[Full-Disclosure] Cisco Security Advisory: Cisco IOS Software Processing of SAA Packets

From: Cisco Systems Product Security Incident Response Team (psirt_at_cisco.com)
Date: 05/15/03

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    Cisco Security Advisory: Cisco IOS Software Processing of SAA Packets

    Revision 1.0

    For Public Release 2003 May 15 15:00 UTC (GMT)

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

    Contents

        Summary
        Affected Products
        Details
        Impact
        Software Versions and Fixes
        Obtaining Fixed Software
        Workarounds
        Exploitation and Public Announcements
        Status of This Notice: FINAL
        Distribution
        Revision History
        Cisco Security Procedures

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

    Summary
    =======
    The Service Assurance Agent (SAA) is the new name for the Response Time
    Reporter (RTR) feature.

    The router is vulnerable only if the RTR responder is enabled. When the
    router receives a malformed RTR packet, it will crash. RTR is disabled by
    default. Although RTR was introduced in Cisco IOSŪ Software Release 11.2,
    only the following main releases are vulnerable:

      * 12.0S, SC, ST, SL, SP, SX
       
      * 12.1, E, EA, EC, EX, EY
       
      * 12.2, DA, S
       
    For the complete list please see the Software Versions and Fixes section.

    No other Cisco product is vulnerable.

    There is no workaround short of disabling the RTR responder. It is
    possible to mitigate the vulnerability by applying the access control
    list (ACL) on the router.

    This advisory is available at http://www.cisco.com/warp/public/707/
    cisco-sa-20030515-saa.shtml.

    Affected Products
    =================
    This vulnerability affects the following main Cisco IOS Software releases
    (some X releases are also affected, and those details are in the Software
    Version and Fixes section).

    +-----------------------------------------+
    | Major | Vulnerable Releases |
    | Release | |
    |---------+-------------------------------|
    | 12.0S | 15, 16, 17, 18, 19, 21 |
    |---------+-------------------------------|
    | 12.0SC | 15, 16 |
    |---------+-------------------------------|
    | 12.0SL | 15, 17, 19 |
    |---------+-------------------------------|
    | 12.0ST | 16, 17, 18, 19, 20, 21 |
    |---------+-------------------------------|
    | 12.0SP | 19, 20 |
    |---------+-------------------------------|
    | 12.0SX | 21 |
    |---------+-------------------------------|
    | 12.1 | 10, 10a, 11, 11a, 11b, 12, |
    | | 12a, 12b, 12c, 13, 14, 14.5 |
    |---------+-------------------------------|
    | 12.1E | 10, 11b, 11.5 |
    |---------+-------------------------------|
    | 12.1EA | 8, 9 |
    |---------+-------------------------------|
    | 12.1EC | 10, 10.5 |
    |---------+-------------------------------|
    | 12.1EX | 10 |
    |---------+-------------------------------|
    | 12.1EY | 10 |
    |---------+-------------------------------|
    | 12.2 | 6.8a, 7, 7a, 7b, 7c |
    |---------+-------------------------------|
    | 12.2DA | 7, 9.4 |
    |---------+-------------------------------|
    | 12.2S | 9, 10.5 |
    +-----------------------------------------+

    No other Cisco products are affected.

    Details
    =======
    The RTR feature allows you to monitor network performance, network
    resources, and applications by measuring response times and availability.
    With this feature you can perform troubleshooting, problem notifications,
    and problem analysis based on response time reporter statistics.

    A router is vulnerable only if the RTR responder is enabled. In order to
    verify this, check the router's configuration. Execute the following
    command while logged on a router:

        Router>show rtr responder
             RTR Responder is: Enabled
             Number of control messages received: 0 Number of errors: 0
             Recent sources:
             Recent error sources:

    If you notice the line "RTR Responder is: Enabled," then you are
    vulnerable.

    Alternatively, you can use this procedure:

        Router>show ip socket
             show ip socket
             Proto Remote Port Local Port In Out Stat TTY
    OutputIF
             ....
              17 0.0.0.0 0 10.0.0.1 1967 0 0 89 0

    If you notice a line as in the example above where the router is
    listening to the port 1967, then you are vulnerable.

    For Cisco IOS Software, this vulnerability is documented as two Cisco Bug
    IDs: CSCdx17916 and CSCdx61997.

    Impact
    ======
    By sending malformed RTR packets, it is possible to crash the router.

    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," "Interim," 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). When selecting a release, keep
    in mind the following definitions.

      * Maintenance - The most heavily tested, stable, and highly recommended
        release of a release train in any given row of the table.
       
      * Rebuild - Constructed from the previous maintenance or major release
        in the same train, it contains the fix for a specific defect.
        Although it receives less testing, it contains only the minimal
        changes necessary to repair the vulnerability.
       
