AUSCERT External Security Bulletin Redistribution

                  ESB-2002.160 -- Cisco Security Advisory
             Web interface vulnerabilities in ACS for Windows
                               4 April 2002


        AusCERT Security Bulletin Summary

Product:                Cisco Secure Access Control Server 2.6.X
                        Cisco Secure Access Control Server 3.0.1
Vendor:                 Cisco
Operating System:       Windows
Impact:                 Denial of Service
                        Execute Arbitrary Code/Commands
                        Access Privileged Data
Access Required:        Remote

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Cisco Security Advisory: Web interface vulnerabilities in ACS for Windows

Revision 1.0

For Public Release 2002 April 03 16:00 (UTC +0000)

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    Products Affected
    Software Versions and Fixes
    Obtaining Fixed Software
    Exploitation and Public Announcements
    Status of This Notice
    Revision History
    Cisco Security Procedures

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Cisco Secure Access Control Server (ACS) for Windows contains two
vulnerabilities. One vulnerability can lead to the execution of an
arbitrary code on an ACS server and the second can lead to an unauthorized
disclosure of information. The patch is available for both vulnerabilities.

Cisco Secure ACS for Unix is not vulnerable. No other Cisco product is

There is no direct workaround for the vulnerabilities but it is possible to
mitigate them to a great extent. See the Workarounds section for details.

This advisory is available at the 

Products Affected
The affected product is Cisco Secure Access Control Server for Windows
releases 2.6.x and ACS 3.0.1 (build 40). A patche is available.

Cisco Secure ACS for Unix is not affected.

No other Cisco products are affected.

There are two different vulnerabilities, as described by the Bug IDs below.
The first can lead to execution of an arbitrary code and the second can be
used to reveal customer data.

  * By connecting to a port 2002 and sending a crafted URL it is possible
    to, in a less severe case, kill the CSADMIN module or, in a severe
    case, to execute an arbitrary user supplied code. The functionality of
    authentication, authorization, and accounting (AAA) is not affected by
    termination of the CSADMIN module. This means that users will be able
    to authenticate normally. Only the administration function will be
    affected. Port 2002 is used by the CSADMIN module for remote
    By providing an URL containing formatting symbols (for example, %s, %p)
    it is possible to execute an user provided code. This technique is
    described in the following article: 
    This vulnerability is documented as Cisco Bug IDs CSCdx17622 and 
  * The another vulnerability can lead to unauthorized disclosure of data.
    By using "...." in the URL it is possible to access data in any
    directory outside the Web root directory but on the same hard disk or
    disk partition. With this technique it is possible to access only the
    following file types: html, htm, class, jpg, jpeg or gif.
    Please note that an attacker must know the exact location and file
    name. It is not possible to browse a directory this way.
    This vulnerability is documented as Cisco Bug IDs CSCdx17689 and 

By exploiting the format vulnerability an attacker may execute the
arbitrary code on the machine. This code will be executed in the same
context as the CSADMIN process, and that is Administrator. Executing
arbitrary code will lead to a total compromise of the machine.

By exploiting the directory traversal vulnerability an attacker can gain an
unauthorized access to information in on of the following file types: html,
htm, class, jpg, jpeg or gif. The main issue may be html files with
hardcoded passwords or other sensitive information.

Software Versions and Fixes
Both vulnerabilities are fixed by the patched CSAdmin.exe file available
at: http://www.cisco.com/cgi-bin/tablebuild.pl/cs-acs-win . The file names
are: CSAdmin-patch-2.6-4-4.zip and CSAdmin-patch-3.0-1-40.zip.

In order to install the patches, follow this procedure below while logged
in as Administrartor:

 1. Manually stop the CSAdmin Service
 2. Rename the /CSAdmin/CSAdmin.exe file
 3. Copy the patched CSAdmin.exe to /CSAdmin
 4. Manually start the CSAdmin Service

Obtaining Fixed Software
Cisco is offering free software patch to address this vulnerability for all
affected customers. Customers may only install and expect support for the
feature sets they have purchased.

Customers with service contracts should contact their regular update
channels to obtain any software release containing the feature sets they
have purchased. For most customers with service contracts, this means that
upgrades should be obtained through the Software Center on Cisco's
Worldwide Web site at http://www.cisco.com.

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.

Customers who purchased directly 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 obtain fixed software by contacting the Cisco Technical
Assistance Center (TAC). In these cases, customers may only upgrade to a
later version of the same release.

Cisco 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

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.

Please have your product serial number available and give the URL of this
notice as evidence of your entitlement to a free upgrade.

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

There are no direct workarounds for these vulnerabilities. However, by
exercising the standard best practices it is possible to significantly
mitigate both issues. These practices are:

  * Block all unnecessary traffic on the outer network edge. This includes
    private IP address space (, for example) and spoofed packets.
    This can be accomplished using routers or firewalls. For instruction on
    how to accomplish this with Cisco routers, please consult documents at 
  * Separate critical internal infrastructure from the rest of your
    internal network.

We strongly recommend that these practices are also followed when deploying
Cisco ACS for Unix, even though it is not vulnerable to the mentioned

Exploitation and Public Announcements
Both vulnerabilities were reported by Jonas Ländin and Patrik Karlsson from
iXsecurity. Cisco PSIRT was made aware that an exploit program for the
format vulnerability exist. This exploit is thought not to be released to
the general public.

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 http://
www.cisco.com/warp/public/707/ACS-Win-Web.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

  * 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 1.0|2002-April-03 16:00 UTC+0000|Initial 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
Web site at http://www.cisco.com/warp/public/707/sec_incident_response.shtml
This includes instructions for press inquiries regarding Cisco security 

All Cisco Security Advisories are available at 
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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.
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