NSA Tool called DOUBLEPULSAR that is designed to provide covert, backdoor access to a Windows system, have been immediately received by Attackers. Malware developed by National Security Agency (NSA) exploiting Windows based Server Message Block (SMBv1) The tool has released by Shadow Brokers hackers Group in April 2017 and it has been used for Wannacry Cyber Attack. The vulnerability existed with windows os which leads to perform Remote Code Execution which was particularly targeted Windows 7 and XP.”]
Source: https://gbhackers.com/windows-eternalblue-doublepulsar/