[nsp] Cisco Security Advisory: Cisco Catalyst Enable Password Bypass Vulnerability

Thu Apr 24 09:00:00 EDT 2003

Cisco Catalyst software permits unauthorized access to the enable mode
in the 7.5(1) release. Once initial access is granted, access can be
obtained for the higher level "enable" mode without a password. This
problem is resolved in version 7.6(1). Customers with vulnerable
releases are urged to upgrade as soon as possible.

This issue is documented in Cisco Bug ID CSCea42030.

This advisory is available at
http://www.cisco.com/warp/public/707/cisco-sa-20030424-catos.shtml.

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

All users of Cisco Catalyst 4000, 6000, and 6500 with the Catalyst OS
software version 7.5(1) only.

No other releases of Cisco Catalyst OS software are affected by this
vulnerability. Additionally, Catalyst hardware running Cisco IOS®
software is not affected by this vulnerability.

No other Cisco products are affected by this vulnerability.

Detail
======

Anyone who can obtain command line access to an affected switch can
bypass password authentication to obtain "enable" mode access without
knowledge of the "enable" password. If local user authentication is
enabled, a valid username can be used to gain access to the switch
without a valid password. This same local user could then enter enable
without a valid password.

Command line access is provided through the console, telnet access, or
ssh access methods; http access mode is not affected.

This problem was introduced with the local user authentication feature
in software version 7.5(1), and is corrected in version 7.6(1).

Bug ID
CSCea42030

Impact
======

This vulnerability permits unauthorized access to the configuration mode
and unauthorized configuration changes on a Catalyst switch.

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

This vulnerability is repaired in version 7.6(1) which is currently
available.

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

Cisco is offering free software upgrades to remedy this vulnerability
for all affected customers. Customers may only install and expect
support for the feature sets they have purchased.

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 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 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)
    * email: tac at cisco.com <mailto:tac at 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
<http://www.cisco.com/warp/public/707/cisco-sa-20030424-catos.shtml> 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

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

Strictly limiting telnet and/or ssh access to the device will prevent
the initial connection required to exploit this vulnerability. Telnet
and/or ssh access can be controlled with the following command set:

     set ip permit <address> <mask> telnet
     set ip permit <address> <mask> ssh  

     set ip permit enable

This command set will deny all traffic not specified in the permit
statements for each protocol.

Additionally, out-of-band management solutions, isolated management VLAN
configurations, and AAA authentication services can help mitigate this
vulnerability by limiting the initial access necessary for exploitation.

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

The Cisco PSIRT is not aware of any public announcements or malicious
use of the vulnerabilities described in this advisory.  This issue was
reported to Cisco by a customer.

Status of This Notice: Final
============================

This is a final notice. Although Cisco cannot guarantee the accuracy of
all statements in this notice, all 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.

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

This notice will be posted on Cisco's worldwide website at
http://www.cisco.com/warp/public/707/cisco-sa-20030424-catos.shtml
<REPLACE%20ME>. 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
    * bugtraq at securityfocus.com
    * full-disclosure at lists.netsys.com
    * first-teams at first.org (includes CERT/CC)
    * cisco at spot.colorado.edu
    * cisco-nsp at puck.nether.net
    * comp.dcom.sys.cisco
    * Various internal Cisco mailing lists

Future updates of this notice, if any, will be placed on Cisco's
worldwide web. Users concerned about this problem are encouraged to
check the URL given above for any updates.

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

Revision 1.0 24-April-2003 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/warp/public/707/sec_incident_response.shtml. 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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This notice is Copyright 2003 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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