Summary

• Multiple vulnerabilities in the API and in the web-based management interface of Cisco Expressway Series and Cisco TelePresence Video Communication Server (VCS) could allow a remote attacker to overwrite arbitrary files or conduct null byte poisoning attacks on an affected device.

  Note: Cisco Expressway Series refers to the Expressway Control (Expressway-C) device and the Expressway Edge (Expressway-E) device.

  For more information about these vulnerabilities, see the Details section of this advisory.

  Cisco has released software updates that address these vulnerabilities. There are no workarounds that address these vulnerabilities.

  This advisory is available at the following link:
  https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-expressway-overwrite-3buqW8LH

Affected Products

• Vulnerable Products

  These vulnerabilities affect Cisco Expressway Series software and Cisco TelePresence VCS software if they are in the default configuration.

  For information about which Cisco software 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 these vulnerabilities.

Details

• The vulnerabilities are not dependent on one another. Exploitation of one of the vulnerabilities is not required to exploit another vulnerability. In addition, a software release that is affected by one of the vulnerabilities may not be affected by the other vulnerabilities.

  Details about the vulnerabilities are as follows:

  CVE-2022-20812: Cisco Expressway Series and Cisco TelePresence VCS Arbitrary File Overwrite Vulnerability

  A vulnerability in the cluster database API of Cisco Expressway Series and Cisco TelePresence VCS could allow an authenticated, remote attacker with Administrator read-write privileges on the application to conduct absolute path traversal attacks on an affected device and overwrite files on the underlying operating system as a root user.
  
  This vulnerability is due to insufficient input validation of user-supplied command arguments. An attacker could exploit this vulnerability by authenticating to the system as an administrative read-write user and submitting crafted input to the affected command. A successful exploit could allow the attacker to overwrite arbitrary files 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.

  Bug ID(s): CSCwa01085
  CVE ID: CVE-2022-20812
  Security Impact Rating (SIR): Critical
  CVSS Base Score: 9.0
  CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:L

  CVE-2022-20813: Cisco Expressway Series and Cisco TelePresence VCS Null Byte Poisoning Vulnerability

  A vulnerability in the certificate validation of Cisco Expressway Series and Cisco TelePresence VCS could allow an unauthenticated, remote attacker to gain unauthorized access to sensitive data.

  This vulnerability is due to improper certificate validation. An attacker could exploit this vulnerability by using a man-in-the-middle technique to intercept the traffic between devices, and then using a crafted certificate to impersonate the endpoint. A successful exploit could allow the attacker to view the intercepted traffic in clear text or alter the contents of the traffic.

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

  Bug ID(s): CSCwa01080
  CVE ID: CVE-2022-20813
  Security Impact Rating (SIR): High
  CVSS Base Score: 7.4
  CVSS Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N

Workarounds

• There are no workarounds that address these vulnerabilities.

Fixed Software

• Cisco has released free software updates that address the vulnerabilities described in this advisory. Customers with service contracts that entitle them to regular software updates should obtain security fixes through their usual update channels.

  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/end-user-license-agreement.html

  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.

  The Cisco Support and Downloads page on Cisco.com provides information about licensing and downloads. This page can also display customer device support coverage for customers who use the My Devices tool.

  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.

  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/en/us/support/web/tsd-cisco-worldwide-contacts.html

  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 upgrade.

  Fixed Releases

  In the following table(s), the left column lists Cisco software releases. The right column indicates whether a release is affected by the vulnerabilities that are described in this advisory and the first release that includes the fix for these vulnerabilities. Customers are advised to upgrade to an appropriate fixed software release as indicated in this section.

  Cisco Expressway Series and Cisco TelePresence VCS Release	First Fixed Release
  Earlier than 14.0	Migrate to a fixed release.
  14.0	14.31 (late Apr 2023)

  1. A partial fix was provided in Release 14.0.7. For complete coverage, customers should upgrade to Release 14.3 or higher.

  The Cisco Product Security Incident Response Team (PSIRT) validates only the affected and fixed release information that is documented in this advisory.

Exploitation and Public Announcements

• The Cisco PSIRT is not aware of any public announcements or malicious use of the vulnerabilities that are described in this advisory.

Source

• CVE-2022-20812 was found during internal security testing by Jason Crowder of the Cisco Advanced Security Initiatives Group (ASIG).

  CVE-2022-20813 was found during internal security testing by Deklan Evans of the Cisco ASIG.

URL

• https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-expressway-overwrite-3buqW8LH

Revision History

• Version	Description	Section	Status	Date
  1.1	Updated fixed release table.	Fixed Releases	Final	2023-APR-04
  1.0	Initial public release.	-	Final	2022-JUL-06

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