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Cisco Security Advisory

Cisco IPSec Malformed IKE Packet Vulnerability

Advisory ID: cisco-sa-20040408-vpnsm

http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20040408-vpnsm

Revision 2.0

For Public Release 2004 April 8 16:00  UTC (GMT)


Summary

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 affected.

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 http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20040408-vpnsm.

Affected Products

This section provides details on 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 Train

Affected Releases

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 vulnerability.

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 vulnerability.

Details

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: http://www.cisco.com/en/US/docs/ios/12_3/security/command/reference/sec_c2g.html

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 CSCed30113 ( registered customers only) .

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

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

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 Train

Fixed Releases

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:

When considering software upgrades, please also consult http://www.cisco.com/en/US/products/products_security_advisories_listing.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.


Workarounds

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.

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/en/US/support/tsd_cisco_worldwide_contacts.html 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 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 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 advisory will be posted on Cisco's worldwide website at http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20040408-vpnsm.

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

Revision 2.0

2005-March-30

Updated the advisory to reflect devices without the VPNSM may be affected. Added 12.2(17d)SX as an affected release train. Added information for determining the presence of the crypto feature set.

Revision 1.2

2005-January-4

Updated the 12.2(14)SY03 Release Notes URL in the Software Fixes and Versions section.

Revision 1.1

2004-April-8

Removed 12.2ZA as a vulnerable Cisco IOS software release train.

Revision 1.0

2004-April-8

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 website 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.


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