Author: LT 'syreal' Jones Location: https://play.picoctf.org/events/72/challenges/challenge/385 Tags: Reverse Engineering, Analog
Can you crack this black box? We grabbed this design doc from enemy servers: Download. We know that the rotation of the red axle is input and the rotation of the blue axle is output. The following input gives the flag as output: Download.
This challenge came with a .zip archive called input.txt (download it here) and a text file called Virtual-Machine-0.zip (download it here). This challenge also came with a hint stating: "Rotating the axle that number of times is obviously not feasible. Can you model the mathematical relationship between red and blue?"
I downloaded the .zip archive and text file, and then proceeded to extract the .zip archive. It contained a file called Virtual-Machine-0.dae, and I tried to identify what kind of file format it is. I worked out that it is an Adobe COLLADA format [1] used mainly for 3D designs.
I tried to find a .dae file reader for the Windows VM and decided to go with FreeCAD [2].