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             AUSCERT External Security Bulletin Redistribution

                  Cisco Webex Meetings Enumeration Attack
                              2 October 2019


        AusCERT Security Bulletin Summary

Product:           Cisco Webex Meetings
Publisher:         Cisco Systems
Operating System:  Windows
                   UNIX variants (UNIX, Linux, OSX)
Impact/Access:     Access Confidential Data -- Remote/Unauthenticated
Resolution:        Mitigation

Original Bulletin: 

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Cisco Webex Meetings Enumeration Attack

Priority:        Informational

Advisory ID:     cisco-sa-20191001-webex-enum

First Published: 2019 October 1 13:00 GMT

Version 1.0:     Final

Workarounds:     Yes


  o Cisco Webex Meetings is an enterprise solution for hosting online meetings
    that offers video conferencing, screen sharing, and webinar capabilities
    that support hundreds of participants. Cisco Webex Meetings utilizes a
    nine-digit number as a user-friendly meeting identifier that can be easily
    typed in to join a meeting from all types of endpoints.

    On July 24th, 2019, Shreyans Mehta of Cequence Security and the CQ Prime
    Research Team reported to Cisco that an attacker could take advantage of
    one of the Webex Meetings API calls to enumerate all the meeting numbers in
    use by an organization on the platform at a certain moment in time.

    This advisory is available at the following link:

Affected Products

  o Vulnerable Products

    The issue described in this advisory affects Cisco Webex Meetings.

    Products Confirmed Not Vulnerable

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

    Cisco has confirmed that Cisco Webex Meeting Server, used for on-premise
    deployments, does not exhibit this behavior.


  o As part of the process of creating a meeting, Webex will randomly generate
    and assign a nine-digit identifier that invitees can later use to join the

    Shreyans Mehta of Cequence Security and the CQ Prime Research Team have
    reported to Cisco that one of the Webex API calls could be used to
    enumerate all of the meeting numbers for ongoing or future meetings. The
    response to the invoked API call would allow an attacker to determine:

       Whether a certain meeting number is in use, and
       Whether the meeting is password protected

    The attacker could use the gathered information to try to join meetings
    that are not password protected. If the attacker was to join the meeting
    using this information, they would still be listed as a participant and
    could be expelled by the host. For password-protected meetings, the
    attacker could recover the meeting number, but would not be able to uncover
    the meeting title, schedule or host name, or join the meeting.


  o The most effective step to strengthen the security of all meetings is to
    require a password. Passwords protect against unauthorized attendance
    because only users with access to the password are able to join.

    Cisco recommends that administrators maintain their sites with the default
    configuration that makes using a password mandatory when users are setting
    up a meeting. This recommendation, with other security best practices, is
    documented in the guide Cisco WebEx Best Practices for Secure Meetings for
    Site Administrators and Hosts .

    Cisco Webex offers a default, randomly generated password as part of the
    meeting setup process in sites that do not mandate password protection.
    Customers are able to override this password with a user-defined password
    or disable password protection if the site allows it.

Exploitation and Public Announcements

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


  o Cisco would like to thank Shreyans Mehta of Cequence Security and the CQ
    Prime Research Team for reporting this attack method.

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       |
    | 1.0     | Initial public release.  | -       | Final  | 2019-October-01 |

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