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             AUSCERT External Security Bulletin Redistribution

                 ESB-2005.0256 -- Cisco Security Advisory
              Cisco IPSec Malformed IKE Packet Vulnerability
                               31 March 2005


        AusCERT Security Bulletin Summary

Product:           Cisco Catalyst 6500 Series
                   Cisco 7600 Series
Publisher:         Cisco Systems
Operating System:  Cisco IOS 12.2SXA, 12.2SXB, 12.2SX, 12.2SY
Impact:            Denial of Service
Access:            Remote/Unauthenticated
CVE Names:         CAN-2004-0710

Ref:               ESB-2004.0262

Original Bulletin: http://www.cisco.com/warp/public/707/cisco-sa-20040408-vpnsm.shtml

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Cisco Security Advisory: Cisco IPSec Malformed IKE Packet Vulnerability

Revision 2.0

Last Updated 2005 March 30 at 1600 UTC (GMT)

For Public Release 2004 April 8 at 1600 UTC (GMT)

- - -----------------------------------------------------------------------


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

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A malformed Internet Key Exchange (IKE) packet may cause the Cisco
Catalyst 6500 Series Switch or the Cisco 7600 Series Internet Router to
reload. Only devices running Cisco IOS software with Crypto support are

This vulnerability is documented as Cisco bug ID CSCed30113. There are
workarounds available to mitigate the effects of this vulnerability.

Cisco has made free software available to address this vulnerability
for all affected customers.

The title of this advisory has been updated from "Cisco IPSec VPN
Services Module Malformed IKE Packet Vulnerability" to the current
title due to a change in the products affected no longer being limited
to those devices with a VPN Services Module installed.

This advisory will be posted at

Affected Products

Vulnerable Products

The vulnerability is only present if a Crypto feature set is being
used. Customers can verify if they are running a Crypto feature set via
the show version command:

    Router#show version
    Cisco Internetwork Operating System Software 
    IOS (tm) c6sup2_rp Software (c6sup2_rp-PK9S-M), Version 12.2(18)SXD3, RELEASE SOFTWARE (fc1)
    Technical Support: http://www.cisco.com/techsupport
    Copyright (c) 1986-2004 by cisco Systems, Inc.
    Compiled Thu 09-Dec-04 19:35 by pwade
    Image text-base: 0x4002100C, data-base: 0x422E8000

Software that contains the 'K9' designation, as in the following line,
includes the Crypto feature set:

    IOS (tm) c6sup2_rp Software (c6sup2_rp-PK9S-M), Version 12.2(18)SXD3, RELEASE SOFTWARE (fc1)

All Cisco Catalyst 6500 Series Switch and the Cisco 7600 Series
Internet Router hardware running the following Cisco IOS releases are
affected by this vulnerability.

|  Release   |     Affected Releases     |
|   Train    |                           |
| 12.2SXA    | earlier than 12.2(17b)SXA |
| 12.2SXB    | earlier than 12.2(17d)SXB |
| 12.2SX     | 12.2(17a)SX through 12.2  |
|            | (17a)SX4                  |
| 12.2SY     | earlier than 12.2(14)SY3  |

Products Confirmed Not Vulnerable

Cisco Catalyst 6500 Series Switches and Cisco 7600 Series Internet
Routers running Cisco IOS release train 12.1E are not affected by this

To determine your software revision, type show version at the command
line prompt.

No other Cisco products are currently known to be affected by this


A malformed IKE packet may cause an affected device to reload.

This vulnerability could be used to conduct a Denial of Service (DoS)
attack against a vulnerable device. This vulnerability is known to only
exist in the modified IKE code which was incorporated in the 12.2SXA,
12.2SXB, 12.2SX and 12.2SY Cisco IOS software release trains.

Cisco IOS devices with Crypto support will process IKE messages by
default. More information can be found here:

The Internetworking Terms and Cisco Systems Acronyms online guides can
be found at http://www.cisco.com/univercd/cc/td/doc/cisintwk/.

