The WannaCry ransomware attack was a worldwide cyberattack in May 2017 by the WannaCry ransomware cryptoworm, which targeted computers running the Microsoft Windows operating system by encrypting data and demanding ransom payments in the Bitcoin cryptocurrency.

It propagated by using EternalBlue, an exploit developed by the United States National Security Agency (NSA) for Windows systems. EternalBlue was stolen and leaked by a group called The Shadow Brokers a month prior to the attack.

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