belgacom, according to NRC Handelsblad. However, the attack was reported earlier that was conducted by the NSA's ally, the Government Communications Headquarters in the UK, a British intelligence agency.