This year's C3CTF is as hard as usual.
Not to mention plenty of monstrous pwnables that I didn't even touch to the doorway, but this python challenge takes me roughly 1.5 days to solve in total. Time last so long results from finding the unintended bug which turns the exploit procedure both intricate and fascinating.
Me here mainly focus on the unintended solving analysis, if you wanna see the intended one, please visit the author's github.
Mine unintended exploit is at here.
So now, let's get to it!