      * Interim - Built at regular intervals between maintenance releases and
        receives less testing. Interims should be selected only if there is
        no other suitable release that addresses the vulnerability. Interim
        images should be upgraded to the next available maintenance release
        as soon as possible. Interim releases are not available through
        manufacturing, and usually they are not available for customer
        download from http://www.cisco.com without prior arrangement with the
        Cisco TAC.
       
    In all cases, customers should exercise caution to confirm that the
    devices to be upgraded contain sufficient memory and that current
    hardware and software configurations will continue to be supported
    properly by the new software release. If the information is not clear,
    contact the Cisco TAC for assistance as shown in the Obtaining Fixed
    Software section below.

    More information on Cisco IOS software release names and abbreviations is
    available at http://www.cisco.com/warp/public/620/1.html.

    The fixes will be available at the Software Center located at http://
    www.cisco.com/tacpage/sw-center/.

    +-------------------------------------------------------------------------+
    | Major | Description | Availability of Repaired Releases* |
    | Release | or Platform | |
    |------------------------+------------------------------------------------|
    | Affected Earlier | Rebuild | Interim** | Maintenance |
    | Releases | | | |
    |------------------------+------------------------------------------------|
    | 11.1 and | | |
    | earlier, | Numerous | Not vulnerable |
    | all | | |
    | variants | | |
    |------------------------+------------------------------------------------|
    | Affected 11.2-Based | Rebuild | Interim** | Maintenance |
    | Releases | | | |
    |------------------------+------------------------------------------------|
    | 11.2 | Numerous | Not vulnerable |
    | variants | | |
    |------------------------+------------------------------------------------|
    | Affected 11.3-Based | Rebuild | Interim** | Maintenance |
    | Releases | | | |
    |------------------------+------------------------------------------------|
    | 11.3 | Numerous | Not vulnerable |
    | variants | | |
    |------------------------+------------------------------------------------|
    | Affected 12.0-Based | Rebuild | Interim** | Maintenance |
    | Releases | | | |
    |------------------------+------------+-----------------+-----------------|
    | | Core/ISP | | | |
    | | Support: | | | |
    | 12.0S | GSR, RSP, | 12.0(21)S3 | 12.0(21.03)S | |
    | | c7200, | | | |
    | | Cat6000 | | | |
    |----------+-------------+------------------------------------------------|
    | | Cable/ | Not planned |
    | 12.0SC | Broadband | |
    | | ISP: | Migrate to 12.1EC release |
    | | ubr7200 | |
    |----------+-------------+------------------------------------------------|
    | | 10000 ESR: | If using Pre1 card, then migrate to 12.0ST or |
    | 12.0SL | c10k | 12.0S |
    | | | For Pre card the date is not yet determined. |
    |----------+-------------+------------------------------------------------|
    | 12.0SP | c10720 | 12.0(20)SP3| 12.0(20.04)SP2 | |
    |----------+-------------+------------+-----------------+-----------------|
    | | MPLS/Tag | 12.0(19)ST5| | |
    | 12.0ST | Switching, | | | |
    | | GSR 12000, | 12.0(21)ST2| | |
    | | 7200, 7500 | | | |
    |----------+-------------+------------------------------------------------|
    | | Short-lived | |
    | | early | |
    | 12.0SX | deployment | To be determined |
    | | release | |
    | | 10000 ESR: | |
    | | c10k | |
    |----------+-------------+------------------------------------------------|
    | 12.0SY | | | 12.0(21.03)SY | 12.0(22)SY |
    |----------+-------------+------------+-----------------+-----------------|
    | | Short-lived | | | |
    | | early | | | |
    | 12.0WC | deployment | 12.0(5)WCa | | |
    | | release for | | | |
    | | 2900XL and | | | |
    | | 3500XL | | | |
    |----------+-------------+------------------------------------------------|
    | | Short-lived | Not planned |
    | 12.0XE | early | |
    | | deployment | Migrate to 12.2 release or later |
    | | release | |
    |------------------------+------------------------------------------------|
    | Affected 12.1-Based | Rebuild | Interim** | Maintenance |
    | Releases | | | |
    |------------------------+------------+-----------------+-----------------|
    | | General | | | |
    | | Deployment | | | |
    | 12.1 | (GD) | | 12.1(18.1) | 12.1(18) |
    | | candidate: | | | |
    | | all | | | |
    | | platforms | | | |
    |----------+-------------+------------+-----------------+-----------------|
    | | Core/ISP | | | |
    | 12.1E | Support: | | 12.1(12.5)E | 12.1(13)E |
    | | GSR, RSP, | | | |
    | | c7200 | | | |
    |----------+-------------+------------+-----------------+-----------------|
    | 12.1EA | Catalyst | 12.1(8)EA1c| | |
    | | 2950 | | | |
    |----------+-------------+------------+-----------------+-----------------|
    | | Early | | | |
    | | Deployment | | | |
    | 12.1EC | (ED): | | 12.1(12c)EC | |
    | | ubr7200, | | | |
    | | UBR Headend | | | |
    | | platforms | | | |
    |----------+-------------+------------+-----------------+-----------------|
    | | Early | | | |
    | | Deployment | | | |
    | 12.1EW | release, | | | 12.1(11b)EW |
    | | limited | | | |
    | | platforms | | | |
    |----------+-------------+------------+-----------------+-----------------|
    | | Early | | | |
    | | Deployment | | | |
    | 12.1EW | release, | | |12.1(11b)EW(0.46)|
    | | limited | | | |
    | | platforms | | | |
    |----------+-------------+------------+-----------------+-----------------|
    | 12.1EX | Catalyst | | | 12.1(11b)EX |
