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Category:   Device (VoIP/Phone/FAX)  >   Cisco IP Phones Vendors:   Cisco
Cisco IP Phones Allow Remote Users to Cause the Phone to Crash and Restart and Allow Physically Local Users to Modify the Telephone's Configuration
SecurityTracker Alert ID:  1004356
SecurityTracker URL:
CVE Reference:   GENERIC-MAP-NOMATCH   (Links to External Site)
Date:  May 22 2002
Impact:   Denial of service via network, Modification of system information, Root access via local system
Fix Available:  Yes  Vendor Confirmed:  Yes  Exploit Included:  Yes  
Version(s): 7910, 7940, and 7960
Description:   Several vulnerabilities were reported in Cisco's IP Phones. A physically local user may be able to modify a telephone's configuration. A remote user can cause the phone to restart.

Cisco reported that IP Phone models 7910, 7940, and 7960 contains vulnerabilities.

According to the report, the IP Phones can be made to restart by remote users conducting network-based denial of service attacks, using tools such as "jolt", "jolt2", "raped", "hping2", "bloop", "bubonic", "mutant", "trash", and "trash2". A remote user can also send a specially crafted HTTP request to an IP Phone's built-in web server to cause the phone to reinitialize. This is reportedly due to an input validation flaw. When the phone restarts, any call in progress on the affected IP Phone will be disconnected and the phone will not be useable until it has finished restarting. A remote user can repeat these exploits to cause denial of service conditions to persist over a period of time.

A physically local user can access and change the phone's configuration via the "Settings" button on the phone by unlocking the settings using a trusted path key combination: '**#'. The local user may be able to cause the phone to download user-supplied software or configuration information. According to the report, the local user could gain full control over the operation of the phone and any call setup requests and responses made between the IP Phone and Cisco CallManagers or other voice-over-IP (VoIP) gateways.

Cisco credits Johnathan Nightingale with reporting some of these bugs (CSCdx21102 and CSCdx21108).

Impact:   A remote user can cause the phone to restart, disrupting any calls in progress until the phone has completed the restart process. A physically local user can modify the phone's configuration to take full control of the phone.
Solution:   The vendor has issued fixes for some of the affected versions.

For 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

For 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

Customers can obtain these fixes through their normal upgrade channels. For more information on obtaining the appropriate fix, see the Cisco advisory at:

Vendor URL: (Links to External Site)
Cause:   Authentication error, Exception handling error, Input validation error

Message History:   None.

 Source Message Contents

Subject:  Cisco Security Advisory: Multiple Vulnerabilities in Cisco IP Telephones


Cisco Security Advisory: Multiple Vulnerabilities in Cisco IP Telephones
Revision 1.0: Interim
For Public Release 2002 May 22 16:00 GMT


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 

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

Software Versions and Fixes

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

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

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 above). 

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) 
See for
additional TAC contact information, including special localized
telephone numbers, instructions, and e-mail addresses for use in various

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 "" or
"" 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 administrators. 

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: 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: (includes CERT/CC) 
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 1.0 2002-May-22 16:00 GMT 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 This
includes instructions for press inquiries regarding Cisco security
notices. All Cisco Security Advisories are available at 


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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