This vulnerability is documented in the Cisco Bug Toolkit as Bug ID 


Successful exploitation of this vulnerability could result in a reload
of the device. Repeated exploitation could result in a sustained DoS

Software Versions and Fixes

This vulnerability has been fixed in the following Cisco IOS releases
for the Cisco Catalyst 6500 Series Switch and the Cisco 7600 Series
Internet Router hardware:

|  Release   |      Fixed Releases       |
|   Train    |                           |
| 12.2SXA    | 12.2(17b)SXA and later    |
| 12.2SXB    | 12.2(17d)SXB and later    |
| 12.2SX     | Migrate to 12.2(17d)SXB   |
|            | or later                  |
| 12.2SY     | 12.2(14)SY3 and later     |

Please refer to these documents for more information:

  * 12.2(17b)SXA Release Notes:
  * 12.2(17d)SXB Release Notes:
  * 12.2(14)SY3 Release Notes:

When considering software upgrades, please also consult
http://www.cisco.com/warp/public/707/advisory.html 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") for assistance.

Obtaining Fixed Software

Cisco is offering free software upgrades to address this vulnerability
for all affected customers.

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/tacpage/library/12.2/index.shtml.

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 assistance with the upgrade,
which should be free of charge.

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

Please 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.

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

See 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.

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


The effectiveness of any workaround 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 is the most
appropriate for use in the intended network before it is deployed.

Customers that do not require IPSec functionality on their devices can
use the command 'no crypto isakmp enable' in configuration mode to
disable processing of IPSec and eliminate their exposure.

As a possible mitigation, access-lists could be applied on the affected
IOS platforms to limit the source IP addresses permitted to establish
IPSec sessions to the device.

Exploitation and Public Announcements

The Cisco PSIRT is not aware of any public announcements or malicious
use of the vulnerability described in this advisory.

This vulnerability was reported to Cisco PSIRT by a customer.

Status of This Notice: FINAL

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

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


This advisory will be posted on Cisco's worldwide website at

In addition to worldwide web posting, a text version of this notice is
clear-signed with the Cisco PSIRT PGP key having the fingerprint 8C82
5207 0CA9 ED40 1DD2 EE2A 7B31 A8CF 32B6 B590 and is posted to the
following e-mail and Usenet news recipients.

  * cust-security-announce@cisco.com
  * first-teams@first.org (includes CERT/CC)
  * bugtraq@securityfocus.com
  * vulnwatch@vulnwatch.org
  * cisco@spot.colorado.edu
  * cisco-nsp@puck.nether.net
  * full-disclosure@lists.netsys.com
  * comp.dcom.sys.cisco@newsgate.cisco.com
  * Various internal Cisco mailing lists

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

Revision History

|          |                | Updated the |
|          |                | advisory to |
|          |                | reflect     |
|          |                | devices     |
|          |                | without the |
|          |                | VPNSM may   |
|          |                | be          |
|          |                | affected.   |
|          |                | Added 12.2  |
|          |                | (17d)SX as  |
| Revision | 2005-March-30  | an affected |
| 2.0      |                | release     |
|          |                | train.      |
|          |                | Added       |
|          |                | information |
|          |                | for         |
|          |                | determining |
|          |                | the         |
|          |                | presence of |
|          |                | the crypto  |
|          |                | feature     |
|          |                | set.        |
|          |                | Updated the |
|          |                | 12.2(14)    |
|          |                | SY03        |
|          |                | Release     |
| Revision | 2005-January-4 | Notes URL   |
| 1.2      |                | in the      |
|          |                | Software    |
|          |                | Fixes and   |
|          |                | Versions    |
|          |                | section.    |
|          |                | Removed     |
|          |                | 12.2ZA as a |
| Revision |                | vulnerable  |
| 1.1      | 2004-April-8   | Cisco IOS   |
|          |                | software    |
|          |                | release     |
|          |                | train.      |
| Revision |                | Initial     |
| 1.0      | 2004-April-8   | 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 website at
This includes instructions for press inquiries regarding Cisco
security notices. All Cisco security advisories are available at

Version: GnuPG v1.4.0 (SunOS)


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