A 'kill switch' is slowing the spread of WannaCry ransomware

Friday's unprecedented ransomware attack may have stopped spreading to new machines -- at least briefly -- thanks to a "kill switch" that a security researcher has activated. The ransomware, called Wana Decryptor or WannaCry, has been found infecting machines across the globe. It works by exploiting a Windows vulnerability that the U.S. National Security Agency may have used for spying. The malware encrypts data on a PC and shows users a note demanding $300 in bitcoin to have their data decrypte...