    | | 6000 | | | |
    |----------+-------------+------------------------------------------------|
    | | Short-lived | |
    | 12.1XF | early | Not planned Migrate to 12.1(5)T or later |
    | | deployment | |
    | | release | |
    |----------+-------------+------------------------------------------------|
    | | Short-lived | |
    | 12.1XG | early | Not planned Migrate to 12.1(1)T or later |
    | | deployment | |
    | | release | |
    |----------+-------------+------------------------------------------------|
    | | Short-lived | |
    | 12.1YB | early | Not planned Migrate to 12.1(2)T or later |
    | | deployment | |
    | | release | |
    |----------+-------------+------------------------------------------------|
    | | Short-lived | |
    | 12.1YC | early | Not planned Migrate to 12.1(4)T or later |
    | | deployment | |
    | | release | |
    |------------------------+------------------------------------------------|
    | Affected 12.2-Based | Rebuild | Interim** | Maintenance |
    | Releases | | | |
    |------------------------+------------+-----------------+-----------------|
    | | General | | | |
    | | Deployment | | | |
    | 12.2 | (GD) | | 12.2(10.4) | 12.2(10) |
    | | candidate: | | | |
    | | all | | | |
    | | platforms | | | |
    |----------+-------------+------------+-----------------+-----------------|
    | | Early | | | |
    | | Deployment | | | |
    | 12.2(4)B | for 6400, | | 12.2(13.3)B | |
    | | 7200 and | | | |
    | | 7400 | | | |
    |----------+-------------+------------------------------------------------|
    | | Early | |
    | | Deployment | |
    | 12.2BC | for uBR7000 | To be determined |
    | | and | |
    | | uBR10000 | |
    |----------+-------------+------------------------------------------------|
    | | Early | Not planned |
    | 12.2BY | Deployment | |
    | | release | Migrate to 12.2B releases |
    |----------+-------------+------------------------------------------------|
    | | Early | | | |
    | 12.2BZ | Deployment | | | 12.2(15)BZ |
    | | release | | | |
    |----------+-------------+------------+-----------------+-----------------|
    | | Early | | | |
    | | deployment | | | |
    | 12.2DA | release | | 12.2(11.4)DA | 12.2(12)DA |
    | | xDSL | | | |
    | | support: | | | |
    | | 6100, 6200 | | | |
    |----------+-------------+------------+-----------------+-----------------|
    | | Early | | | |
    | | deployment | | | |
    | 12.2MB | release for | 12.2(4)MB5 | | |
    | | 2600 and | | | |
    | | 7500 | | | |
    |----------+-------------+------------+-----------------+-----------------|
    | 12.2S | Core ISP | | 12.2(11.1)S | |
    | | support | | | |
    |----------+-------------+------------+-----------------+-----------------|
    | | Early | | | |
    | 12.2XC | deployment | 12.2(1a)XC5| | |
    | | release | | | |
    |----------+-------------+------------------------------------------------|
    | | ICS7750/820 | Not planned |
    | 12.2XD | /soho70 | |
    | | | Migrate to 12.2(8)YN or later |
    |----------+-------------+------------------------------------------------|
    | | 806, 828, | Not planned |
    | 12.2XE | soho78 | |
    | | | Migrate to 12.2(8)T or later |
    |----------+-------------+------------------------------------------------|
    | | 1700 820/ | Not planned |
    | 12.2XH | 800/soho70 | |
    | | | Migrate to 12.2(8)T or later |
    |----------+-------------+------------------------------------------------|
    | | | Not planned |
    | 12.2XI | 820/soho | |
    | | | Migrate to 12.2(12)T or later |
    |----------+-------------+------------------------------------------------|
    | | | Not planned |
    | 12.2XJ | 1700 | |
    | | | Migrate to 12.2(4)YB or later |
    |----------+-------------+------------------------------------------------|
    | 12.2XK | 820/soho | | | 12.2(2)XK3 |
    |----------+-------------+------------+-----------------+-----------------|
    | 12.2XL | 1700 820/ | | | 12.2(4)XL5 |
    | | 800/soho70 | | | |
    |----------+-------------+------------------------------------------------|
    | | Short-lived | Not planned |
    | 12.2XM | early | |
    | | deployment | Migrate to 12.2(8)YB or later |
    | | release | |
    |----------+-------------+------------------------------------------------|
    | | Short-lived | | | |
    | 12.2YA | early | 12.2(4)YA3 | | |
    | | deployment | | | |
    | | release | | | |
    |----------+-------------+------------------------------------------------|
    | | Short-lived | Not planned |
    | 12.2YB | early | |
    | | deployment | Migrate to 12.2(8)YB or later |
    | | release | |
    |----------+-------------+------------------------------------------------|
    | | Short-lived | | | |
    | 12.2YC | early | 12.2(4)YC4 | | |
    | | deployment | | | |
    | | release | | | |
    |----------+-------------+------------------------------------------------|
    | | Cisco | |
    | | Packet Data | |
    | 12.2YF | Serving | Release date to be decided |
    | | Node | |
    | | ics7700 | |
    |----------+-------------+------------------------------------------------|
    | | Short-lived | | | |
    | 12.2YG | early | | | 12.2(4)YG |
    | | deployment | | | |
    | | release | | | |
    |----------+-------------+------------+-----------------+-----------------|
    | | Short-lived | | | |
    | 12.2YH | early | | | 12.2(4)YH |
    | | deployment | | | |
    | | release | | | |
    |-------------------------------------------------------------------------|
    | Notes |
    |-------------------------------------------------------------------------|
    | * All dates are estimated and subject to change. |
    | |
    | ** Interim releases are subjected to less rigorous testing than regular |
    | maintenance releases, and may have serious bugs. |
    +-------------------------------------------------------------------------+

