AUSCERT External Security Bulletin Redistribution

                  ESB-2002.240 -- Cisco Security Advisory
              Multiple Vulnerabilities in Cisco IP Telephones
                                23 May 2002


        AusCERT Security Bulletin Summary

Product:                Cisco IP Phone 7910
                        Cisco IP Phone 7940
                        Cisco IP Phone 7960
Vendor:                 Cisco Systems
Impact:                 Denial of Service
                        Reduced Security
                        Administrator Compromise
Access Required:        Remote
                        Local (for Administrator Compromise)

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Cisco Security Advisory: Multiple Vulnerabilities in Cisco IP Telephones

Revision 1.0: INTERIM

For Public Release 2002 May 22 16:00 GMT

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    Affected Products
    Software Versions and Fixes
    Obtaining Fixed Software
    Exploitation and Public Announcements
    Status of This Notice
    Revision History
    Cisco Security Procedures

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Several vulnerabilities have been identified and repaired in Cisco IP Phones.
One vulnerability allows unauthorized modification of the phone's
configuration, while the remainder 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 

Affected Products

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


    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.
    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.
    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.


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

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

| CallManager | First Fixed Firmware  | First Fixed           |
| Version     | Release.              | CallManager Release.  |
| Affected    |                       |                       |
| 3.0         | P003J310              | N/A                   |
| 3.1         | P00303010401          | 3.1(4)                |
| 3.2         | P00303020203          | TBD                   |
|             | (available            |                       |
|             | 2002-05-29)           |                       |

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

| Version Affected | First Fixed Firmware Release.            |
| POS3-03-1-00 and | TBD                                      |
| earlier          |                                          |
| POM3-03-1-00 and | TBD                                      |
| earlier          |                                          |

Obtaining Fixed Software

Cisco is offering free software upgrades to address this vulnerability for all
affected customers. Customers may only install and expect support for the
feature sets they have purchased.

Customers with service contracts should contact their regular update channels
to obtain any software release containing the feature sets they have purchased.
For most customers with service contracts, this means that upgrades should be
obtained through the Software Center on Cisco's Worldwide Web site at 

Customers whose Cisco products are provided or maintained through a prior or
existing agreement with third-party support organizations such as Cisco
Partners, authorized resellers, or service providers should contact that
support organization for assistance with obtaining the free software upgrade(s).

Customers who purchased directly 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
obtain fixed software by contacting the Cisco Technical Assistance Center (TAC)
using the contact information listed below. In these cases, customers are
entitled to obtain an upgrade to a later version of the same release or as
indicated by the applicable row in the Software Versions and Fixes table (noted

Cisco 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

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

Please have your product serial number available and give the URL of this
notice as evidence of your entitlement to a free upgrade.

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


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

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

Status of This Notice: INTERIM

This is an interim notice. Although Cisco cannot guarantee the accuracy of all
statements in this notice, all of the facts have been checked to the best of
our ability. Cisco does not anticipate issuing updated versions of this notice
unless there is some material change in the facts. Should there be a
significant change in the facts, Cisco may update this notice.


This notice will be posted on Cisco's Worldwide Web site at 
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   |2002-May-22|Initial Public Release                           |
|1.0        |16:00 GMT  |                                                 |

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/warp/public/707/sec_incident_response.shtml. This includes
instructions for press inquiries regarding Cisco security notices. All Cisco
Security Advisories are available at http://www.cisco.com/go/psirt/.

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This notice is Copyright 2002 by Cisco Systems, Inc. This notice may be
redistributed freely after the release date given at the top of the text,
provided that redistributed copies are complete and unmodified, and include all
date and version information.

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Version: PGP 6.5.2


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