Rating:
# Neo
Oracle Padding Attack, AES with block size = 16.
```python
#!/usr/bin/env python
# -*- coding: utf-8 -*-
from paddingoracle import BadPaddingException, PaddingOracle
from base64 import b64encode, b64decode
from urllib import quote, unquote
from time import sleep
import requests
import socket
class PadBuster(PaddingOracle):
def __init__(self, **kwargs):
super(PadBuster, self).__init__(**kwargs)
self.session = requests.Session()
self.wait = kwargs.get('wait', 2.0)
def oracle(self, data, **kwargs):
somecookie = b64encode(data)
payload = {'matrix-id': somecookie }
print(repr('Data: ' + data))
print(repr('Payload: ' + somecookie))
while True:
try:
response = self.session.post('http://crypto.chal.csaw.io:8001', data = payload, stream=False, timeout=5, verify=False)
break
except (socket.error, requests.exceptions.RequestException):
logging.exception('Retrying request in %.2f seconds...', self.wait)
sleep(self.wait)
continue
self.history.append(response)
if response.text.find("Caught exception during AES decryption...") == -1:
logging.debug('No padding exception raised on %r', somecookie)
return
raise BadPaddingException
if __name__ == '__main__':
import logging
import sys
if not sys.argv[1:]:
print 'Usage: %s <somecookie value>' % (sys.argv[0], )
sys.exit(1)
logging.basicConfig(level=logging.INFO)
encrypted_cookie = b64decode(unquote(sys.argv[1]))
padbuster = PadBuster()
cookie = padbuster.decrypt(encrypted_cookie, block_size=16)
print('Decrypted somecookie: %s => %r' % (sys.argv[1], cookie))
```
Solution:
```
Decrypted somecookie: Wre7CkPi+rFZpTzV+TAtIHzHNtILVrx2XRdynvWoQVrK88FWdeMvn8QmM2RzWzuNbaIwf9m6RfMhwZKmzIqbQ+zMdSFLZ41Y4Db+q3JZOg0= =>
bytearray(b'flag{what_if_i_told_you_you_solved_the_challenge}\x0f\x0f\x0f\x0f\x0f\x0f\x0f\x0f\x0f\x0f\x0f\x0f\x0f\x0f\x0f')
```
References:
[https://github.com/mwielgoszewski/python-paddingoracle](https://github.com/mwielgoszewski/python-paddingoracle)
