Guest

Products & Services

Multiple Vulnerabilities in Cisco IP Telephones

Advisory ID: cisco-sa-20020522-ip-phone-vulnerability

http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20020522-ip-phone-vulnerability

Revision 1.1

For Public Release 2002 May 22 16:00  UTC (GMT)


Summary

Several vulnerabilities have been identified and repaired in Cisco IP Phones. One vulnerability allows unauthorized modification of the phone's configuration, while the remainders cause the phone to restart when certain types of network traffic are received.

Workarounds are available for some of the vulnerabilities. Cisco is offering free fixed software to address these vulnerabilities. Full details are available below and in the on-line copy of this document at http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20020522-ip-phone-vulnerability

Affected Products

This section provides details on affected products.

Vulnerable Products

Cisco IP Phone models 7910, 7940, and 7960 are the only Cisco products affected by these vulnerabilities.

Products Confirmed Not Vulnerable

No other Cisco products are currently known to be affected by these vulnerabilities.

Details

CSCdw16714

CSCdw16720

CSCdw95128

CSCdv29136

The Cisco IP Phones are vulnerable to several network based Denial of Service (DoS) attacks including the well-known attacks for "jolt", "jolt2", "raped", "hping2", "bloop", "bubonic", "mutant", "trash", and "trash2". All of these defects were resolved by improving the ability of the IP Phone to resist high rates of traffic directed at the IP Phone.

CSCdw93296

CSCdx21102

The Cisco IP phones include a built-in web server on port 80. The server provides several pages of debug and status information about the phone. It is possible to modify an HTTP request to exploit an input validation vulnerability which results in the reinitialization of the IP phone.

CSCdx21108

The Cisco IP Phones store their configuration information locally and most of it is accessible through the "Settings" button on the phone. By default, these settings are locked (as indicated by a padlock icon in the mode title bar when viewing them) to prevent them from being changed accidentally. These settings may be modified via a trusted path key combination: '**#'. This is documented in the product manual and is not admin-configurable. Once unlocked, several fields can be reconfigured. Modification of the phone's configuration is very likely to go unnoticed, since a user never has to interact with the configuration menu where these changes were made. This will be resolved at a later date likely by a configuration option to control the ability to make local configuration changes at the keypad of the phone.

Vulnerability Scoring Details

Cisco has provided scores for the vulnerabilities in this advisory based on the Common Vulnerability Scoring System (CVSS). The CVSS scoring in this Security Advisory is done in accordance with CVSS version 2.0.

CVSS is a standards-based scoring method that conveys vulnerability severity and helps determine urgency and priority of response.

Cisco has provided a base and temporal score. Customers can then compute environmental scores to assist in determining the impact of the vulnerability in individual networks.

Cisco has provided an FAQ to answer additional questions regarding CVSS at
http://www.cisco.com/web/about/security/intelligence/cvss-qandas.html .

Cisco has also provided a CVSS calculator to help compute the environmental impact for individual networks at
http://intellishield.cisco.com/security/alertmanager/cvss .


Impact

Cisco IP Phones can be forced to restart by an attacker using any of a variety of widely available, well-known DOS programs if the attacker can successfully transmit packets to the IP Telephone. The phone may also restart in the event it receives a crafted HTTP request with invalid arguments directed at the phone. Any call in progress on the affected IP Phone will be disconnected, and the IP Phone will not be useable until it has finished restarting and resumed normal operation. This attack can be repeated indefinitely.

Cisco IP phones running a SIP or MGCP image are subject to the same widely available denial-of-service programs but are not susceptible to a web-based attack as those images do not include a web interface.

Normal operation of Cisco IP Phones can be subverted if an attacker obtains local physical access to the IP Phone and reconfigures it, possibly forcing it to download software or configuration information of his or her own choosing. A successful attacker could gain full control over the operation of the IP Phone and any call setup requests and responses made between the IP Phone and Cisco CallManagers or other VoIP gateways.

Software Versions and Fixes

When considering software upgrades, also consult http://www.cisco.com/go/psirt and any subsequent advisories to determine exposure and a complete upgrade solution.

In all cases, customers should exercise caution to be certain the devices to be upgraded contain sufficient memory and that current hardware and software configurations will continue to be supported properly by the new release. If the information is not clear, contact the Cisco Technical Assistance Center ("TAC") or your contracted maintenance provider for assistance.

Cisco IP Phone Firmware (fixes carry forward into all later versions)

CallManager Version Affected

First Fixed Firmware Release.

First Fixed CallManager Release.

3.0

P003J310

N/A

3.1

P00303010401

3.1(4)

3.2

P00303020203 (available 2002-05-29)

TBD

Cisco IP Phone SIP or MGCP Firmware (fixes carry forward into all later versions)

Version Affected

First Fixed Firmware Release.

