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===========================================================================
             AUSCERT External Security Bulletin Redistribution

                         ESB-2006.0079 -- [Cisco]
         Cisco IOS AAA Command Authorization bypass vulnerability
                              27 January 2006

===========================================================================

        AusCERT Security Bulletin Summary
        ---------------------------------

Product:           Cisco IOS version 12.0T and later devices
Operating System:  Cisco
Impact:            Increased Privileges
Access:            Existing Account

Original Bulletin: 
  http://www.cisco.com/warp/public/707/cisco-response-20060125-aaatcl.shtml

Comment: Only devices with Tcl functionality and the AAA command authorization
         feature are reported vulnerable.

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Cisco Security Notice: Response to AAA Command Authorization by-pass

Document ID: 68840

http://www.cisco.com/warp/public/707/cisco-response-20060125-aaatcl.shtml

Revision 1.0
============

For Public Release 2006 January 25 16:00 UTC (GMT)

+--------------------------------------------------------------------

Contents
========

    Cisco Response
    Additional Information
    Revision History
    Cisco Security Procedures

+--------------------------------------------------------------------

Cisco Response
==============

This is Cisco PSIRT's response to a vulnerability raised direct to
Cisco PSIRT from COLT Telecom.

A vulnerability exists within Cisco Internetwork Operating System
(IOS) Authentication, Authorization, and Accounting (AAA) command
authorization feature, where command authorization checks are not
performed on commands executed from the Tool Command Language 
(Tcl) exec shell. This may allow authenticated users to bypass
command authorization checks in some configurations resulting in
unauthorized privilege escalation.

Devices not running AAA command authorization feature, or do not
support Tcl functionality are not affected by this vulnerability.

We would like to thank Nicolas Fischbach, Senior Manager, Network
Engineering Security of COLT Telecom, for reporting this issue to
Cisco Systems.

We greatly appreciate the opportunity to work with researchers on
security vulnerabilities, and welcome the opportunity to review and
assist in product reports.

Additional Information
======================

Details
+------
Devices that are running AAA command authorization feature and the
IOS has support for the Tcl functionality, may be affected by this 
vulnerability.

A device that has Tcl functionality within IOS, will accept the
command "tclsh" and provide a command-line interface (CLI) prompt 
back with (tcl) in the CLI prompt. 

Example:

    router#tclsh
    router(tcl)#

If the device does not support Tcl functionality, either an error
message or different output will be displayed.

The (tcl) text within the CLI prompt indicates that the user is
within the Tcl Shell mode.

A system configured for AAA command authorization will have a command
line in "show running-configuration" output which is similar to the
following:

aaa authorization commands <privilege-level> <default|list-name>
<group [group-name]> tacacs+ [additional methods]

Example:

aaa authorization commands 15 default group tacacs+ none

Devices impacted by this vulnerability, will allow users to execute
any IOS EXEC command at the users authenticated privilege level from 
within the Tcl shell mode.

This vulnerability is documented in the following bug ID:

  * CSCeh73049 -- tclsh mode bypasses AAA command authorization check

A separate issue, documented below, exists that exacerbates this
vulnerability.  An authenticated user may be placed into Tcl Shell
mode automatically (without the evidence of the (tcl) within the 
router prompt), without any intermediate step of manually entering 
into Tcl Shell mode via the "tclsh" command, only if a previous user 
goes into Tcl Shell mode and terminates the session before leaving 
the Tcl Shell mode.

