Shellcon FeatherDuster Workshop Exercise Materials

exercise_server.py

from Crypto.Cipher import AES
import sys

FLAG = '7368336c6c63306e72756c7a'.decode('hex')

def pkcs7_pad(text):
   pad_num = 16 - (len(text) % 16)
   return text + chr(pad_num) * pad_num

cipher = AES.new('yellow submarINE', AES.MODE_ECB)

sys.stdout.write('input? ')
sys.stdout.flush()
print cipher.encrypt(pkcs7_pad(raw_input('') + FLAG)).encode('hex')

host_exercise_server.sh

socat TCP4-LISTEN:9001,fork,bind=127.0.0.1 EXEC:python\ exercise_server.py

solve_exercise_server.py

# Generated by FeatherDuster
import cryptanalib as ca
import socket

def simple_conn(host,port):
   sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
   sock.connect((host, int(port)))
   return sock


def encryption_oracle(text):
   # TODO: Write a function to interact with the ECB encryption oracle
   s = simple_conn('127.0.0.1',9001)
   junk = s.recv(1024)
   s.send(text+'\n')
   response = s.recv(1024).strip()
   return response.decode("hex")

ca.ecb_cpa_decrypt(encryption_oracle=encryption_oracle, block_size=16, verbose=True, hollywood=True)

tcp_client_example.py

import socket

def simple_conn(host,port):
   sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
   sock.connect((host, int(port)))
   return sock

s = simple_conn('127.0.0.1',9001)
print(s.recv(1024))
s.send(raw_input()+'\n')
print(s.recv(1024))