Rating: 5.0

Oh no! Cthulhu's laptop was hit by ransomware and an important document was encrypted! But you have obtained the encryption script and it seems like the encryption is vulnerable...
Even tough you don't know the encryption password, can you still help recover the important ODT file?

Challenge: https://github.com/docileninja/docileninja.github.io/raw/master/files/cryptolocker.zip
Solution: https://github.com/docileninja/docileninja.github.io/blob/master/files/crack.py

Original writeup (http://van.prooyen.com/cryptography/2016/10/20/cryptolocker-Writeup.html).