If a privileged user initiates a Tcl Shell and exits the Tcl Shell
mode without issuing the Tcl Shell command "tclquit" then the Tcl 
Shell process will remain active and attached to the corresponding 
virtual type terminal VTY or teletypewriter  (TTY - line). The next 
authenticated user that accesses the device over the same line will 
have access to the Tcl Shell process, and combined with CSCeh73049
may bypass AAA command authorization checking. This issue is 
documented in the following bug ID:

  * CSCef77770 -- Type ctrl-c or crtl-z causes tclsh prompt to
    disappear

This separate issue is present only in the versions of IOS listed 
below:

  * 12.3T based trains
  * 12.4 based trains
  * 12.2(25)S and onward trains

Vulnerable products
+------------------

  * All Cisco products that are running Cisco IOS and:
    - Have AAA command authorization feature enabled
    - The IOS has support for the Tcl functionality
    - IOS Version 12.0T or later

Products confirmed not Vulnerable
+--------------------------------

  * Products that are not running Cisco IOS are not affected.
  * Products running Cisco IOS versions 12.0 Mainline or earlier are
    not affected.
  * Products running Cisco IOS versions 12.0S are not affected.
  * Products that are running Cisco IOS are not affected unless they
    are configured for AAA command authorization, and support Tcl
    functionality.
  * Products that are running Cisco IOS XR are not affected.

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

Software versions and fixes
+--------------------------

Each row of the Cisco IOS software table below describes a release
train and the platforms or products for which it is intended. If a
given release train is vulnerable, then the earliest possible
releases that contain the fix (the First Fixed Release) and the
anticipated date of availability for each are listed in the Rebuild
and Maintenance columns. A device running a release in the given
train that is earlier than the release in a specific column (less
than the First Fixed Release) is known to be vulnerable. The release
should be upgraded at least to the indicated release or a later
version (greater than or equal to the First Fixed Release label).


