Friday, August 15, 2014

Defcon 22 CTF - Badger

Teams were given special CTF badges during the middle of the first day of the CTF:

The badges communicate through an RF link and can send messages to each other. The messages consist in a text (limited to 113 then 200 characters) and an image.

Two serial ports over USB are available, the upper one which is undocumented, and the lower one to load the program.

The main components on the badge are:
  • FPGA: Xilinx Spartan 6 XC6SLX9
  • RF IC: likely a Semtech SX1272 @868MHz, (inscriptions read 1272 1342 W2H617 00)
  • Flash: 4 Mbits ST 25PE40
  • SRAM: 1(?) Mbits Microchip 23LCV
  • Serial: 2x RS232 over USB Prolific PL2303
  • A color LCD screen

Inspecting the badge

When connecting to the upper serial port, we are greeted with:
Application Core v1.0
openMSP430 core by Oliver Girard
p.s. I modded the core to make data executable -sirgoon