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OTL Solver
#!/usr/bin/env python3
'''
[iv]
954e47bb4976a6aef3bcf67b8dbe30c6
[server random]
439419b5
client random (hex) >> 954e47bb4976a6aef3bcf67b8dbe30c6
Here is your key => 11 38 84 77 55 f8 a0 60 63 f4 bd d0 f8 45 4e 41
key = '11 38 84 77 55 f8 a0 60 63 f4 bd d0 f8 45 4e 41'
'''
import hashlib
import binascii
from Crypto.Cipher import AES
from pwn import *
'''
username = b'admin'
password = b'asdf\n'
server_random = binascii.unhexlify(b'70ef3e33')
server_iv = binascii.unhexlify(b'd003547aa92414e5eaa062f4c3189f88')
client_random = binascii.unhexlify(b'd003547aa92414e5eaa062f4c3189f88')
key = username + password + server_random
md5_key = hashlib.md5(key).digest()
print(md5_key)
session_key = calc_session_key(md5_key, server_iv, client_random)
'''
def calc_session_key(key, iv, data):
# iv = b'\x00' * 16
target = bytearray(iv+data)
for i in range(16):
aes = AES.new(key, AES.MODE_ECB)
x = aes.encrypt(target[i:i+16])
target[i+16] ^= x[0]
'''
for i in range(16):
print('%02x' % target[i+16], end=' ')
'''
return target[16:]
def get_command(session_key, data):
aes = AES.new(session_key, AES.MODE_ECB)
cmd = aes.encrypt(data.ljust(16, b'\x00'))
return binascii.hexlify(cmd)
count = 0
context.log_level = 'error'
TEST_MODE = False
while True:
try:
r = remote('52.79.243.7', 1337)
# r = process('./problem')
except:
print('connection error')
continue
r.recvuntil('[iv]\n')
count += 1
server_iv = r.recv(32)
if server_iv[0:2] != b'00' and not TEST_MODE and False:
if count % 1000 == 0:
print(count)
r.close()
continue
r.recvuntil('[server random]\n')
server_random = r.recv(8)
if TEST_MODE:
r.sendlineafter("username >> ", "guest")
else:
r.sendlineafter("username >> ", "admin".ljust(16, '\x00'))
if TEST_MODE:
username = b'guest'
password = b'guest1234'
else:
username = b'admin'
password = b'adminadmin123123123mkma'
server_random = binascii.unhexlify(server_random)
server_iv = binascii.unhexlify(server_iv)
client_random = binascii.unhexlify(b'0'*32)
key = username + password + server_random
md5_key = hashlib.md5(key).digest()
r.sendlineafter("client random (hex) >> ", b'0'*32)
try:
session_key = calc_session_key(md5_key, server_iv, client_random)
print('session_key', count, binascii.hexlify(session_key))
# print('debug', md5_key, server_random, server_iv, client_random)
except:
print('error', md5_key, server_iv, client_random)
if not TEST_MODE:
print('session key reset')
session_key = b'\x00'*16
r.sendlineafter('command (hex) >> ', get_command(session_key, b'hello'))
try:
r.recv(1)
print('success')
r.sendlineafter('command (hex) >> ', get_command(session_key, b'flag'))
r.interactive()
break
except:
r.close()
continue
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