Cisco Security Advisory
Cisco Webex Meetings and Cisco Webex Meetings Server Ghost Join Vulnerability
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CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N/E:X/RL:X/RC:X
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A vulnerability in Cisco Webex Meetings and Cisco Webex Meetings Server could allow an unauthenticated, remote attacker to join a Webex session without appearing on the participant list.
This vulnerability is due to improper handling of authentication tokens by a vulnerable Webex site. An attacker could exploit this vulnerability by sending crafted requests to a vulnerable Cisco Webex Meetings or Cisco Webex Meetings Server site. A successful exploit requires the attacker to have access to join a Webex meeting, including applicable meeting join links and passwords. The attacker could then exploit this vulnerability to join meetings, without appearing in the participant list, while having full access to audio, video, chat, and screen sharing capabilities.
This advisory is available at the following link:
https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-webex-auth-token-3vg57A5r
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Vulnerable Products
This vulnerability affected all Cisco Webex Meetings sites prior to November 17, 2020. Webex Meetings is cloud based.
At the time of publication, this vulnerability also affected the following releases of Cisco Webex Meetings Server, which is on premises. See the Details section in the bug ID(s) at the top of this advisory for the most complete and current information.
- 3.0MR3 Security Patch 4 and earlier
- 4.0MR3 Security Patch 3 and earlier
Products Confirmed Not Vulnerable
Only products listed in the Vulnerable Products section of this advisory are known to be affected by this vulnerability.
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There are no workarounds that address this vulnerability.
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When considering software upgrades, customers are advised to regularly consult the advisories for Cisco products, which are available from the Cisco Security Advisories 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 providers.
Fixed Releases
Cisco has addressed this vulnerability in Cisco Webex Meetings sites, which are cloud based. No user action is required.
At the time of publication, the following releases for Cisco Webex Meetings Server, which is on-premises software, contained the fix for this vulnerability. Customers are advised to apply updated software releases. See the Details section in the bug ID(s) at the top of this advisory for the most complete and current information.
- 3.0MR3 Security Patch 5
- 4.0MR3 Security Patch 4
Customers who need additional information are advised to contact the Cisco TAC or their contracted maintenance providers.
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The Cisco Product Security Incident Response Team (PSIRT) is aware of public announcements about this vulnerability. Cisco PSIRT is not aware of malicious use of the vulnerability that is described in this advisory.
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Cisco would like to thank the following researchers from IBM Research for reporting this vulnerability:
- Jiyong Jang, Research Scientist and Manager
- Dhilung Kirat, Research Scientist
- Ian Molloy, Principal RSM and Department Head
- J.R. Rao, IBM Fellow and CTO
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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.
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Show LessVersion Description Section Status Date 1.4 Corrected 3.0MR to 3.0MR3. Vulnerable Products Final 2020-DEC-10 1.3 Removed mobile app from Vulnerable Products and Fixed Software. Updated formatting in Vulnerable Products and Fixed Software. Vulnerable Products and Fixed Software Final 2020-NOV-23 1.2 Updated affected software release. Vulnerable Products Final 2020-NOV-20 1.1 Corrected a researcher's name. Source Final 2020-NOV-19 1.0 Initial public release. - Final 2020-NOV-18
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