Summary

• A vulnerability in the Cisco Discovery Protocol implementation for the Cisco IP Phone could allow an unauthenticated, adjacent attacker to remotely execute code with root privileges or cause a reload of an affected IP phone.

  The vulnerability is due to missing checks when processing Cisco Discovery Protocol messages. An attacker could exploit this vulnerability by sending a crafted Cisco Discovery Protocol packet to the targeted IP phone. A successful exploit could allow the attacker to remotely execute code with root privileges or cause a reload of an affected IP phone, resulting in a denial of service (DoS) condition.

  Note: Cisco Discovery Protocol is a Layer 2 protocol. To exploit this vulnerability, an attacker must be in the same broadcast domain as the affected device (Layer 2 adjacent).

  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-20200205-voip-phones-rce-dos

Affected Products

• Vulnerable Products

  This vulnerability affects the following Cisco IP phones with Cisco Discovery Protocol enabled¹ and running a vulnerable firmware release:

  • IP Conference Phone 7832
  • IP Conference Phone 7832 with Multiplatform Firmware
  • IP Conference Phone 8832
  • IP Conference Phone 8832 with Multiplatform Firmware
  • IP Phone 6821, 6841, 6851, 6861, 6871 with Multiplatform Firmware
  • IP Phone 7811, 7821, 7841, 7861 Desktop Phones
  • IP Phone 7811, 7821, 7841, 7861 Desktop Phones with Multiplatform Firmware
  • IP Phone 8811, 8841, 8851, 8861, 8845, 8865 Desktop Phones
  • IP Phone 8811, 8841, 8851, 8861, 8845, 8865 Desktop Phones with Multiplatform Firmware
  • Unified IP Conference Phone 8831
  • Unified IP Conference Phone 8831 for Third-Party Call Control
  • Wireless IP Phone 8821, 8821-EX

  ¹Cisco Discovery Protocol is enabled by default on most IP Phone models.

  For information about which 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 this vulnerability.

  Cisco has confirmed that this vulnerability does not affect the following Cisco products:

  • ATA 190 Analog Telephone Adapter
  • ATA 191 Analog Telephone Adapter
  • ATA 192 Multiplatform Analog Telephone Adapter
  • IP DECT 6825 with Multiplatform Firmware
  • SPA112 2-Port Phone Adapter
  • SPA122 ATA with Router
  • SPA2102 Phone Adapter with Router
  • SPA232D Multi-Line DECT ATA
  • Small Business SPA300 Series IP Phones
  • Small Business SPA500 Series IP Phones
  • SPA3102 Voice Gateway with Router
  • SPA8000 8-port IP Telephony Gateway
  • SPA8800 IP Telephony Gateway with 4 FXS and 4 FXO Ports
  • Unified IP Phone 6901
  • Unified IP Phone 7942
  • Unified IP Phone 7945
  • Unified IP Phone 7962
  • Unified IP Phone 7965
  • Unified IP Phone 7975
  • Unified SIP Phone 3905

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 

  Customers are advised to upgrade to an appropriate fixed firmware release as indicated in the following table:

  Cisco IP Phone Model	Cisco Bug ID	First Fixed Release
  IP Conference Phone 7832	CSCvr96069	12.7(1)
  IP Conference Phone 7832 with Multiplatform Firmware	CSCvr96060	11.3(1)SR1
  IP Conference Phone 8832	CSCvr96071	12.7(1)
  IP Conference Phone 8832 with Multiplatform Firmware	CSCvr96064	11.3(1)SR1
  IP Phone 6821, 6841, 6851, 6861, 6871 with Multiplatform Firmware	CSCvr96065, CSCvr96067	11.3(1)SR1
  IP Phone 7811, 7821, 7841, 7861 Desktop Phones	CSCvr96739	12.7(1)
  IP Phone 7811, 7821, 7841, 7861 Desktop Phones with Multiplatform Firmware	CSCvr96063	11.3(1)SR1
  IP Phone 8811, 8841, 8851, 8861, 8845, 8865 Desktop Phones	CSCvr96066, CSCvr96069	12.7(1)
  IP Phone 8811, 8841, 8851, 8861, 8845, 8865 Desktop Phones with Multiplatform Firmware	CSCvr96058, CSCvr96059	11.3(1)SR1
  Unified IP Conference Phone 8831	CSCvr96738	10.3(1)SR6 (Targeted for March 2020)
  Unified IP Conference Phone 8831 for Third-Party Call Control	CSCvr96057	There is no fixed firmware available at this time.
  Wireless IP Phone 8821 and 8821-EX	CSCvr96070	11.0(5)SR2

  To download the Cisco IP Phone firmware from the Software Center on Cisco.com, do the following:

  1. Click Browse all.
  2. Choose Collaboration Endpoints > IP Phones.
  3. Choose a specific product from the right pane of the product selector.
  4. Choose a release from the left pane of the product page.

Exploitation and Public Announcements

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

Source

• Cisco would like to thank Ben Seri, VP of Research at Armis, for finding and reporting this vulnerability.

URL

• https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20200205-voip-phones-rce-dos

Revision History

• Version	Description	Section	Status	Date
  1.4	Added the Cisco ATA 190 Analog Telephone Adapter product as not vulnerable.	Products Confirmed Not Vulnerable	Final	2020-February-25
  1.3	Added the Cisco Unified SIP Phone 3905 and Cisco Unified IP Phone 6901 as confirmed not vulnerable.	Products Confirmed Not Vulnerable	Final	2020-February-20
  1.2	Added the Cisco ATA191 and ATA 192 products as not vulnerable. Listed the specific models of the 7900 phones that are confirmed not vulnerable.	Products Confirmed Not Vulnerable	Final	2020-February-14
  1.1	Added the Cisco Unified IP Phone 7900 Series as not vulnerable.	Products Confirmed Not Vulnerable	Final	2020-February-11
  1.0	Initial public release.	—	Final	2020-February-05

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