The WannaCry ransomware attack in May 2017 infected hundreds of thousands of computers globally using exploits from the NSA. It exploited a Windows vulnerability that many organizations failed to patch. This allowed the ransomware to spread rapidly using a worm. The attack significantly disrupted organizations in over 150 countries and caused billions in damages. A security researcher stopped the spread by registering an unregistered domain used in the malware. Users can protect themselves by updating software, avoiding suspicious links/attachments, using security software and backing up data.