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

From: Cisco Systems Product Security Incident Response Team (psirt@cisco.com)
Date: 04/24/03

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    From: Cisco Systems Product Security Incident Response Team <psirt@cisco.com>
    To: vulnwatch@vulnwatch.org
    Date: Thu, 24 Apr 2003 08:00:00 -0700 (PDT)
    
    

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    Cisco Security Advisory: Cisco Catalyst Enable Password Bypass
      Vulnerability
    =======================================================================

    Revision 1.0

    For Public Release 2003 April 24 08:00 (GMT)

    - ------------------------------------------------------------------------

    Summary
    =======

    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 IOSŪ
    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@cisco.com <mailto: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
    <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@cisco.com" or
    "security-alert@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@cisco.com
        * bugtraq@securityfocus.com
        * full-disclosure@lists.netsys.com
        * first-teams@first.org (includes CERT/CC)
        * cisco@spot.colorado.edu
        * cisco-nsp@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.

    - ------------------------------------------------------------------------

    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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