On Friday, May 12, attackers spread a massive ransomware attack worldwide using the EternalBlue exploit to rapidly propagate the malware over corporate LANs and wireless networks. EternalBlue, originally exposed on April 14 as part of the Shadow Brokers dump of NSA hacking tools, leverages a vulnerability (MS17-010) in Microsoft Server Message Block (SMB) on TCP port 445 to discover vulnerable computers on a network and laterally spread malicious payloads of the attacker’s choice. This particular attack also appeared to use an NSA backdoor called DoublePulsar to actually install the ransomware known as WannaCry.