Flash CTF – Such a G

By Sandline

Challenge Overview

In this challenge, your objective is to identify and inspect a G-code 3d-printing file to reveal the flag.

Objective

Identify the file as a G-code file and vizualize the 3d tool path with existing software or custom code to reveal the flag letters.

Tools Required

An existing G-code viewer like “Prusa G-code Viewer” or a custom script to visualize the 3d path is required.

Steps to Solve

1. Identify the file as a binary G-code file. Although it does not have a .bgcode extension, the GCDE magic bytes at the beginning of the file reveal its format.
2. Locate software (such as Prusa G-code Viewer) that can open the file, or write a script to parse the file (Image 1)
3. View the 3d tool path layer by layer: note the flag letters embedded in the 3d object (Image 2)
4. Navigate through the layers to reveal the flag.

Flag: MetaCTF{sl1c3d_and_d1c3d}