picoCTF writeup : buffer overflow 0

Challenge Details

Name : buffer overflow 0

Category : Binary Exploitation

Difficulty : Intermediate

Description

Let's start off simple, can you overflow the correct buffer? The program file and the source file is given here.

First Look

When u launch the instance, you can predict that u have to exploit the input buffer.

Solution

Using simple pwn tool script, this can be achieved. For this challenge, I used this script …

from pwn import *
print(cyclic(600)) # you can tweak the value "600" according to the challenge need.

This script generates 600 bytes which overflows the buffer and gives us the flag.

The final flag : picoCTF{ov3rfl0ws_ar3nt_that_bad_c5ca6248}