Qatar 2022 matches betting in the blockchain

I imagine that by 2022 cryptocurrency and blockchain will be used by many in Qatar, and in 2022 Qatar will be hosting the world cup. So I had this idea of implementing a football match betting in the blockchain. I decided to write a contract in Solidity for Ethereum to…

NuitDuhack - Matriochka+Invest

We finish rank 8 in Nuit du hack, and we qualified for the finals in Paris - Disneyland ^^/. Here are some quick writeups. Matriochka 1,2,3,4 This was a series of reverse engineering challenges, each binary if solved gives the next one in base64. stage 1 Password in…

unexploitable hackerdom

A friend of mine sent me a challenge called unexploitable download from here (elf64) here it has the following source code : #include <stdio.h> void main() { // no brute forcing sleep(3); // exploit me int buf[4]; read(0, buf, 1295); } compiled with CANARY : disabled FORTIFY : disabled NX : ENABLED…

BKP2016 Unholy and Ashmont writeup

unholy It was a reverse challenge two files are given main.rb and unholy.so #!/usr/bin/env ruby require_relative 'unholy' include UnHoly python_hi puts ruby_hi puts "Programming Skills: PRIMARILY RUBY AND PYTHON BUT I CAN USE ANY TYPE OF GEM TO CONTROL ANY TYPE OF…

A keygen challenge (z3+brute)

On one of the previous CTFs that I played a keygen me binary is given, you can download it from here. We'll solve it in two ways, the easy way which is bruteforce, and the longer way which is using z3. Let us start to understand what the binary does.…