# **Challenge 4: "Invisible Wires"**

You’ve infiltrated a secure facility to extract a prototype device believed to hold critical secrets. After ripping the main board from its casing and making your escape, a sudden realization hits (**you left a secondary board behind**), still wired in and powered. 

Unexpectedly, the stolen board is trying to communicate with its twin over **I2C**, as if expecting a response. It’s time to turn the tables: tap into the bus, reverse the dialogue, and extract what it’s trying to say.

**Your mission is clear:**

1. **Identify the I2C lines** used for board-to-board communication.  
2. **Reverse engineer the protocol** or expected responses from the second board.  
3. **Emulate or spoof the missing board** to trigger a flag or secret message.  

## Setup

![Challenge Setup](docs/04_setup.png)

## Notes

Fire up the logic analyzer and see it's lookign for a device with a specific address:

![logic analyzing](docs/04_logic_01.png) 

So I made a small arduino sketch to emulate this: [04_arduino.ino](docs/04_arduino.ino)

The next time I checked the logic analyzer:

![logic analyzing](docs/04_logic_02.png)

This decodes to:

```
TS{1_N33D_/\/\y_8u66y}
```