    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. 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 the Cisco Connection Online Software Center at
    http://www.cisco.com/public/sw-center/sw-usingswc.shtm.

    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). In those cases, customers may only upgrade to a
    later version of the same release as indicated by the applicable row in
    the Software Versions and Fixes table.

    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. 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
    ===========
    There is no workaround short of disabling the RTR responder. It is
    possible to mitigate the vulnerability by applying the ACL on the router.

    If you want to disable the RTR, you need to execute the following
    commands:

        Router#conf t
        Enter configuration commands, one per line. End with CNTL/Z.
        Router(config)#no rtr responder
        Router(config)#exit
        Router#copy running-config startup-config

    If you want to block all offending packets on your network edge, then you
    should create an ACL, or modify an existing one, to contain an entry
    resembling:

        Router#conf t
        Enter configuration commands, one per line. End with CNTL/Z.
        Router(config)#access-list 101 deny udp any any eq 1967
        Router(config)#interface eth0
        Router(config)#ip access-group 101 in

    In this example the interface eth0 is assumed to be facing toward the
    network edge. You will have to substitute it for the correct interface on
    your router.

    This will prevent any packet that is destined to the port 1967/UDP from
    entering your network. If you need to enable these packets to traverse
    your network, then the ACL must exclude only your internal routers.

    In addition to filtering packets at the network edge, you may apply
    filtering on the device itself and permit packets only from known good
    sources. This will contribute to the overall mitigation of this issue.

        Router#conf t
        Enter configuration commands, one per line. End with CNTL/Z.
        Router(config)#access-list 101 permit udp 10.0.0.1 10.0.0.10 eq 1967
        Router(config)#access-list 101 deny udp any 10.0.0.10 eq 1967
        Router(config)#interface eth0
        Router(config)#ip access-group 101 in

    In this example, 10.0.0.1 is the legitimate source and 10.0.0.10 is the
    address of the router itself.

    Exploitation and Public Announcements
    =====================================
    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 advisory, all of the facts have been checked to
    the best of our ability. Cisco does not anticipate issuing updated
    versions of this advisory unless there is some material change in the
    facts. Should there be a significant change in the facts, Cisco may
    update this advisory.

    A stand-alone 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.

    Distribution
    ============
    This advisory will be posted on Cisco's worldwide website at http://
    www.cisco.com/warp/public/707/cisco-sa-20030515-saa.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 recipients.

      * cust-security-announce@cisco.com
      * bugtraq@securityfocus.com
      * full-disclosure@lists.netsys.com
      * vulnwatch@vulnwatch.org
      * 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 advisory, if any, will be placed on Cisco's
    worldwide website, but may or may not be actively announced on mailing
    lists or newsgroups. Users concerned about this problem are encouraged to
    check the above URL for any updates.

    Revision History

    +-----------------------------------------+
    | Revision | 2003- May-15, | Initial |
    | 1.0 | 15:00 UTC | public |
    | | (GMT) | 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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