+---------------------------------------------------------------+
|      Major Release       | Availability of Repaired Releases  |
|--------------------------+------------------------------------|
| Affected 12.0-Based      | Rebuild       | Maintenance        |
| Release                  |               |                    |
|--------------------------+------------------------------------|
| 12.0T                    | Vulnerable; migrate to 12.2(32) or |
|                          | later                              |
|--------------------------+------------------------------------|
| 12.0XH                   | Vulnerable; migrate to 12.2(32) or |
|                          | later                              |
|--------------------------+------------------------------------|
| 12.0XK                   | Vulnerable; migrate to 12.2(32) or |
|                          | later                              |
|--------------------------+------------------------------------|
| 12.0XL                   | Vulnerable; migrate to 12.2(32) or |
|                          | later                              |
|--------------------------+------------------------------------|
| 12.0XN                   | Vulnerable; migrate to 12.2(32) or |
|                          | later                              |
|--------------------------+------------------------------------|
| 12.0XR                   | Vulnerable; migrate to 12.2(32) or |
|                          | later                              |
|--------------------------+------------------------------------|
| Affected 12.1-Based      | Rebuild       | Maintenance        |
| Release                  |               |                    |
|--------------------------+------------------------------------|
| 12.1                     | Vulnerable; migrate to 12.2(32) or |
|                          | later                              |
|--------------------------+------------------------------------|
| 12.1AA                   | Vulnerable; migrate to 12.2(32) or |
|                          | later                              |
|--------------------------+------------------------------------|
| 12.1E                    | 12.1(26)E5    |                    |
|--------------------------+------------------------------------|
| 12.1EC                   | Vulnerable; migrate to 12.3BC or   |
|                          | later                              |
|--------------------------+------------------------------------|
| 12.1EZ                   | Vulnerable; migrate to 12.1(26)E5  |
|                          | or later                           |
|--------------------------+------------------------------------|
| 12.1GA                   | Vulnerable; migrate to 12.2(32) or |
|                          | later                              |
|--------------------------+------------------------------------|
| 12.1GB                   | Vulnerable; migrate to 12.2(32) or |
|                          | later                              |
|--------------------------+------------------------------------|
| 12.1T                    | Vulnerable; migrate to 12.2(32) or |
|                          | later                              |
|--------------------------+------------------------------------|
| 12.1XA                   | Vulnerable; migrate to 12.2(32) or |
|                          | later                              |
|--------------------------+------------------------------------|
| 12.1XE                   | Vulnerable; migrate to 12.2(32) or |
|                          | later                              |
|--------------------------+------------------------------------|
| 12.1XH                   | Vulnerable; migrate to 12.2(32) or |
|                          | later                              |
|--------------------------+------------------------------------|
| 12.1XI                   | Vulnerable; migrate to 12.2(32) or |
|                          | later                              |
|--------------------------+------------------------------------|
| 12.1XJ                   | Vulnerable; migrate to 12.3(16) or |
|                          | later                              |
|--------------------------+------------------------------------|
| 12.1XL                   | Vulnerable; migrate to 12.3(16) or |
|                          | later                              |
|--------------------------+------------------------------------|
| 12.1XM                   | Vulnerable; migrate to 12.3(16) or |
|                          | later                              |
|--------------------------+------------------------------------|
| 12.1XP                   | Vulnerable; migrate to 12.3(16) or |
|                          | later                              |
|--------------------------+------------------------------------|
| 12.1XQ                   | Vulnerable; migrate to 12.3(16) or |
|                          | later                              |
|--------------------------+------------------------------------|
| 12.1XS                   | Vulnerable; migrate to 12.2(32) or |
|                          | later                              |
|--------------------------+------------------------------------|
| 12.1XT                   | Vulnerable; migrate to 12.3(16) or |
|                          | later                              |
|--------------------------+------------------------------------|
| 12.1XU                   | Vulnerable; migrate to 12.3(16) or |
|                          | later                              |
|--------------------------+------------------------------------|
| 12.1XV                   | Vulnerable; migrate to 12.3(16) or |
|                          | later                              |
|--------------------------+------------------------------------|
| 12.1XW                   | Vulnerable; migrate to 12.2(32) or |
|                          | later                              |
|--------------------------+------------------------------------|
| 12.1XY                   | Vulnerable; migrate to 12.2(32) or |
|                          | later                              |
|--------------------------+------------------------------------|
| 12.1XZ                   | Vulnerable; migrate to 12.2(32) or |
|                          | later                              |
