This challenge was part of the hardware category, and was pretty interesting. Here is the challenge description:

One of our enhanced radio telescopes captured some weird fluctuations from a nearby star. It was idle for decades due to the fact that it was fully enclosed by a Dyson Sphere but its patterns began to change drastically leading us to believe that someone is controlling part of the megastructure to release energy and send these pulses directed to us in order to transmit a message. They must have known that our equipment can read even the slightest fluctuations.

Introduction

A few years ago, I bought a remote controlled outlet from Walmart. I don’t recall the exact price, but it was less than $20. It was pretty much purchased for the explicit reason of trying to understand how they worked. The end goal, is that I wanted to know if

1. I could decode/intercept the signals
2. It was vulnerable to replay attacks

Tools Used

• RTL SDR
• Yardstick One
• Inspectrum
• GQRX
• rfcat

This is going to be quite a long post, so I suggest getting a cup of coffee before continuing. At the end, I have included a youtube video showing the entire process.