PicoCTF 2021 Writeups

our team's writeups for the 2021 PicoCTF competition

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Overview

Points: 50 Category: Reverse Engineering

Description

There is something on my shop network running at mercury.picoctf.net:53740, but I can't tell what it is. Can you?

Hints

  1. What language does a CNC machine use?

Approach

Connecting to mercury.picoctf.net:53740 (through web) results in instructions.gcode

A quick Google search says a CNC machine uses GCode which can have a file extension of .gcode so I pasted that section of code into a text editor and saved it as a .gcode file. NC Viewer can view GCode files:

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Flag

picoCTF{num3r1cal_c0ntr0l_775375c7}