The WannaCry ransomware attack is an ongoing worldwide cyberattack by the WannaCry ransomware cryptoworm, which targets computers running the Microsoft Windows operating system by encrypting data and demanding ransom payments in the Bitcoin cryptocurrency.

The attack started on Friday, 12 May 2017, and has been described as unprecedented in scale, infecting more than 230,000 computers in over 150 countries. Parts of Britain's National Health Service (NHS), Spain's Telefónica, FedEx and Deutsche Bahn were hit, along with many other countries and companies worldwide.

WannaCry spreads across local networks and the Internet to systems that have not been updated with recent security updates, to directly infect any exposed systems. To do so it uses the EternalBlue exploit developed by the U.S. National Security Agency (NSA), which was released by The Shadow Brokers two months before. A "critical" patch had been issued by Microsoft on 14 March 2017 to remove the underlying vulnerability for supported systems, nearly two months before the attack, but many organizations had not yet applied it. Those still running exposed older, unsupported operating systems such as Windows XP and Windows Server 2003, were initially at particular risk but the day after the outbreak Microsoft took the unusual step of releasing updates for these operating systems too.

A DEVASTATING new version of the “WannaCry” virus that hit the NHS has been discovered – and it is infecting 3,600 computers an hour, a cyber security firm revealed.