Toddler Writeup

CTF By Jakom

Toddler

In this write-up ,we're going take a look at Toddler reverse engineering challenge . we were given a binary file .

So let's try to execute the program and see what happend :

we're asked to enter a password ,but we get Nop, incorrect password we should find the correct password.

so if try to run it with ltrace

Sometimes if there's a string compare being there we will able to enter a input and we would see what actually being compared, but in this case nothing done here .

let's run strings and see if the expected input sitting there somewhere.

and we see a thnb{%s} here and some other stuffs.

GHIDRA

So let's run ghidra to take a look at the assembly and decompiled code and get better idea what going on.

And we can see that we have boucle and for each character in "s3cure_p4ss" we make a character operation ,we substract 10.

so to be able to get the password and make the flag being displayed , we should create a script do that for us.

Let’s run the program:

Here is the flag.

Written by syntaxx