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             AUSCERT External Security Bulletin Redistribution

        Cisco IP Phones Web Server Remote Code Execution and Denial
                         of Service Vulnerability
                               17 April 2020


        AusCERT Security Bulletin Summary

Product:           IP Phone 78xx Desktop Phones
                   IP Phone 88xx Desktop Phones
                   Unified IP Conference Phone 8831
                   Wireless IP Phone 8821 and 8821-EX
Publisher:         Cisco Systems
Operating System:  Cisco
Impact/Access:     Root Compromise   -- Remote/Unauthenticated
                   Denial of Service -- Remote/Unauthenticated
Resolution:        Patch/Upgrade
CVE Names:         CVE-2020-3161  

Original Bulletin: 

Revision History:  April 17 2020: Exploitation and public announcements has been updated, 
                   as there is now public exploit code.
                   April 16 2020: Initial Release

- --------------------------BEGIN INCLUDED TEXT--------------------

Cisco IP Phones Web Server Remote Code Execution and Denial of Service

Priority:        Critical

Advisory ID:     cisco-sa-voip-phones-rce-dos-rB6EeRXs

First Published: 2020 April 15 16:00 GMT

Last Updated:    2020 April 16 15:57 GMT

Version 1.1:     Final

Workarounds:     No workarounds available

Cisco Bug IDs:   CSCuz03016CSCvs78272CSCvs78441



CVSS Score:


  o A vulnerability in the web server for Cisco IP Phones could allow an
    unauthenticated, remote attacker to execute code with root privileges or
    cause a reload of an affected IP phone, resulting in a denial of service
    (DoS) condition.

    The vulnerability is due to a lack of proper input validation of HTTP
    requests. An attacker could exploit this vulnerability by sending a crafted
    HTTP request to the web server of a targeted device. A successful exploit
    could allow the attacker to remotely execute code with root privileges or
    cause a reload of an affected IP phone, resulting in a DoS condition.

    Cisco has released software updates that address this vulnerability. There
    are no workarounds that address this vulnerability.

    This advisory is available at the following link:

Affected Products

  o Vulnerable Products

    This vulnerability affects the following Cisco products if they have web
    access enabled and are running a firmware release earlier than the first
    fixed release for that device:

       IP Phone 7811, 7821, 7841, and 7861 Desktop Phones
       IP Phone 8811, 8841, 8845, 8851, 8861, and 8865 Desktop Phones
       Unified IP Conference Phone 8831
       Wireless IP Phone 8821 and 8821-EX

    Note: Web access is disabled by default. Administrators can check the web
    access configuration from Cisco Unified Communications Manager by choosing
    Device > Phone > Select a Phone and checking whether Web Access is set to
    Enabled or Disabled . If it is set to Disabled , the IP phone is not

    For information about which Cisco firmware releases are vulnerable, see the
    Fixed Software section of this advisory.

    Products Confirmed Not Vulnerable

    Only products listed in the Vulnerable Products section of this advisory
    are known to be affected by this vulnerability.

    Cisco has confirmed that this vulnerability does not affect the following
    Cisco products:

       ATA 190 Analog Telephone Adapter
       ATA 191 Analog Telephone Adapter
       ATA 192 Multiplatform Analog Telephone Adapter
       IP Conference Phone 7832
       IP Conference Phone 7832 with Multiplatform Firmware
       IP Conference Phone 8832
       IP Conference Phone 8832 with Multiplatform Firmware
       IP DECT 6825 with Multiplatform Firmware
       IP Phone 6821, 6841, 6851, 6861, and 6871 with Multiplatform Firmware
       IP Phone 7811, 7821, 7841, and 7861 Desktop Phones with Multiplatform
       IP Phone 8811, 8841, 8845, 8851, 8861, and 8865 Desktop Phones with
        Multiplatform Firmware
       SPA112 2-Port Phone Adapter
       SPA122 ATA with Router
       SPA2102 Phone Adapter with Router
       SPA232D Multi-Line DECT ATA
       SPA3102 Voice Gateway with Router
       SPA8000 8-Port IP Telephony Gateway
       SPA8800 IP Telephony Gateway with 4 FXS and 4 FXO Ports
       Small Business SPA300 Series IP Phones
       Small Business SPA500 Series IP Phones
       Unified IP Conference Phone 8831 for Third-Party Call Control
       Unified IP Phone 6901 and 6911
       Unified SIP Phone 3905


  o There are no workarounds that address this vulnerability.

