Category: crypto
Author: Rok0'sBasilisk
Hey, Morty! Are you ready for an adventure? *burp*. We gotta jump into the microverse and teach that arrogant Zeep a lesson! This Cathode Ray Thruster is gonna make all their motherboards go faulty ... *burp*
Reveal Spoiler
This is a classic fault injection attack on RSA-CRT signature.
Participants must exploit a race condition by sining a message and at the same time hitting the motherboard with lasers (3rd option in the menu). If timed right, it will result to a different (faulty) signature for the same message which can be used to recover the private key and therefore decrypt the flag.
See solve.py for a working exploit.
EDIT: Or... just send the encrypted flag to be signed, and the script will gladly return the decryption for you since I was lazy enough to not hash the message to be signed xD xD. Thanks to @canopus for pointing this unintended solution. And kudos to everyone that solved the challenge in either way.