Picoctf2021

IA32 Assembly Language As I was working on picoCTF2021 - filtered-shellcode challenge, I realized that I need to write the shellcode in 32 bit assembly rather than in 64 bit. And compiling 32 bit assembly code is different than compiling 64 bit assembly code using gcc. Great reference: https://academic.macewan.ca/boersn/images/quickref-20121215.pdf First, to create an object file, use nasm. nasm -f elf32 -o file.o file.s. This creates an object file file.o Then link the object file with ld. The object file must have global _start. ...

Description AUTHOR: MADSTACKS Description: I am once again asking for you to pwn this binary vuln libc.so.6 Makefile nc mercury.picoctf.net 1774 Hints: PWNTools has a lot of useful features for getting offsets. References https://faraz.faith/2019-10-12-picoctf-2019-heap-challs/ https://gitlab.com/WhatTheFuzz-CTFs/ctfs/-/tree/main/picoCTF/binary-exploitation/heres-a-libc https://ctf101.org/binary-exploitation/relocation-read-only/ https://heartburn.dev/picoctf-2021-binary-exploitation/#here-s-a-libc My Approach In challenges like this one, you are given an executable, a libc library, and a Makefile to work with. And the first thing I do is to find some information about the executable file. ...

Description While being super relevant with my meme references, I wrote a program to see how much you understand heap allocations. nc mercury.picoctf.net 31153 heapedit Makefile libc.so.6 Hints: It may be helpful to read a little bit on GLIBC’s tcache. My Approach Until this point, I had not done any binary exploits that are related to the heap. And this challenge gave me a better understanding of heap allocation/deallocation and how one can try to exploit the glibc heap. ...