Wednesday, April 17, 2019

Cisco Expressway Series and Cisco TelePresence Video Communication Server Denial of Service Vulnerability

High
Advisory ID:
cisco-sa-20190417-es-tvcs-dos
First Published:
2019 April 17 16:00 GMT
Version 1.0:
Workarounds:
No workarounds available
Cisco Bug IDs:
CVE-2019-1721
CWE-20
CVSS Score:
Base 7.7Click Icon to Copy Verbose Score
CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:H/E:X/RL:X/RC:X
CVE-2019-1721
CWE-20

Summary

  • A vulnerability in the phone book feature of Cisco Expressway Series and Cisco TelePresence Video Communication Server (VCS) could allow an authenticated, remote attacker to cause the CPU to increase to 100% utilization, causing a denial of service (DoS) condition on an affected system.

    The vulnerability is due to improper handling of the XML input. An attacker could exploit this vulnerability by sending a Session Initiation Protocol (SIP) message with a crafted XML payload to an affected device. A successful exploit could allow the attacker to exhaust CPU resources, resulting in a DoS condition. Manual intervention may be required to recover the device.

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

    This advisory is available at the following link:
    https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20190417-es-tvcs-dos

Affected Products

  • Vulnerable Products

    This vulnerability affects Cisco Expressway Series and Cisco TelePresence Video Communication Server releases prior to X12.5.1.

    Administrators can log in to the web-based GUI of Cisco Expressway Series or Cisco TelePresence VCS and view the current version in the lower-right corner in the Version field. Alternatively, administrators can view the Software version field by navigating to Status > System > 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; however, there are two mitigation options.

    Option 1: Disable SIP if it’s not required
    Disabling SIP will completely close the attack vector for this vulnerability. However, it may not be suitable for all customers, as it is a required feature in many environments.

    To disable SIP from the web admin UI, navigate to Configuration > Protocols > SIP, and under the Configuration section, set SIP mode to Off and press the Save button.

    Option 2: Disable Provisioning services if it’s not required
    Disabling Provisioning services will completely close the attack vector for this vulnerability. However, it may not be suitable for all customers, as it is a required feature in many environments.

    To disable Provisioning services from the web admin UI, navigate to System > Administration settings, and under the Services section, set Provisioning services to Off and press the Save button.

Fixed Software

  • Cisco has released free software updates that address the vulnerability described in this advisory. 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.

    When considering software upgrades, customers are advised to regularly consult the advisories for Cisco products, which are available from the Cisco Security Advisories and Alerts 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

    This vulnerability is fixed in Cisco Expressway Series and Cisco TelePresence Video Communication Server Releases X12.5.1 and later.

Exploitation and Public Announcements

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

Source

  • This vulnerability was found during internal security testing.

Cisco Security Vulnerability Policy

  • 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.

Subscribe to Cisco Security Notifications

URL

Revision History

  • Version Description Section Status Date
    1.0 Initial public release. — Final 2019-April-17
    Show Less

Cisco Security Vulnerability Policy

  • 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.

Subscribe to Cisco Security Notifications



from Cisco Security Advisory http://bit.ly/2VRUukD
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