A ransomware cyber-attack that may have originated from the theft of “cyber weapons” linked to the US government has hobbled hospitals in England and spread to countries across the world. "Ransomware is a type of malware that encrypts a user’s data, then demands payment in exchange for unlocking the data. This attack was caused by a bug called “WanaCrypt0r 2.0” or WannaCry, that exploits a vulnerability in Windows. Microsoft released a patch (a software update that fixes the problem) for the flaw in March, but computers that have not installed the security update remain vulnerable."