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             AUSCERT External Security Bulletin Redistribution

         Cisco Expressway Software Unauthorized Access Information
                         Disclosure Vulnerability
                              21 January 2021


        AusCERT Security Bulletin Summary

Product:           Cisco Expressway Software
Publisher:         Cisco Systems
Operating System:  Cisco
Impact/Access:     Unauthorised Access -- Remote/Unauthenticated
Resolution:        Patch/Upgrade
CVE Names:         CVE-2020-3482  

Original Bulletin: 

Revision History:  January  21 2021: Vendor downgraded rating from medium to informationation
                   November 19 2020: Initial Release

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Cisco Expressway Software TURN Server Configuration Issue

Priority:        Informational
Advisory ID:     cisco-sa-Expressway-8J3yZ7hV
First Published: 2020 November 18 16:00 GMT
Last Updated:    2021 January 20 20:41 GMT
Version 2.0:     Final
Workarounds:     No workarounds available
Cisco Bug IDs:   CSCvt83751
CVE Names:       CVE-2020-3482
CWEs:            CWE-284


  o The Traversal Using Relays around NAT (TURN) server component of Cisco
    Expressway software supports the relay of media connections through a
    firewall using proxy services. As a result of this feature, interfaces such
    as the Cisco Expressway web administrative interface may become accessible
    from external networks.

    At the time of publication, documentation of the feature did not properly
    explain that users are able to bypass firewall protections that are
    designed to restrict access to the Cisco Expressway web administrative
    interface. However, an attacker must have credentials sufficient to use
    TURN services to be able to send network requests to the web administrative

    This advisory is available at the following link:

Affected Products

  o Vulnerable Products

    This issue impacts Cisco Expressway Series and Cisco TelePresence Video
    Communication Server (VCS) with the TURN server feature enabled.

    Products Confirmed Not Vulnerable

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

    Cisco has confirmed that Cisco Expressway Series and Cisco TelePresence VCS
    systems that do not have the TURN server feature enabled are not affected.


  o The Cisco Expressway IP Port Usage Configuration Guide recommends firewall
    configuration to prevent access to administrative ports from external
    networks. However, when TURN services are enabled, administrative ports are
    accessible through the TURN server from external networks. Customers should
    be aware that enabling the TURN services exposes administrative ports on
    the Cisco Expressway Series or Cisco TelePresence VCS host.


  o There are no workarounds that address this issue.

Exploitation and Public Announcements

  o The Cisco Product Security Incident Response Team (PSIRT) is not aware of
    any public announcements or malicious use of the issue that is described in
    this advisory.


  o Cisco would like to thank Christian Mehlmauer of WienCERT-IT-Security in
    the City of Vienna for reporting this issue.

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/cisco-sa-Expressway-8J3yZ7hV

Revision History

  o +---------+--------------------------+-------------+--------+-------------+
    | Version |       Description        |   Section   | Status |    Date     |
    |         | Changed the advisory SIR |             |        |             |
    |         | from Medium to           | Summary,    |        |             |
    |         | Informational. Updated   | Vulnerable  |        |             |
    | 2.0     | throughout to explain    | Products,   | Final  | 2021-JAN-20 |
    |         | that this not a          | Details,    |        |             |
    |         | vulnerability. Removed   | and Fixed   |        |             |
    |         | the Fixed Software       | Software    |        |             |
    |         | section.                 |             |        |             |
    |         | Included additional      |             |        |             |
    | 1.1     | information about the    | Affected    | Final  | 2020-NOV-25 |
    |         | vulnerable               | Products    |        |             |
    |         | configuration.           |             |        |             |
    | 1.0     | Initial public release.  | -           | Final  | 2020-NOV-18 |

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