A Brief WannaCry Washup.

Now that the Wannacry saga is coming to an end it is important to understand what happened and why.

Firstly it wasn't Windows XP and Server 2000 affected as the spread of the virus would be unreliable. 

Secondly, the virus was not started using email attachments but by the alleged NSA's leaked EternalBlue and DoublePulsar cyber weapons. The majority of the machines infected were running unpatched versions of Windows 7 and Server 2008. Microsoft had released a patch earlier this year (March 2017) had this been applied the attack would have likely failed.

Essentially, vulnerable machines were controlled using a SMBv1 (Server Message Block version 1) exploit via the EternalBlue exploit and the virus installed using DoublePulsar.