Cisco Security Advisory
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CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:X/RL:X/RC:X
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A vulnerability in the web server for Cisco IP Phones could allow an unauthenticated, remote attacker to execute code with root privileges or cause a reload of an affected IP phone, resulting in a denial of service (DoS) condition.
The vulnerability is due to a lack of proper input validation of HTTP requests. An attacker could exploit this vulnerability by sending a crafted HTTP request to the web server of a targeted device. 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 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-voip-phones-rce-dos-rB6EeRXs
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Vulnerable Products
This vulnerability affects the following Cisco products if they have web access enabled and are running a firmware release earlier than the first fixed release for that device:
- IP Phone 7811, 7821, 7841, and 7861 Desktop Phones
- IP Phone 8811, 8841, 8845, 8851, 8861, and 8865 Desktop Phones
- Unified IP Conference Phone 8831
- Wireless IP Phone 8821 and 8821-EX
Note: Web access is disabled by default. Administrators can check the web access configuration from Cisco Unified Communications Manager by choosing Device > Phone > Select a Phone and checking whether Web Access is set to Enabled or Disabled. If it is set to Disabled, the IP phone is not vulnerable.
For information about which Cisco firmware 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 Conference Phone 7832
- IP Conference Phone 7832 with Multiplatform Firmware
- IP Conference Phone 8832
- IP Conference Phone 8832 with Multiplatform Firmware
- IP DECT 6825 with Multiplatform Firmware
- IP Phone 6821, 6841, 6851, 6861, and 6871 with Multiplatform Firmware
- IP Phone 7811, 7821, 7841, and 7861 Desktop Phones with Multiplatform Firmware
- IP Phone 8811, 8841, 8845, 8851, 8861, and 8865 Desktop Phones with Multiplatform Firmware
- SPA112 2-Port Phone Adapter
- SPA122 ATA with Router
- SPA2102 Phone Adapter with Router
- SPA232D Multi-Line DECT ATA
- SPA3102 Voice Gateway with Router
- SPA8000 8-Port IP Telephony Gateway
- SPA8800 IP Telephony Gateway with 4 FXS and 4 FXO Ports
- Small Business SPA300 Series IP Phones
- Small Business SPA500 Series IP Phones
- Unified IP Conference Phone 8831 for Third-Party Call Control
- Unified IP Phone 6901 and 6911
- Unified SIP Phone 3905
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There are no workarounds that address this vulnerability.
However, if web access is not required, disabling it is considered a mitigation for this vulnerability. If web access is disabled, the phone is not vulnerable. For additional information, see the Web Access Disable chapter of the Phone Hardening guide.
Note: Web access is disabled by default on Cisco IP phones.
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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 Phone 7811, 7821, 7841, 7861 Desktop Phones CSCuz03016 11.7(1) IP Phone 8811, 8841, 8845, 8851, 8861, 8865 Desktop Phones CSCuz03016 11.7(1) Unified IP Conference Phone 8831 CSCvs78441 10.3(1)SR6 Wireless IP Phone 8821, 8821-EX CSCvs78272 11.0(5)SR3 To download the Cisco IP Phone firmware from the Software Center on Cisco.com, do the following:
- Click Browse all.
- Choose Collaboration Endpoints > IP Phones.
- Choose a specific product from the right pane of the product selector.
- Choose a release from the left pane of the product page.
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The Cisco Product Security Incident Response Team (PSIRT) is aware that proof-of-concept exploit code is available for the vulnerability described in this advisory.
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This vulnerability was found during internal security testing. Cisco would also like to thank Jacob Baines of Tenable for reporting this vulnerability.
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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.
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Show LessVersion Description Section Status Date 1.1 Updated Exploitation and Public Announcements to indicate that there is public exploit code. Exploitation and Public Announcements Final 2020-APR-16 1.0 Initial public release. — Final 2020-APR-15
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