AUSCERT External Security Bulletin Redistribution

                  ESB-2002.062 -- Cisco Security Advisory
         Cisco Secure Access Control Server Novell Directory Service 
             Expired/Disabled User Authentication Vulnerability
                              8 February 2002


        AusCERT Security Bulletin Summary

Product:                Cisco Secure Access Control Server version 3.0.1 
                        (configured for Novell Directory Services)
Vendor:                 Cisco Systems
Operating System:       Windows NT server
Impact:                 Increased Privileges
Access Required:        Existing Account

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Cisco Security Advisory:  Cisco Secure Access Control Server Novell
Directory Service Expired/Disabled User Authentication Vulnerability

Revision 1.0

For Public Release 2002 February 07 08:00 (UTC -0800)



Specific versions of Cisco Secure Authentication Control Server (ACS)
allows authentication of users that have been explicitly disabled or
expired in the Novell Directory Services (NDS).  There is a software patch
that may be applied, and software upgrades will also address this problem.

The complete notice will be available at

Affected Products

Only Cisco Secure ACS version 3.0.1, configured for NDS, is affected.

No other Cisco products are affected by this vulnerability.

The following are NOT affected by this vulnerability:

   * Systems with Cisco Secure ACS for Windows NT version 2.6 and 2.5 and
   * Cisco Secure ACS version 3.0.1 that is NOT configured for use with NDS
   * Cisco Secure ACS for UNIX


To determine if your Cisco Secure ACS for Windows NT server is configured
for NDS, please review the "External User Databases/Unknown User Policy" on
the Administration interface.  If the name of your NDS configuration
appears in the "Selected Databases" list, then you are using NDS for
authentication and are affected by this vulnerability if you are running
version 3.0.1.

Users who are marked as "expired" or "disabled" on the NDS database will
still authenticate if their credentials are otherwise correct.  The file
"NDSAuth.DLL" is a module which allows ACS authentication to be handled by
an external NDS server. Versions of this file with the date 2001-Dec-15
ignore the "Disabled" or "Expired" state of these users on NDS.
Authentication attempts by users with a Disabled or Expired status on the
NDS server should be refused, but are permitted due to this vulnerability.

This vulnerability is documented in Cisco Bug ID CSCdw46931.

     DEL/ACS authenticates NDS expired/disabled users.


This vulnerability results in a failure to adequately enforce
authentication criteria, and users that should be prevented from using
services are permitted to authenticate, regardless of their status in the
NDS server.

Software Versions and Fixes

CiscoSecure ACS for Windows NT Server version 3.0.1 is vulnerable and can
be patched.  Future versions of the software will include this patch.
Please review the Workarounds section of this notice for detailed patch
installation instructions.

The patch for this vulnerability can be downloaded from the following
location if you are logged in with a valid CCO user account:
http://www.cisco.com/pcgi-bin/tablebuild.pl/cs-acs-win .

Obtaining Fixed Software

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 Web
site at http://www.cisco.com/pcgi-bin/tablebuild.pl/cs-acs-win .

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 or patch, which should
be free of charge.

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) or by email: tac@cisco.com.

Please give the URL of this notice as evidence of your entitlement to a
software patch. Free software patches for non-contract customers must be
requested through the TAC.

Please do not contact either "psirt@cisco.com" or
"security-alert@cisco.com" for software upgrades or patches.


If you are unable to install the patch, user records that are "disabled" or
"expired" in your NDS database should be temporarily removed until they are
either valid again or the patch has been installed.

Install the patch according to the following directions:

  1. Stop both "CSAUTH" and "CSAdmin" services by entering the following at
     the command prompt:

     net stop CSAuth
     net stop CSAdmin

  2. Locate the <CSNTinstall>/Authenticators directory. For a default
     installation on the C: drive, the location will be the following:
     C:Program FilesCiscoSecure ACS v3.0AuthenticatorsNDSAuth.dll.

    3.  Rename the original NDSAuth.dll to something else (NDSAuth_old.dll,
for example) to save it.

    4.  Replace the original NDSAuth.dll file with the patch file in its

    5. Restart the services by entering the following at the command

     net start CSAuth
     net start CSAdmin

The patch is a single file (ACS30_NDSAuth_patch.zip) and can be downloaded
at the following location if you are logged in with a valid CCO user
account:  http://www.cisco.com/pcgi-bin/tablebuild.pl/cs-acs-win .

Exploitation and Public Announcements

This vulnerability was discovered by internal Quality Assurance.

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 is a final notice. Although Cisco cannot guarantee the accuracy of all
statements in this notice, all of the facts have been checked to the best
of our ability. Cisco does not anticipate issuing updated versions of this
notice unless there is some material change in the facts. Should there be a
significant change in the facts, Cisco may update this notice.

A standalone 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.


This notice will be posted on Cisco's Worldwide Web site at
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
   * bugtraq@securityfocus.com
   * first-teams@first.org (includes CERT/CC)
   * cisco@spot.colorado.edu
   * comp.dcom.sys.cisco
   * firewalls@lists.gnac.com
   * Various internal Cisco mailing lists

Future updates of this notice, if any, will be placed on Cisco's Worldwide
Web server, but may or may not be actively announced on mailing lists or
newsgroups. Users concerned about this problem are encouraged to check the
URL given above for any updates.

Revision History

 Revision     2002-Feb-07 08:00    Initial public release
 Number 1.0   GMT-0800

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
Web site at
http://www.cisco.com/warp/public/707/sec_incident_response.shtml. This
includes instructions for press inquiries regarding Cisco security notices.
All Cisco Security Advisories are available at


This notice is Copyright 2002 by Cisco Systems, Inc. This notice may be
redistributed freely after the release date given at the top of the text,
provided that redistributed copies are complete and unmodified, and include
all date and version information.


Version: PGP 7.0


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