POS3-03-1-00 and earlier

TBD

POM3-03-1-00 and earlier

TBD

Workarounds

Denial-of-service attacks on the Cisco IP Phone can be mitigated by limiting or blocking IP traffic from untrusted sources. Exploitation of the web interface vulnerability can be provided by blocking access to port 80 via other devices on the network. The basic configuration of the Cisco IP Telephone can be protected by permitting physical access only by authorized users and network administrators.

Obtaining Fixed Software

Cisco has made free software available to address this vulnerability for affected customers. Prior to deploying software, customers should consult their maintenance provider or check the software for feature set compatibility and known issues specific to their environment.

Customers may only install and expect support for the feature sets they have purchased. By installing, downloading, accessing or otherwise using such software upgrades, customers agree to be bound by the terms of Cisco's software license terms found at http://www.cisco.com/public/sw-license-agreement.html, or as otherwise set forth at Cisco.com Downloads at http://www.cisco.com/public/sw-center/sw-usingswc.shtml.

Do not contact either "psirt@cisco.com" or "security-alert@cisco.com" for software upgrades.

Customers with Service Contracts

Customers with contracts should obtain upgraded software through their regular update channels. For most customers, this means that upgrades should be obtained through the Software Center on Cisco's worldwide website at http://www.cisco.com.

Customers using Third Party Support Organizations

Customers whose Cisco products are provided or maintained through prior or existing agreement with third-party support organizations such as Cisco Partners, authorized resellers, or service providers should contact that support organization for guidance and assistance with the appropriate course of action in regards to this advisory.

The effectiveness of any workaround or fix is dependent on specific customer situations such as product mix, network topology, traffic behavior, and organizational mission. Due to the variety of affected products and releases, customers should consult with their service provider or support organization to ensure any applied workaround or fix is the most appropriate for use in the intended network before it is deployed.

Customers without Service Contracts

Customers who purchase direct from Cisco but who do not hold a Cisco service contract and customers who purchase through third-party vendors but are unsuccessful at obtaining fixed software through their point of sale should get their upgrades by contacting the Cisco Technical Assistance Center (TAC). TAC contacts are as follows.

  • +1 800 553 2447 (toll free from within North America)
  • +1 408 526 7209 (toll call from anywhere in the world)
  • e-mail: tac@cisco.com

Have your product serial number available and give the URL of this notice as evidence of your entitlement to a free upgrade. Free upgrades for non-contract customers must be requested through the TAC.

Refer to http://www.cisco.com/warp/public/687/Directory/DirTAC.shtml for additional TAC contact information, including special localized telephone numbers and instructions and e-mail addresses for use in various languages.

Exploitation and Public Announcements

The vulnerabilities described by CSCdx21102 and CSCdx21108 were originally reported to Cisco by Johnathan Nightingale. The Cisco PSIRT is not aware of any public announcements or malicious use of the vulnerabilities described in this advisory.

Status of this Notice: Final

THIS DOCUMENT IS PROVIDED ON AN "AS IS" BASIS AND DOES NOT IMPLY ANY KIND OF GUARANTEE OR WARRANTY, INCLUDING THE WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR USE. YOUR USE OF THE INFORMATION ON THE DOCUMENT OR MATERIALS LINKED FROM THE DOCUMENT IS AT YOUR OWN RISK. CISCO RESERVES THE RIGHT TO CHANGE OR UPDATE THIS DOCUMENT AT ANY TIME.

A stand-alone copy or Paraphrase of the text of this document that omits the distribution URL in the following section is an uncontrolled copy, and may lack important information or contain factual errors.


Distribution

This notice will be posted on Cisco's Worldwide Web site at http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20020522-ip-phone-vulnerability. In addition to Worldwide Web posting, a text version of this notice is clear-signed with the Cisco PSIRT PGP key and is posted to the following e-mail and Usenet news recipients:

  • cust-security-announce@cisco.com
  • bugtraq@securityfocus.com
  • first-teams@first.org (includes CERT/CC)
  • cisco@spot.colorado.edu
  • cisco-nsp@puck.nether.net
  • comp.dcom.sys.cisco
  • firewalls@lists.gnac.com
  • Various internal Cisco mailing lists

Future updates of this notice, if any, will be placed on Cisco's Worldwide Web server, but may or may not be actively announced on mailing lists or newsgroups. Users concerned about this problem are encouraged to check the URL given above for any updates.


Revision History

Revision 1.1

2002-July-31

Change status from Interim to Final

Revision 1.0

2002-May-22

Initial public release

Cisco Security Procedures

Complete information on reporting security vulnerabilities in Cisco products, obtaining assistance with security incidents, and registering to receive security information from Cisco, is available on Cisco's Worldwide Web site at http://www.cisco.com/web/about/security/psirt/security_vulnerability_policy.html. This includes instructions for press inquiries regarding Cisco security notices. All Cisco Security Advisories are available at http://www.cisco.com/go/psirt/.