Search:

June 2008

3645 - Cisco Intrusion Prevention System Jumbo Frame Denial of Service

ID: 3645
Date: 20/06/2008

Title: 3645 - Cisco Intrusion Prevention System Jumbo Frame Denial of Service
Platform level affected:Security Software
Hardware components affected:Network Router/Switch/Modem
Specific operating systems components affected: Other
Net-enabled software: Other
Security software:Firewall
Other software: Other
Remediation Summary:Update your copy of the software with the download available from the supplier.
Vendors affected:Cisco
Applications affected:Cisco Intrusion Prevention System
Adversity source: Unknown
Attack Vector: Vulnerability exploitation
Virulence: Unknown
Warning Status: Unknown
Potential Damage: Network DOS
Possible Duration: Unknown
Availability of fix: Available
Type of fix: Patch
Source: Cisco
Reliability of source: Trusted
Source URL: http://www.cisco.com/warp/public/707/cisco-sa-20080618-ips.shtml
Abstract: Description of a vulnerability in Cisco Intrusion Prevention System (IPS) platforms that have gigabit network interfaces installed.

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

Cisco Security Advisory: Cisco Intrusion Prevention System Jumbo
Frame Denial of Service

Advisory ID: cisco-sa-20080618-ips

Revision 1.0

For Public Release 2008 June 18 1600 UTC (GMT)

+---------------------------------------------------------------------

Summary
=======

Cisco Intrusion Prevention System (IPS) platforms that have gigabit network interfaces installed and are deployed in inline mode contain a denial of service vulnerability in the handling of jumbo Ethernet frames. This vulnerability may lead to a kernel panic that requires a power cycle to recover platform operation. Platforms deployed in promiscuous mode only or that do not contain gigabit network interfaces are not vulnerable.

Cisco has released free software updates that address this vulnerability. There is a workaround for this vulnerability.

This advisory is posted at
http://www.cisco.com/warp/public/707/cisco-sa-20080618-ips.shtml.

Affected Products
=================

Vulnerable Products
+------------------

The following Cisco IPS versions are affected:

* Cisco Intrusion Prevention System version 5.x prior to 5.1(8)E2
* Cisco Intrusion Prevention System version 6.x prior to 6.0(5)E2

The following Cisco IPS platforms ship with gigabit network interfaces and are vulnerable if they are deployed in inline mode:

* 4235
* 4240
* 4250
* 4250SX *
* 4250TX
* 4250XL *
* 4255
* 4260
* 4270

* The 4250SX and 4250XL models ship with gigabit network interfaces that are normally used for remote administration and monitoring. If the gigabit network interfaces are configured for use with inline mode, the platform is vulnerable.

To determine the version of software that is running on a Cisco IPS platform, log into the platform using the console or Secure Shell
(SSH) and issue the show version command.

    sensor# show version
    Application Partition:

    Cisco Intrusion Prevention System, Version 6.0(4a)E1

To determine whether a Cisco IPS platform has interfaces configured for inline mode, log into the platform using the console or SSH and issue the show interfaces command. Look for paired interfaces in the Inline Mode statement of the command output.

    sensor# show interfaces
    ...
    MAC statistics from interface GigabitEthernet0/1
       Interface function = Sensing interface
       Description =
       Media Type = TX
       Missed Packet Percentage = 0
       Inline Mode = Paired with interface GigabitEthernet0/0
    ...
    MAC statistics from interface GigabitEthernet0/0
       Interface function = Sensing interface
       Description =
       Media Type = TX
       Missed Packet Percentage = 0
       Inline Mode = Paired with interface GigabitEthernet0/1

Products Confirmed Not Vulnerable
+--------------------------------

The following Cisco IPS platforms are not vulnerable:

* 4210
* 4215
* SSM-AIP10
* SSM-AIP20
* SSM-AIP40
* AIM-IPS
* NM-CIDS
* IDSM2

Cisco IPS version 6.1(1) is not vulnerable. Cisco IOS with the Intrusion Prevention System feature is not vulnerable. No other Cisco products are currently known to be affected by this vulnerability.

Details
=======

Certain Cisco IPS platforms contain a denial of service vulnerability in the handling of jumbo ethernet frames. When a specific series of jumbo Ethernet frames is received on a gigabit network interface of a vulnerable Cisco IPS platform that is deployed in inline mode, a kernel panic may occur that results in the complete failure of the platform and causes a network denial of service condition. Cisco IPS platforms that are deployed in promiscuous mode only or that do not contain gigabit network interfaces are not vulnerable.

Jumbo Ethernet support is usually deployed in data center environments to increase inter-server communication performance and is not a default configuration for Cisco routers and switches.
Support for jumbo Ethernet frames must be enabled on each device that require the feature. In order to exploit this vulnerability, an attacker must be able to inject jumbo Ethernet frames to a vulnerable Cisco IPS platform that is deployed in inline mode.

