EternalBlue is a cyberattack exploit developed by the U.S. National Security Agency (NSA). It was leaked by the Shadow Brokers hacker group on April 14, 2017, one month after Microsoft released patches for the vulnerability. On May 12, 2017, the worldwide WannaCry ransomware used this exploit to attack unpatched computers. On June 27, 2017, the exploit was again used to help carry out the 2017 NotPetya cyberattack on more unpatched computers. EternalBlue was among the several exploits used, in conjunction with the DoublePulsar backdoor implant tool.