What is WannaCry?

The ransomware uses a vulnerability first revealed to the public as part of a leaked stash of NSA-related documents in order to infect Windows PCs and encrypt their contents, before demanding payments of hundreds of dollars for the key to decrypt files. It comes in two parts.

Part 1

Exploit, whose purposes are infection and propagation.

Part 2

Encryptor, that is downloaded to an infected computer. It encrypts the data and blocks access to a computer or its data and demands money to release it.