picoCTF2019 Reverse Engineering Asm

Hello, here's my take on the picoCTF2019 reverse engineering asm challenges. If you don't know assembly, please watch a few tutorials on it: http://opensecuritytraining.info/IntroX86.htmlhttp://opensecuritytraining.info/IntermediateX86.html asm1 - Points: 200 CMP: Compares the first source operand with the second source operand and sets the status flags in the EFLAGS register according to the results. The comparison is … Continue reading picoCTF2019 Reverse Engineering Asm

Bypassing ptrace calls with LD_PRELOAD on Linux

Hello, Here's a quick article on how to bypass calls to ptrace when debugging a Linux executable. By calling ptrace with the PTRACE_TRACEME option, a process can detect if it's being debugged and execute different instructions. This an effective anti-debugging technique. For example, take the following C program: #include <stdio.h> #include <sys/ptrace.h> int main() { … Continue reading Bypassing ptrace calls with LD_PRELOAD on Linux

Root-Me: GB – Basic GameBoy crackme walkthrough

Hello, In this article I will describe how I solved the GB - Basic GameBoy crackme challenge from Root-Me. Before reading this article you should attempt to solve the challenge on your own. Start by reading/skimming through the GameBoy CPU manual then download an emulator such as mGba and play with the ROM. To disassemble the ROM I've used Ghidra and mgbdis. … Continue reading Root-Me: GB – Basic GameBoy crackme walkthrough