Credit: North Korea(?)
Shutting down German train systems and infrastructure was Childs play for WannaCry. Take a legacy bug that has patches available, a leaked (“NSA”) 0day that exploits said bug, and let it loose by a country whose offensive cyber units are tasked with bringing in their own revenue to support themselves and yes, we all do wanna cry.
An Internet work that makes the worms of the late 1990s and early 2000s blush has it all: ransomware, nation state actors, un-patched MS Windows systems, and copy-cat follow on worms Are you not entertained?!?!?