The Khong Guan Building CTF Badge | SINCON

The Idea

Emil from SINCON and I were wanting to make a badge for a long time. We finally got a chance to brainstorm an idea for their conference's 2023 edition. It was a unanimous call to build a CTF badge.

The Design

For the design, there were two no-brainer choices: one was the conference's maze-like logo and two - a design inspiration derived from a heritage biscuit company building in Singapore for conference artwork.

The building artwork felt versatile for electronic adoption so that became the starting point.

And so the CTF started taking shape. Building seemingly held 6 floors in total. So the CTF concept became an OSINT hunt that unlocks the floors one after another with each correct flag.

Once the CTF concept was clear, putting it in electronic form was the next big challenge. There was a ton of electronics to cram into thelimited space of single-sided PCB.

And with that, the mini-building was ready to host the CTF firmware.

The Village

For the hardware village - we wanted to build an Ironman marathon of hardware. So the village hosted soldering activity with tiny SMD LEDs soldered upside down and the CTF was left to bring out the skills on the software side. So it bought the best of both worlds together and rewarded those who aced it in record time.

The Working

The badge boots up in a default mode where it glows the centre logo and ground floor doors.

The CTF is full of cool ASCII art and challenges ranging from OSINT, Crypto, and Stegano written in a story mode with detective vibes to it.

To play the CTF, don't forget to turn off the battery power and plug in your micro-USB cable. To interface with the badge, you can use the terminal or something as easy as Arduino IDE's serial monitor. Select the right port and boot up the serial monitor. Serial monitor settings are Both NL & CR with 9600 baud.

To initialise the CTF, send three stars *** in the serial monitor. This will put the badge into the CTF mode and it'll print out the first challenge that unlocks the elevator.

Solving this first challenge will allow the elevator to go to any of the 6 floors and solve those challenges in any sequence.

Once all challenges are solved, the badge throws a trophy-winning screen with instructions about how to get your name on the leaderboard.

The badge will remember the flags even if the cable is disconnected. Happy Hacking!