[c-nsp] Cisco Security Advisory: Cisco Clean Access Unauthenticated API Access

Wed Aug 17 12:00:00 EDT 2005

Cisco Clean Access (CCA) is a software solution that can automatically detect,
isolate, and clean infected or vulnerable devices that attempt to access your
network.

CCA includes as part of the architecture an Application Program Interface
(API). Lack of authentication while invoking API methods can allow an attacker
to bypass security posture checking, change the assigned role for a user,
disconnect users and can also lead to information disclosure on configured
users.

Cisco has made free software patches available to address this vulnerability.

This advisory is posted at
http://www.cisco.com/warp/public/707/cisco-sa-20050817-cca.shtml .

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

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

  * CCA releases 3.3.0 to 3.3.9
  * CCA releases 3.4.0 to 3.4.5
  * CCA releases 3.5.0 to 3.5.3

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

The following products are confirmed not vulnerable:

  * Any CCA release previous to 3.3.0
  * CCA release 3.5.4 or later

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

Details
=======

The CCA solution comprises three main components:

  * One or more CCA Servers
  * A CCA Manager
  * Optional CCA Agents

Customers configure the solution using a Web-based interface on the CCA Manager
and the CCA Manager distributes that configuration to the CCA Servers.

As part of the solution, the CCA Manager offers a documented way to access the
CCA Manager API using the Hypertext Transfer Protocol (HTTP) over TLS (HTTPS)
protocol. The API provides methods to allow customer-written scripts to do the
following:

  * Modify the list of clean machines
  * Change user roles
  * Get user information
  * Query a given user login time
  * Modify timeout values for established user sessions
  * Perform some additional functions

A complete list of methods that can be invoked in this way can be found in the
CCA Manager Installation and Administration Guide, page 13-21, available at 
http://www.cisco.com/en/US/products/ps6128/products_user_guide_list.html

An attacker with access to the network where the CCA Manager is located can use
a custom script to invoke the API without being required to provide
authentication credentials.

This vulnerability is documented in the Cisco Bug Toolkit as Bug ID CSCsb48572
(registered customers only)

Impact
======

Successful exploitation of the vulnerability may result in one or more of the
following:

  * Machines being added to the CCA clean list, bypassing CCA checks and being
    allowed access to the network regardless of their state
  * Machines being removed from the CCA clean list, preventing those machines
    from accessing the network
  * Users being assigned to different roles than those configured by the CCA
    administrator, possibly granting access to parts of the network that they
    should not been allowed to access
  * Information disclosure - by using the API to query the CCA Manager an
    attacker could collect user names and properties of users configured in the
    CCA Manager

Software Versions and Fixes
===========================

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.

Cisco has developed a software fix for this vulnerability for all affected
versions. Once the fix is applied to a CCA Manager running an affected release,
any attempt to access the API by a custom script will be authenticated against
the user database.

In order to get the fix, customers should access the CCA software patches
download page. The fix consists of two files:

  * Patch-CSCsb48572.tar.gz - this file contains the fix for all affected
    software versions. It will determine at runtime the CCA software version in
    use and apply the appropriate fix.
  * Readme-Patch-CSCsb48572.txt - this file contains instructions on how to
    apply the fix to a vulnerable CCA Manager server.

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

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 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 at 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 at cisco.com" or "security-alert at 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
http://www.cisco.com/public/sw-center/sw-usingswc.shtml .

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.

No specific workaround has been identified for this vulnerability. However,
this vulnerability can be mitigated by restricting access to the CCA Manager to
known, trusted IP addresses. A sample access-list would be as follows:

    access-list 101 permit tcp <management network address> \
		<management network mask> host <CCA Manager server address> eq 443
    access-list 101 permit tcp host <management host> \
		host <CCA Manager server address> eq 443
    access-list 101 deny tcp any host <CCA Manager server address> eq 443
    access-list 101 permit ip any any 

    interface type/number
       ip access-group 101 in

Refer to the SAFE Security Blueprint for Enterprise Networks (available at 
http://www.cisco.com/go/safe) for additional information about how to secure
your network management infrastructure.

Exploitation and Public Announcements
=====================================

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

Cisco would like to thank Troy Holder from the North Carolina State University
for bringing this to our attention.

Status of This Notice: FINAL
============================

THIS ADVISORY IS PROVIDED ON AN "AS IS" BASIS AND DOES NOT IMPLY ANY KIND OF
GUARANTEE OR WARRANTY, INCLUDING THE WARRANTY OF MERCHANTABILITY. YOUR USE OF
THE INFORMATION ON THE ADVISORY OR MATERIALS LINKED FROM THE ADVISORY IS AT
YOUR OWN RISK. CISCO RESERVES THE RIGHT TO CHANGE OR UPDATE THIS NOTICE AT ANY
TIME.

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.

Distribution
============

This advisory is posted on Cisco's worldwide website at
http://www.cisco.com/warp/public/707/cisco-sa-20050817-cca.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 at cisco.com
  * first-teams at first.org (includes CERT/CC)
  * bugtraq at securityfocus.com
  * vulnwatch at vulnwatch.org
  * cisco at spot.colorado.edu
  * cisco-nsp at puck.nether.net
  * full-disclosure at lists.grok.org.uk
  * comp.dcom.sys.cisco at 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   | 2005-August-17 | Initial       |
| 1.0        |                | 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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