Challenge 2: "Echo Chamber"

Following the success of your first infiltration, you've intercepted another device from the same syndicate. This one seems almost identical — same pinout, same behavior — but something’s off. Your usual tools can’t make sense of the UART output. It looks like the engineers behind this one were clever enough to obfuscate communication by using a non-standard baud rate.

The challenge is a test of patience and precision. You'll need to analyze the signal itself to get in.

Your mission is clear:

1. Identify the UART pins using your probing tools.
2. Determine the correct (non-standard) baud rate via signal analysis.
3. Establish a reliable terminal connection and extract the flag from the interface.

Setup

Notes

I started by running logic to capture the transmissions with the logic analyser

Some simple math to determine the baud rate from the pulse width: (or ask chatGPT like I did)

Baud rate calculation

Given: Bit duration = 32 microseconds = 32 × 10⁻⁶ seconds

Formula: Baud rate = 1 / bit duration

Calculation: Baud rate = 1 / (32 × 10⁻⁶)
Baud rate = 31,250 baud

Answer: 31,250 baud

Whip up a quick glitch-o-bolt config: 02_GoB_config.py

This results in:

This could also be checked direcectly in logic:

(Reading source I know the baud rate is supposed to be 31337)