Summary

• A vulnerability in the call-handling functionality of Session Initiation Protocol (SIP) Software for Cisco IP Phone 7800 Series and 8800 Series could allow an unauthenticated, remote attacker to cause an affected phone to reload unexpectedly, resulting in a temporary denial of service (DoS) condition.

  The vulnerability is due to incomplete error handling when XML data within a SIP packet is parsed. An attacker could exploit this vulnerability by sending a SIP packet that contains a malicious XML payload to an affected phone. A successful exploit could allow the attacker to cause the affected phone to reload unexpectedly, resulting in a temporary DoS condition.

  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-20190501-phone-sip-xml-dos

Affected Products

• Vulnerable Products

  This vulnerability affects the following Cisco products if they are running a SIP Software release prior to the first fixed release:

  • IP Conference Phone 7832
  • IP Conference Phone 8832
  • IP Phone 7811
  • IP Phone 7821
  • IP Phone 7841
  • IP Phone 7861
  • IP Phone 8811
  • IP Phone 8841
  • IP Phone 8845
  • IP Phone 8851
    
  • IP Phone 8861
  • IP Phone 8865
  • Unified IP 8831 Conference Phone¹
  • Unified IP 8831 Conference Phone for Third-Party Call Control²
  • Wireless IP Phone 8821
  • Wireless IP Phone 8821-EX

  ¹ The fix for Cisco Unified IP 8831 Conference Phone is targeted for late 2019.
  ² No fix is available for Cisco Unified IP 8831 Conference Phone for Third-Party Call Control.

  Products Confirmed Not Vulnerable

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

  Cisco has confirmed that IP Phones running Multiplatform Firmware are not affected by this vulnerability.

Workarounds

• There are no workarounds that address this vulnerability.

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

  Cisco fixed this vulnerability in the following SIP Software releases:

  • 11.0(5) and later for Cisco Wireless IP Phone 8821 and 8821-EX
  • 12.5(1) and later for the rest of the Cisco IP Phone 7800 Series and 8800 Series^1,2

  1. The fix for Cisco Unified IP 8831 Conference Phone is targeted for late 2019.
  2. No fix is available for Cisco Unified IP 8831 Conference Phone for Third-Party Call Control.

  Customers can download the SIP Software from the Software Center on Cisco.com by doing the following:

  1. Click Browse all.
  2. Choose Collaboration Endpoints > IP Phones > IP Phone 7800 Series or IP Phone 8800 Series > [Model] > Session Initiation Protocol (SIP) Software.
  3. Access releases by using the left pane of the page.

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 the resolution of a Cisco TAC support case.

URL

• https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20190501-phone-sip-xml-dos

Revision History

• Version	Description	Section	Status	Date
  1.0	Initial public release.	—	Final	2019-May-01

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