Thanks NSA! EternalBlue vulnerability

Tens of thousands of computers have been hit by two major ransomware attacks in recent months — WannaCry, which took down large parts of the NHS, and Petya/NonPetya, a suspected worm that's still wreaking havoc across the globe.

At the centre of these ransomware outbreaks is a Microsoft Windows security vulnerability called EternalBlue. To keep you up to speed on the exploit here's everything i know about it.

What is EternalBlue?

EternalBlue is the name given to a software vulnerability in Microsoft's Windows operating system. The tech giant has called it EternalBlue MS17-010 and issued a security update for the flaw on March 14. The patch was issued before the WannaCry ransomware spread around the world and those who had updated early would have been protected.

The vulnerability works by exploiting the Microsoft Server Message Block 1.0. The SMB is a network file sharing protocol and allows applications on a computer to read and write to files and to request services that are on the same network.

Microsoft says the security update it issued is Critical and following WannaCry it released a rare Windows XP patch after officially ending support for the software in 2014.

Infection is almost always made by email but the latest version of WannaCry spread laterally through the computer networks of infected organisations. The NSA’s Eternal Blue allows the malware to spread through file-sharing protocols set up across the internal networks of organisations, many of which criss-cross the globe.
A highly classified NSA arsenal of digital weapons leaked online last year by a group called the Shadowbrokers as the likely source. They seem to have adapted one particular tool, Eternal Blue, and that would explain why this is spreading so very fast.

This module is a port of the Equation Group ETERNALBLUE exploit, part of the FuzzBunch toolkit released by Shadow Brokers. There is a buffer overflow memmove operation in Srv!SrvOs2FeaToNt. The size is calculated in Srv!SrvOs2FeaListSizeToNt, with mathematical error where a DWORD is subtracted into a WORD. The kernel pool is groomed so that overflow is well laid-out to overwrite an SMBv1 buffer. Actual RIP hijack is later completed in srvnet!SrvNetWskReceiveComplete. This exploit, like the original may not trigger 100% of the time, and should be run continuously until triggered. It seems like the pool will get hot streaks and need a cool down period before the shells rain in again. The module will attempt to use Anonymous login, by default, to authenticate to perform the exploit. If the user supplies credentials in the SMBUser,SMBPass, and SMBDomain options it will use those instead. On some systems, this module may cause system instability and crashes, such as a BSOD or a reboot. This may be more likely with some payloads.

How to protect yourself you ask me? keep your damn pc up to date with the latest patches damnit!