Critical Flight was the second hardware hacking challenge of the Hack The Box Cyber Apocalypse Capture The Flag competition. Hello world, welcome to Haxez, in this post I’m going to be discussing my experience solving the Critical Flight hardware hacking challenge. All challenges have a description and you can find Critical Flight’s below.
Your team has assigned you to a mission to investigate the production files of Printed Circuit Boards for irregularities. This is in response to the deployment of nonfunctional DIY drones that keep falling out of the sky. The team had used a slightly modified version of an open-source flight controller in order to save time, but it appears that someone had sabotaged the design before production. Can you help identify any suspicious alterations made to the boards?
Opening Critical Flight Files
I have no previous experience with GBR files. Honestly, it took me far too long to find something that would open them. In the end, I found an application called GerberLogix. The application allowed me to open all the files at once and was very simple to use. It does seem dated but it got the job done for the task at hand.
Critical Flight GerberLogix
As you can see from the image below, when opening the files they are combined. It’s like layers in photoshop or gimp and each layer was coloured differently. There wasn’t much else for me to do so I started selecting and unselecting different layers.
Revealing The Flag
After playing with the layers for a bit I eventually found a flag. However, no matter how I structured it, the flag wasn’t accepted. I initially thought that someone had made a mistake and forgot to add the end squiggly bracket but I should have known better. These folks don’t make mistakes.
Pulling Back The Layers
After tinkering with the layers a bit more, I finally noticed the second part of the flag. Of course, they didn’t forget to close the flag. These are hackers we’re talking about, syntax is incredibly important. As you can see below, there were two parts to the flag and we needed to combine them to solve the challenge.
Critical Flight Review
This challenge was great in my opinion, it didn’t require too much tinkering. Once I found an application to open the files it was simple. I did try opening the files with GIMP as I read somwhere that they were brush files. That didn’t work out too well. Anyway, not much more to say about it. Fun challenge.