If they are configured to use bypass mode to allow traffic to pass in the event of a system failure, all Cisco IPS platforms will fail to forward traffic except for the 4260 and 4270 platforms. The Cisco IPS 4260 and 4270 platforms contain a hardware bypass feature that allows them to pass network traffic in the event of a kernel panic or power outage. They will pass traffic by default if the hardware bypass feature is engaged.

This vulnerability is documented in Cisco Bug ID CSCso64762 and has been assigned Common Vulnerabilities and Exposures (CVE) ID CVE-2008-2060.

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

CSCso64762 - IPS Jumbo frame not processed properly

CVSS Base Score - 7.8
    Access Vector - Network
    Access Complexity - Medium
    Authentication - None
    Confidentiality Impact - Partial
    Integrity Impact - None
    Availability Impact - Complete

CVSS Temporal Score - 6.4
    Exploitability - Functional
    Remediation Level - Official Fix
    Report Confidence - Confirmed

Impact
======

Successful exploitation of the vulnerability may result in a network denial of service condition. A power cycle is required to recover operation. An attacker may be able to evade access controls and detection of malicious activity in the case of Cisco IPS 4260/4270 platforms that have hardware bypass configured to pass traffic in the event of a kernel panic.

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.

This vulnerability is fixed in Cisco IPS versions 5.1(8)E2 and 6.0(5)
E2 that are expected to be available for download by June 20, 2008.

Fixed software Cisco IPS version 5.1(8)E2 will be available at the following link:

http://www.cisco.com/pcgi-bin/tablebuild.pl/ips5?psrtdcat20e2

Fixed software Cisco IPS version 6.0(5)E2 will be available at the following link:

http://www.cisco.com/pcgi-bin/tablebuild.pl/ips6?psrtdcat20e2

Workarounds
===========

To workaround this vulnerability, administrators can disable jumbo Ethernet support on routers and switches directly that are connected to vulnerable Cisco IPS platforms. This workaround may produce a negative performance impact in certain environments. Administrators are encouraged to upgrade to fixed software.

For more information about configuring Jumbo frames on Cisco switches, please reference the following link:

http://www.cisco.com/en/US/products/hw/switches/ps700/products_configuration_example09186a008010edab.shtml

Obtaining Fixed Software
========================

Cisco has released free software updates that address these vulnerabilities. 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/en/US/products/prod_warranties_item09186a008088e31f.html,
or as otherwise set forth at Cisco.com Downloads at http://www.cisco.com/public/sw-center/sw-usingswc.shtml.

Do not contact 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 agreements 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 do not hold a Cisco service contract, and customers who purchase through third-party vendors but are unsuccessful in obtaining fixed software through their point of sale should acquire 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

Customers should have their product serial number available and be prepared to give the URL of this notice as evidence of 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 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 by HD Moore of BreakingPoint Systems.

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 is posted on Cisco's worldwide website at:

http://www.cisco.com/warp/public/707/cisco-sa-20080618-ips.shtml

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
* first-teams@first.org
* bugtraq@securityfocus.com
* vulnwatch@vulnwatch.org
* cisco@spot.colorado.edu
* cisco-nsp@puck.nether.net
* full-disclosure@lists.grok.org.uk
* comp.dcom.sys.cisco@newsgate.cisco.com

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
================

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/en/US/products/products_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.
-----BEGIN PGP SIGNATURE-----

iD8DBQFIWTYs86n/Gc8U/uARAn3FAKCIkVy8TfwwoKE3pFjMfRMyZN4+SACghKEB
Vb2Ngh4ALQrSRsWdWiy/2u4=
=IvlU
-----END PGP SIGNATURE-----

This advisory contains information released by the original author. Some of the information may have changed since it was released. If the issue affects you, it may be prudent to retrieve the advisory from the site of the original source to ensure that you receive the most current information concerning that problem. Reference to any specific commercial product, process, or service by trade name, trademark manufacturer, or otherwise, does not constitute or imply its endorsement, recommendation, or favouring by CPNI.

The views and opinions of authors expressed within this notice shall not be used for advertising or product endorsement purposes. CPNI shall not accept responsibility for any errors or omissions contained within this advisory. In particular, they shall not be liable for any loss or damage whatsoever, arising from or in connection with the usage of information contained within this advisory.

CSIRTUK is a member of the Forum of Incident Response and Security Teams (FIRST) and has contacts with other international Incident Response Teams (IRTs) in order to foster cooperation and coordination in incident prevention, to prompt rapid reaction to incidents, and to promote information sharing amongst its members and the community at large.