    However, if web access is not required, disabling it is considered a
    mitigation for this vulnerability. If web access is disabled, the phone is
    not vulnerable. For additional information, see the Web Access Disable
    chapter of the Phone Hardening guide.

    Note: Web access is disabled by default on Cisco IP phones.

Fixed Software

  o Cisco has released free software updates that address the vulnerability
    described in this advisory. Customers may only install and expect support
    for software versions and feature sets for which they have purchased a
    license. By installing, downloading, accessing, or otherwise using such
    software upgrades, customers agree to follow the terms of the Cisco
    software license: https://www.cisco.com/c/en/us/products/

    Additionally, customers may only download software for which they have a
    valid license, procured from Cisco directly, or through a Cisco authorized
    reseller or partner. In most cases this will be a maintenance upgrade to
    software that was previously purchased. Free security software updates do
    not entitle customers to a new software license, additional software
    feature sets, or major revision upgrades.

    When considering software upgrades , customers are advised to regularly
    consult the advisories for Cisco products, which are available from the
    Cisco Security Advisories and Alerts page , to determine exposure and a
    complete upgrade solution.

    In all cases, customers should ensure that the devices to be upgraded
    contain sufficient memory and confirm that current hardware and software
    configurations will continue to be supported properly by the new release.
    If the information is not clear, customers are advised to contact the Cisco
    Technical Assistance Center (TAC) or their contracted maintenance

    Customers Without Service Contracts

    Customers who purchase directly from Cisco but do not hold a Cisco service
    contract and customers who make purchases through third-party vendors but
    are unsuccessful in obtaining fixed software through their point of sale
    should obtain upgrades by contacting the Cisco TAC: https://www.cisco.com/c

    Customers should have the product serial number available and be prepared
    to provide the URL of this advisory as evidence of entitlement to a free

    Fixed Releases

    Customers are advised to upgrade to an appropriate fixed firmware release
    as indicated in the following table:

    Cisco IP Phone Model                            Cisco Bug  First Fixed
                                                    ID         Release
    IP Phone 7811, 7821, 7841, 7861 Desktop Phones  CSCuz03016 11.7(1)
    IP Phone 8811, 8841, 8845, 8851, 8861, 8865     CSCuz03016 11.7(1)
    Desktop Phones
    Unified IP Conference Phone 8831                CSCvs78441 10.3(1)SR6
    Wireless IP Phone 8821, 8821-EX                 CSCvs78272 11.0(5)SR3

    To download the Cisco IP Phone firmware from the Software Center on
    Cisco.com , do the following:

     1. Click Browse all .
     2. Choose Collaboration Endpoints > IP Phones .
     3. Choose a specific product from the right pane of the product selector.
     4. Choose a release from the left pane of the product page.

Exploitation and Public Announcements

  o The Cisco Product Security Incident Response Team (PSIRT) is aware that
    proof-of-concept exploit code is available for the vulnerability described
    in this advisory.


  o This vulnerability was found during internal security testing. Cisco would
    also like to thank Jacob Baines of Tenable for reporting this

Cisco Security Vulnerability Policy

  o To learn about Cisco security vulnerability disclosure policies and
    publications, see the Security Vulnerability Policy . This document also
    contains instructions for obtaining fixed software and receiving security
    vulnerability information from Cisco.


  o https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/

Revision History

  o +---------+------------------------+---------------+--------+-------------+
    | Version |      Description       |    Section    | Status |    Date     |
    |         | Updated Exploitation   |               |        |             |
    |         | and Public             | Exploitation  |        |             |
    | 1.1     | Announcements to       | and Public    | Final  | 2020-APR-16 |
    |         | indicate that there is | Announcements |        |             |
    |         | public exploit code.   |               |        |             |
    | 1.0     | Initial public         | -             | Final  | 2020-APR-15 |
    |         | release.               |               |        |             |

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