Wannacrypt0r is a new strain of ransomware.
Unlike its predecessors, it does not require logged in credentials or email dissemination. As soon as a computer is powered on the LAN and/or the Internet, it can be infected. No user interaction is required.
Because it does not require user interaction to propagate, it was capable of infecting more than 100000 computers in 24 hours. Some high-end victims include the british National Health Service (NHS) and its hospitals, spanish telecom operator Telefonica, french car manufacturer Renault and german railway operator Deutsche Bahn (DB).