Le Hack 2023 Challenges

For this new edition of Le Hack, Quarkslab and its experts are delighted to offer you challenges to solve over the two days of Le Hack conference. We wish you good luck and look forward to seeing you on our booth on Saturday, July 1 at 4pm for the prize-giving ceremony.


  • each test is marked out of 20 points
  • identical scores are broken down according to speed of resolution

Circuit Scrambling

You have to reverse the PCB without the chips to get the schematics of the board. See : x
  • U1 is a 74HC32 chip
  • U2 is a 74HC32 chip
  • U4 is a 74HC86 chip
  • U5 is a 74HC04 chip

Once you reversed the schematics, you can deduce the position each switch should have to get all outputs high. Come to the booth, we will use a populated PCB on which you can check if you found the flag. All switches are firstly reset to position zero. It will cost points to set a single switch to position one. So, try to find a solution with a low Hamming weight ;) You can reset and try multiple times, but penalties will add up.

The Bomb

The bomb looks pretty much like some schematics from the Dark Website "Anarchism for dummies":
  • white = adjust bomb timer
  • grey = activate bomb timer
  • purple = deactivate bomb
  • brown = check bomb status
  • yellow = (re)activation button

There is even some example firmware available for an ATmega328P: x and its leaked source: x. Apparently there is still a way to deactivate the bomb by changing some wiring, but we couldn't figure how.


Should we really explain what to do when a bomb is about to explode?


Of course it's forbidden to open the box ;) Usage:
  • If it's flashing red, it's waiting for the initial wiring which is P0-P5, P1-P6, P2-P7, P3-P8, P4-P9.
  • Press the button once you're ready.
  • Initial timer should be set to 3:00. If not, ask us to adjust it before playing.
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