Stands for French CyberSecurity Challenge by the ANSSI (National Agency for the Security of Information Systems). Its goal was to select two teams of youngsters to tackle the ECSC, an european CTF. I was a year too old to be eligible but participation was open to anyone.

Writeups (full list here)

I threw on there all the notes I took during the challenges, sorry for the format and less-than-stellar explanations of the challenges.

Most of the writeups are in english but I rewrote some of them in french to help french-speakers who asked for a solution at the end of the CTF.

Some of the cool ones :

XoraaS

Binary exploitation challenge : Overwrite the last byte of RBP with an off-by-one buffer overflow to push a controlled address on RIP

microroptor

Binary exploitation challenge : Defeat PIE and ASLR with a leaked function pointer using ROP and ret2plt

Guess me too

Programming challenge : a “guess the number” with a limited amounts of bits of information where the server had the right to lie once when answering.