|--------------------------+------------------------------------|
| 12.1YA                   | Vulnerable; migrate to 12.3(16) or |
|                          | later                              |
|--------------------------+------------------------------------|
| 12.1YB                   | Vulnerable; migrate to 12.3(16) or |
|                          | later                              |
|--------------------------+------------------------------------|
| 12.1YD                   | Vulnerable; migrate to 12.3(16) or |
|                          | later                              |
|--------------------------+------------------------------------|
| 12.1YE                   | Vulnerable; migrate to 12.3(16) or |
|                          | later                              |
|--------------------------+------------------------------------|
| 12.1YF                   | Vulnerable; migrate to 12.3(16) or |
|                          | later                              |
|--------------------------+------------------------------------|
| 12.1YH                   | Vulnerable; migrate to 12.3(16) or |
|                          | later                              |
|--------------------------+------------------------------------|
| 12.1YI                   | Vulnerable; migrate to 12.3(16) or |
|                          | later                              |
|--------------------------+------------------------------------|
| Affected 12.2-Based      | Rebuild       | Maintenance        |
| Release                  |               |                    |
|--------------------------+---------------+--------------------|
| 12.2                     |               | 12.2(32)           |
|--------------------------+------------------------------------|
| 12.2B                    | Vulnerable; migrate to 12.3(14)T5  |
|                          | or later                           |
|--------------------------+------------------------------------|
| 12.2BW                   | Vulnerable; migrate to 12.3(16) or |
|                          | later                              |
|--------------------------+------------------------------------|
| 12.2BY                   | Vulnerable; migrate to 12.3(14)T5  |
|                          | or later                           |
|--------------------------+------------------------------------|
| 12.2DD                   | Vulnerable; migrate to 12.3(14)T5  |
|                          | or later                           |
|--------------------------+------------------------------------|
| 12.2DX                   | Vulnerable; migrate to 12.3(14)T5  |
|                          | or later                           |
|--------------------------+------------------------------------|
| 12.2MX                   | Vulnerable; migrate to 12.3(14)T5  |
|                          | or later                           |
|--------------------------+------------------------------------|
|                          | 12.2(14)S16,  |                    |
|                          | available     |                    |
|                          | 9-Feb-06      |                    |
|                          |---------------+--------------------|
|                          | 12.2(18)S11,  |                    |
| 12.2S                    | available     |                    |
|                          | 16-Feb-06     |                    |
|                          |---------------+--------------------|
|                          | 12.2(25)S6    |                    |
|                          |---------------+--------------------|
|                          |               | 12.2(30)S          |
|--------------------------+------------------------------------|
| 12.2SU                   | Vulnerable; migrate to 12.3(14)T5  |
|                          | or later                           |
|--------------------------+------------------------------------|
| 12.2SW                   | 12.2(25)SW5   |                    |
|--------------------------+---------------+--------------------|
| 12.2SXB                  | 12.2(17d)SXB9 |                    |
|--------------------------+---------------+--------------------|
| 12.2SXD                  | 12.2(18)SXD6  |                    |
|--------------------------+---------------+--------------------|
| 12.2SXE                  | 12.2(18)SXE3  |                    |
|--------------------------+------------------------------------|
| 12.2SZ                   | Vulnerable; migrate to 12.2(30)S   |
|                          | or later                           |
|--------------------------+------------------------------------|
| 12.2XA                   | Vulnerable; migrate to 12.3(16) or |
|                          | later                              |
|--------------------------+------------------------------------|
| 12.2XB                   | Vulnerable; migrate to 12.3(16) or |
|                          | later                              |
|--------------------------+------------------------------------|
| 12.2XC                   | Vulnerable; migrate to 12.3(14)T5  |
|                          | or later                           |
|--------------------------+------------------------------------|
| 12.2XD                   | Vulnerable; migrate to 12.3(16) or |
|                          | later                              |
|--------------------------+------------------------------------|
| 12.2XG                   | Vulnerable; migrate to 12.3(16) or |
|                          | later                              |
|--------------------------+------------------------------------|
| 12.2XH                   | Vulnerable; migrate to 12.3(16) or |
|                          | later                              |
|--------------------------+------------------------------------|
| 12.2XJ                   | Vulnerable; migrate to 12.3(16) or |
|                          | later                              |
|--------------------------+------------------------------------|
| 12.2XK                   | Vulnerable; migrate to 12.3(16) or |
|                          | later                              |
|--------------------------+------------------------------------|
| 12.2XL                   | Vulnerable; migrate to 12.3(16) or |
|                          | later                              |
|--------------------------+------------------------------------|
