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Cisco Security Advisory: Cisco Network Access Control Guest Server
System Software Authentication Bypass Vulnerability

Advisory ID: cisco-sa-20110330-nac

Revison 1.0

For Public Release 2011 March 30 1600 UTC (GMT)
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Summary
=======

Cisco Network Access Control (NAC) Guest Server system software
contains a vulnerability in the RADIUS authentication software that
may allow an unauthenticated user to access the protected network.

Cisco has released free software updates that address this
vulnerability.

This advisory is posted at:
http://www.cisco.com/warp/public/707/cisco-sa-20110330-nac.shtml

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

Cisco NAC Guest Server provides guest policy enforcement to Cisco NAC
appliances and Cisco Wireless LAN Controllers, where guest policies
are enforced.

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

This vulnerability affects all versions of NAC Guest Server software
prior to software version 2.0.3. The software version is displayed on
the login page of the web server.

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

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

Details
=======

The Cisco NAC Guest Server system software contains a vulnerability
in the configuration file of the RADIUS authentication software. This
misconfiguration may allow an unauthenticated user to access the
protected network. This vulnerability may result in authentication
bypass without requiring a valid username or password.

This vulnerability is documented in Cisco Bug ID CSCtj66922 (
registered customers only) and has been assigned Common
Vulnerabilities and Exposures (CVE) ID CVE-2011-0963.

Vulnerability Scoring Details
+----------------------------

Cisco has provided scores for the vulnerability 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

* CSCtj66922 -  Authentication Bypass Vulnerability

CVSS Base Score - 5.0
    Access Vector -            Network
    Access Complexity -        Low
    Authentication -           None
    Confidentiality Impact -   Partial
    Integrity Impact -         None
    Availability Impact -      None

CVSS Temporal Score - 4.1
    Exploitability -           Functional
    Remediation Level -        Official-Fix
    Report Confidence -        Confirmed

Impact
======

Successful exploitation of the vulnerability may allow unauthorized
users to access the protected network.

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.

Software versions prior to 2.0.3 are affected by this vulnerability.
Fixed software and workarounds are available for all NAC Guest Server
devices.

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

It is possible to modify the RADIUS configuration file of the Cisco
NAC Guest Access Server to eliminate thepotential for authentication
bypass. The following commands modify the RADIUS configuration line
file and restart the RADIUS daemon to read the new configuration
file.

The configuration file may be modified by running the following
command from the command-line interface (CLI) of the device:

    # cp /etc/raddb/radiusd.conf /etc/raddb/radiusd.conf.orig
    # sed -i 's/php -f/php/g' /etc/raddb/radiusd.conf
    # service radiusd restart

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

Cisco has released free software updates that address this
vulnerability. 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/docs/general/warranty/English/EU1KEN_.html
or as otherwise set forth at Cisco.com Downloads at:
http://www.cisco.com/public/sw-center/sw-usingswc.shtml

The latest version of Cisco NAC Guest Access Server system software
may be obtained at:
http://www.cisco.com/cisco/software/release.html?mdfid=282450822&flowid=4363&softwareid=282562545

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/en/US/support/tsd_cisco_worldwide_contacts.html 
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.

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-20110330-nac.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-bulletins@lists.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
================

+---------------------------------------+
| Revision |               | Initial    |
| 1.0      | 2011-March-30 | 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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Copyright 2010-2011 Cisco Systems, Inc. All rights reserved.
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