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UNIRAS Brief - 269/06 - Cisco Security Advisory: cisco-sa-20060405-css - Cisco 11500 Content Services Switch



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   UNIRAS (UK Govt CERT) Briefing Notice - 269/06 dated 06.04.06  Time: 13:25  
  UNIRAS is part of NISCC (National Infrastructure Security Co-ordination Centre)
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  UNIRAS material is also available from its website at www.uniras.gov.uk and
         Information about NISCC is available from www.niscc.gov.uk
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Title
=====

Cisco Security Advisory: cisco-sa-20060405-css - Cisco 11500 Content Services Switch 
HTTP Request Vulnerability

Detail
====== 

Cisco CSS 11500 Series Content Services Switches configured for Hyper
Text Transfer Protocol (HTTP) compression are vulnerable to a Denial
of Service (DoS) attack when processing valid, but obsolete, or
specially crafted HTTP request.


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Cisco Security Advisory: Cisco 11500 Content Services Switch HTTP
Request Vulnerability

Advisory ID: cisco-sa-20060405-css

http://www.cisco.com/warp/public/707/cisco-sa-20060405-css.shtml

Revision 1.0

For Public Release 2006 April 05 1500 GMT (UTC)

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Contents
========

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

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Summary
=======

Cisco CSS 11500 Series Content Services Switches configured for Hyper
Text Transfer Protocol (HTTP) compression are vulnerable to a Denial
of Service (DoS) attack when processing valid, but obsolete, or
specially crafted HTTP request.

Cisco has made free software available to address this vulnerability
for affected customers. The workaround is to disable HTTP
compression.

This advisory is posted at 
http://www.cisco.com/warp/public/707/cisco-sa-20060405-css.shtml.

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

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

Cisco CSS 11500 Series Content Services Switches that are configured
for HTTP compression are vulnerable.

A Cisco CSS11500 that is configured for HTTP compression will have
configuration similar to the following, which can be seen by issuing
the show running-config command:

    service compression_service_name
            ....
            ....
            compress enable
            ....
            ....


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

Cisco CSS 11500 Series Content Services Switches that are not
configured for HTTP compression are not vulnerable.

No other Cisco products are currently known to be affected by these
vulnerabilities.

Details
=======

The Cisco CSS 11500 Content Service Switch is load balancing device
designed to provide robust, scalable network services (Layer 4-7) for
data centers. The Cisco CSS 11500 performs an analysis of protocol
headers and directs requests to an appropriate resource based on
configurable policies. With a compression module, a Cisco CSS 11500
can compress HTTP client traffic.

For more information about HTTP compression on CSS 11500 switches,
refer to the following URL:

http://www.cisco.com/en/US/products/hw/contnetw/ps792/products_configuration_guide_chapter09186a0080579fef.html

A Cisco CSS 11500 enabled for HTTP compression may reload after
receiving valid, but obsolete, or specially crafted HTTP request.

Cisco CSS 11500 switches where HTTP compression is not used or is
disabled are not affected by this vulnerability.

The vulnerability is documented in the following Cisco Bug ID:

  * CSCek24160 ( registered customers only) CSS cores while using
    software compression.

Impact
======

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

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 issue is fixed in version 8.10.1.6 of CSS software. Fixed
software can be downloaded from the following URL::

http://www.cisco.com/cgi-bin/tablebuild.pl/css11500-maint?psrtdcat20e2

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

The workaround is to disable HTTP compression. That can be
accomplished using the compress disable command.

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@xxxxxxxxx" or "security-alert@xxxxxxxxx"
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@xxxxxxxxx

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/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.

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 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 is posted on Cisco's worldwide website at 
http://www.cisco.com/warp/public/707/cisco-sa-20060405-css.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@xxxxxxxxx
  * first-teams@xxxxxxxxx
  * bugtraq@xxxxxxxxxxxxxxxxx
  * vulnwatch@xxxxxxxxxxxxx
  * cisco@xxxxxxxxxxxxxxxxx
  * cisco-nsp@xxxxxxxxxxxxxxx
  * full-disclosure@xxxxxxxxxxxxxxxxx
  * comp.dcom.sys.cisco@xxxxxxxxxxxxxxxxxx

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 |               | Initial    |
| 1.0      | 2006-April-05 | 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/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.

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UNIRAS wishes to acknowledge the contributions of Cisco for the information 
contained in this Briefing. 
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This Briefing contains the information released by the original author. Some 
of the information may have changed since it was released. If the vulnerability 
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 
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and opinions of authors expressed within this notice shall not be used for 
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not be liable for any loss or damage whatsoever, arising from or in connection 
with the usage of information contained within this notice.

UNIRAS is a member of the Forum of Incident Response and Security Teams (FIRST) 
and has contacts with other international Incident Response Teams (IRTs) in 
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rapid reaction to incidents, and to promote information sharing amongst its 
members and the community at large. 
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<End of UNIRAS Briefing>

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