| 12.2XM                   | Vulnerable; migrate to 12.3(16) or |
|                          | later                              |
|--------------------------+------------------------------------|
| 12.2XN                   | Vulnerable; migrate to 12.3(16) or |
|                          | later                              |
|--------------------------+------------------------------------|
| 12.2XQ                   | Vulnerable; migrate to 12.3(16) or |
|                          | later                              |
|--------------------------+------------------------------------|
| 12.2XS                   | Vulnerable; migrate to 12.3(16) or |
|                          | later                              |
|--------------------------+------------------------------------|
| 12.2XT                   | Vulnerable; migrate to 12.3(16) or |
|                          | later                              |
|--------------------------+------------------------------------|
| 12.2XU                   | Vulnerable; migrate to 12.3(16) or |
|                          | later                              |
|--------------------------+------------------------------------|
| 12.2XV                   | Vulnerable; migrate to 12.3(16) or |
|                          | later                              |
|--------------------------+------------------------------------|
| 12.2XW                   | Vulnerable; migrate to 12.3(16) or |
|                          | later                              |
|--------------------------+------------------------------------|
| 12.2YB                   | Vulnerable; migrate to 12.3(16) or |
|                          | later                              |
|--------------------------+------------------------------------|
| 12.2YC                   | Vulnerable; migrate to 12.3(16) or |
|                          | later                              |
|--------------------------+------------------------------------|
| 12.2YD                   | Vulnerable; migrate to 12.3(14)T5  |
|                          | or later                           |
|--------------------------+------------------------------------|
| 12.2YE                   | Vulnerable; migrate to 12.2(30)S   |
|                          | or later                           |
|--------------------------+------------------------------------|
| 12.2YH                   | Vulnerable; migrate to 12.3(16) or |
|                          | later                              |
|--------------------------+------------------------------------|
| 12.2YK                   | Vulnerable; migrate to 12.3(14)T5  |
|                          | or later                           |
|--------------------------+------------------------------------|
| 12.2YL                   | Vulnerable; migrate to 12.3(14)T5  |
|                          | or later                           |
|--------------------------+------------------------------------|
| 12.2YM                   | Vulnerable; migrate to 12.3(14)T5  |
|                          | or later                           |
|--------------------------+------------------------------------|
| 12.2YN                   | Vulnerable; migrate to 12.3(14)T5  |
|                          | or later                           |
|--------------------------+------------------------------------|
| 12.2YT                   | Vulnerable; migrate to 12.3(16) or |
|                          | later                              |
|--------------------------+------------------------------------|
| 12.2YU                   | Vulnerable; migrate to 12.3(14)T5  |
|                          | or later                           |
|--------------------------+------------------------------------|
| 12.2YW                   | Vulnerable; migrate to 12.3(14)T5  |
|                          | or later                           |
|--------------------------+------------------------------------|
| 12.2YX                   | Vulnerable; migrate to 12.3(14)T5  |
|                          | or later                           |
|--------------------------+------------------------------------|
| 12.2YY                   | Vulnerable; migrate to 12.3(14)T5  |
|                          | or later                           |
|--------------------------+------------------------------------|
| 12.2YZ                   | Vulnerable; migrate to 12.2(30)S   |
|                          | or later                           |
|--------------------------+------------------------------------|
| 12.2ZB                   | Vulnerable; migrate to 12.3(14)T5  |
|                          | or later                           |
|--------------------------+------------------------------------|
| 12.2ZC                   | Vulnerable; migrate to 12.3(14)T5  |
|                          | or later                           |
|--------------------------+------------------------------------|
| 12.2ZD                   | Vulnerable; contact TAC            |
|--------------------------+------------------------------------|
| 12.2ZE                   | Vulnerable; migrate to 12.3(16) or |
|                          | later                              |
|--------------------------+------------------------------------|
| 12.2ZF                   | Vulnerable; migrate to 12.3(14)T5  |
|                          | or later                           |
|--------------------------+------------------------------------|
| 12.2ZH                   | Vulnerable; contact TAC            |
|--------------------------+------------------------------------|
| 12.2ZJ                   | Vulnerable; migrate to 12.3(14)T5  |
|                          | or later                           |
|--------------------------+------------------------------------|
| 12.2ZL                   | Vulnerable; contact TAC            |
|--------------------------+------------------------------------|
| 12.2ZN                   | Vulnerable; migrate to 12.3(14)T5  |
|                          | or later                           |
|--------------------------+------------------------------------|
| 12.2ZP                   | Vulnerable; migrate to 12.3(14)T5  |
|                          | or later                           |
|--------------------------+------------------------------------|
| Affected 12.3-Based      | Rebuild       | Maintenance        |
