The WCry or WanaCrypt0r ransomware, which rapidly spread across Europe and Asia in May 2017, affected nearly 100 countries and disrupted numerous services, including 45 hospitals in the UK. The ransomware utilized the ETERNALBLUE vulnerability to propagate and execute its damaging activities, such as encrypting files on infected systems. It demanded ransom payments in Bitcoin for file decryption, though it was not guaranteed that paying would ensure data recovery. A notable feature was a "killswitch" function that, when activated, halted the malware's operation, significantly slowing its spread. This was discovered and utilized by researchers, notably MalwareTech, who set up a sinkhole that mitigated the outbreak's impact. The malware's execution involved several technical steps, including exploiting vulnerabilities, setting up encryption keys, and creating persistence mechanisms, with the primary goal of extorting victims for financial gain. Security experts emphasized the importance of patching systems and maintaining backups to prevent such attacks.