Summary

• A vulnerability in the web-based management interface of Cisco Expressway Series and Cisco TelePresence Video Communication Server (VCS) could allow an authenticated, remote attacker to execute arbitrary code on the underlying operating system as the root user.

  This vulnerability is due to incorrect handling of certain crafted software images that are uploaded to the affected device. An attacker could exploit this vulnerability by authenticating to the system as an administrative user and then uploading specific crafted software images to the affected device. A successful exploit could allow the attacker to execute arbitrary code on the underlying operating system as the root user.

  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:
  https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ewrce-QPynNCjh

Affected Products

• Vulnerable Products

  At the time of publication, this vulnerability affected Cisco Expressway Series and Cisco TelePresence VCS releases earlier than the first fixed release if they were running Release X8.6 or later.

  For information about which Cisco software releases are vulnerable, see the Fixed Software section of this advisory. See the Details section in the bug ID(s) at the top of this advisory for the most complete and current information.

  Products Confirmed Not Vulnerable

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

Workarounds

• There are no workarounds that address this vulnerability.

  While the following mitigations have been deployed and were proven successful in a test environment, customers should determine the applicability and effectiveness in their own environment and under their own use conditions. Customers should be aware that any workaround or mitigation that is implemented may negatively impact the functionality or performance of their network based on intrinsic customer deployment scenarios and limitations. Customers should not deploy any workarounds or mitigations before first evaluating the applicability to their own environment and any impact to such environment.

  Firewall Rule Modifications

  Access to the management plane of Cisco Expressway Series and Cisco TelePresence VCS should be restricted to trusted networks. Administrators can restrict access to the management ports (HTTPS/SSH) within the firewall rules on the device or by using an external firewall. The web UI port numbers can also be modified in the configuration.

  As a best practice, access to the management plane of Cisco Expressway Series and Cisco TelePresence VCS should not be exposed to the internet. For additional information, see the Intrusion Protection section of the Cisco Expressway Administrator Guide.

  Dedicated Management Interface

  As a best practice, access to the management plane of Cisco Expressway Series and Cisco TelePresence VCS should not be exposed to the internet. Beginning with Release X12.7, the product introduced a Dedicated Management Interface (DMI). Administrators can enable the DMI and implement the following configuration:

  • Allow the DMI to be the only interface used for management
  • Configure the DMI to be accessed only from trusted segments

  For additional information, see Configuring the Dedicated Management Interface (DMI) section of the Cisco Expressway Administrator Guide.

  Client Certificate-Based Security

  This vulnerability can be exploited only by an authenticated administrator. Using client authentication certificates helps prevent brute forcing of the administrative passwords. For additional information, see the Configuring Certificate-Based Authentication section of the Cisco Expressway Administrator Guide.

Fixed Software

• 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

  At the time of publication, Cisco Expressway Series and Cisco TelePresence VCS Release X14.0.3 and later contained the fix for this vulnerability.

  For information about fixed software releases, see the Details section in the bug ID(s) at the top of this advisory.

Recommendations

• Cisco recommends that customers upgrade to a fixed software release to address this vulnerability and implement the following best practices:

  • Not exposing the management plane to the internet
  • Changing all administrative passwords

  Cisco advises that customers who cannot upgrade to a fixed software release should immediately reinstall their current software release from a copy of software from Cisco.com and change any administrative passwords until they can upgrade to a fixed software release.

  Customers should follow best practices for the image downloaded from Cisco.com by validating the SHA512 checksum value, available on Cisco.com, prior to installing the downloaded software.

Exploitation and Public Announcements

• The Cisco Product Security Incident Response Team (PSIRT) is aware of malicious use of the vulnerability that is described in this advisory.

Source

• Cisco would like to thank Rui Ataide and Hermes Bojaxhi of NetWitness Incident Response Team for reporting this vulnerability.

URL

• https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ewrce-QPynNCjh

Revision History

• Version	Description	Section	Status	Date
  1.0	Initial public release.	—	Final	2021-AUG-18

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