| Release                  |               |                    |
|--------------------------+---------------+--------------------|
| 12.3                     |               | 12.3(16)           |
|--------------------------+------------------------------------|
| 12.3B                    | Vulnerable; migrate to 12.3(14)T5  |
|                          | or later                           |
|--------------------------+------------------------------------|
|                          | 12.3(11)T9    |                    |
|12.3T                     |---------------+--------------------|
|                          | 12.3(14)T5    |                    |
|--------------------------+------------------------------------|
| 12.3XA                   | Vulnerable; contact TAC            |
|--------------------------+------------------------------------|
| 12.3XB                   | Vulnerable; migrate to 12.3(14)T5  |
|                          | or later                           |
|--------------------------+------------------------------------|
| 12.3XD                   | Vulnerable; migrate to 12.3(14)T5  |
|                          | or later                           |
|--------------------------+------------------------------------|
| 12.3XE                   | Vulnerable; contact TAC            |
|--------------------------+------------------------------------|
| 12.3XF                   | Vulnerable; migrate to 12.3(14)T5  |
|                          | or later                           |
|--------------------------+------------------------------------|
| 12.3XG                   | Vulnerable; contact TAC            |
|--------------------------+------------------------------------|
| 12.3XH                   | Vulnerable; migrate to 12.3(14)T5  |
|                          | or later                           |
|--------------------------+------------------------------------|
| 12.3XI                   | 12.3(7)XI7    |                    |
|--------------------------+------------------------------------|
| 12.3XJ                   | Vulnerable; migrate to 12.3(14)YX  |
|                          | or later                           |
|--------------------------+------------------------------------|
| 12.3XK                   | Vulnerable; contact TAC            |
|--------------------------+------------------------------------|
| 12.3XM                   | Vulnerable; migrate to 12.3(14)T5  |
|                          | or later                           |
|--------------------------+------------------------------------|
| 12.3XQ                   | Vulnerable; migrate to 12.4(3) or  |
|                          | later                              |
|--------------------------+------------------------------------|
| 12.3XR                   | Vulnerable; contact TAC            |
|--------------------------+------------------------------------|
| 12.3XW                   | Vulnerable; migrate to 12.3(14)YX  |
|                          | or later                           |
|--------------------------+------------------------------------|
| 12.3XY                   | Vulnerable; migrate to 12.3(14)T5  |
|                          | or later                           |
|--------------------------+------------------------------------|
|                          | C828: Vulnerable; migrate to 12.4  |
|                          | (3) or later                       |
| 12.3YA                   |                                    |
|                          | SOHO9x, C82x: Vulnerable; contact  |
|                          | TAC                                |
|--------------------------+------------------------------------|
| 12.3YE                   | Vulnerable; migrate to 12.3(14)T5  |
|                          | or later                           |
|--------------------------+------------------------------------|
| 12.3YF                   | Vulnerable; migrate to 12.3(14)YX  |
|                          | or later                           |
|--------------------------+------------------------------------|
| 12.3YG                   | Vulnerable; contact TAC            |
|--------------------------+------------------------------------|
| 12.3YH                   | Vulnerable; contact TAC            |
|--------------------------+------------------------------------|
| 12.3YI                   | Vulnerable; contact TAC            |
|--------------------------+------------------------------------|
| 12.3YJ                   | Vulnerable; contact TAC            |
|--------------------------+------------------------------------|
| 12.3YK                   | Vulnerable; contact TAC            |
|--------------------------+------------------------------------|
| 12.3YM                   | 12.3(14)YM4   |                    |
|--------------------------+------------------------------------|
| 12.3YQ                   | Vulnerable; contact TAC            |
|--------------------------+------------------------------------|
| 12.3YS                   | Vulnerable; contact TAC            |
|--------------------------+------------------------------------|
| 12.3YT                   | Vulnerable; contact TAC            |
|--------------------------+------------------------------------|
| 12.3YU                   | Vulnerable; contact TAC            |
|--------------------------+------------------------------------|
| 12.3YX                   |               | 12.3(14)YX         |
|--------------------------+---------------+--------------------|
| Affected 12.4-Based      | Rebuild       | Maintenance        |
| Release                  |               |                    |
|--------------------------+---------------+--------------------|
|                          | 12.4(1c)      |                    |
|12.4                      |---------------+--------------------|
|                          |               | 12.4(3)            |
|--------------------------+---------------+--------------------|
| 12.4MR                   |               | 12.4(4)MR          |
|--------------------------+---------------+--------------------|
|                          | 12.4(2)T3     |                    |
|12.4T                     |---------------+--------------------|
|                          |               | 12.4(4)T           |
+---------------------------------------------------------------+

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@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 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@cisco.com


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. 

* 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.

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.

* AAA configuration command checks

Adding IOS configuration command authorization checking with the
global configuration command "aaa authorization config-commands" 
forces AAA command authorization to occur within Tcl Shell mode.

Caution: By enabling IOS configuration command authorization all 
commands within EXEC configuration mode will be subject to command 
authorization checks.

For further information on AAA authorization config-commands please
consult: http://www.cisco.com/univercd/cc/td/doc/product/software/
ios123/123cgcr/secur_r/sec_a1g.htm#wp1086510

* Deny tclsh IOS command within TACACS+ user profile

By ensuring that all user profiles defined within TACACS+ do not have
permission to execute the IOS EXEC command "tclsh" an administrator 
can prevent users from gaining additional command privilege 
escalation. Seek your vendor's TACACS+ server configuration guides to
ensure this is set correctly.

Caution:This will only be a valid workaround if all users who may 
access the device do not have access to "tclsh" command.
A single user who does have access to execute "tclsh" and does not 
exit as per the procedure described above, may unknowingly leave a 
Tcl Shell process running on one of the VTYs.

* Role Based CLI Views

The Role-Based CLI Access feature allows the network administrator to
define "views," which are a set of operational commands and
configuration capabilities that provide selective or partial access
to Cisco IOS EXEC and configuration (Config) mode commands. Views
restrict user access to Cisco IOS command-line interface (CLI) and
configuration information; that is, a view can define what commands
are accepted and what configuration information is visible. Thus,
network administrators can exercise better control over access to
Cisco networking devices.

For further information on CLI-Views: http://www.cisco.com/univercd/
cc/td/doc/product/software/ios124/124cg/hsec_c/part30/hclivws.htm

Revision History
================

+------------------------------------------------------------------+
| Revision 1.0 | 2006-January-25 | 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 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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You have received this e-mail bulletin as a result of your organisation's
registration with AusCERT. The mailing list you are subscribed to is
maintained within your organisation, so if you do not wish to continue
receiving these bulletins you should contact your local IT manager. If
you do not know who that is, please send an email to auscert@auscert.org.au
and we will forward your request to the appropriate person.

NOTE: Third Party Rights
This security bulletin is provided as a service to AusCERT's members.  As
AusCERT did not write the document quoted above, AusCERT has had no control
over its content. The decision to follow or act on information or advice
contained in this security bulletin is the responsibility of each user or
organisation, and should be considered in accordance with your organisation's
site policies and procedures. AusCERT takes no responsibility for consequences
which may arise from following or acting on information or advice contained in
this security bulletin.

NOTE: This is only the original release of the security bulletin.  It may
not be updated when updates to the original are made.  If downloading at
a later date, it is recommended that the bulletin is retrieved directly
from the author's website to ensure that the information is still current.

Contact information for the authors of the original document is included
in the Security Bulletin above.  If you have any questions or need further
information, please contact them directly.

Previous advisories and external security bulletins can be retrieved from:

        http://www.auscert.org.au/render.html?cid=1980

If you believe that your computer system has been compromised or attacked in 
any way, we encourage you to let us know by completing the secure National IT 
Incident Reporting Form at:

        http://www.auscert.org.au/render.html?it=3192

===========================================================================
Australian Computer Emergency Response Team
The University of Queensland
Brisbane
Qld 4072

Internet Email: auscert@auscert.org.au
Facsimile:      (07) 3365 7031
Telephone:      (07) 3365 4417 (International: +61 7 3365 4417)
                AusCERT personnel answer during Queensland business hours
                which are GMT+10:00 (AEST).
                On call after hours for member emergencies only.
===========================================================================

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