Due to technical difficulties, the cust-security-announcecisco.com
mailing list did not receive the attached security advisory at the time
it was originally mailed. We have taken steps to make sure it doesn't
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Since the time of the original announcement, the advisory has been
updated. Please be sure to see the on-line version of this advisory at
http://www.cisco.com/warp/public/707/ios-snmp-ilmi-vuln-pub.shtml for
the very latest information.

Note that the status of this advisory is still "interim", which means we
do expect to update the notice soon. Updates are usually NOT sent to
the mailing lists, so we encourage you to check the URL mentioned above
to find out the latest information.

Please contact us if you have any comments or questions.

        Product Security Incident Response Team, psirtcisco.com

-----BEGIN PGP SIGNED MESSAGE-----

 Cisco Security Advisory:

 Cisco IOS Software SNMP Read-Write ILMI Community String Vulnerability
                                      
  Revision 1.0: INTERIM
  
  For Public Release 2001 February 27 04:00 US/Eastern (UTC+0500)
     _______________________________________________________________
   
Summary

   Cisco IOS software releases based on versions 11.x and 12.0 contain
   a defect that allows a limited number of SNMP objects to be viewed
   and modified without authorization using a undocumented ILMI
   community string. Some of the modifiable objects are confined to the
   MIB-II system group, such as "sysContact", "sysLocation", and
   "sysName", that do not affect the device's normal operation but that
   may cause confusion if modified unexpectedly. The remaining objects
   are contained in the LAN-EMULATION-CLIENT and PNNI MIBs, and
   modification of those objects may affect ATM configuration. An
   affected device might be vulnerable to a denial-of-service attack if
   it is not protected against unauthorized use of the ILMI community
   string.
   
   The vulnerability is only present in certain combinations of IOS
   releases on Cisco routers and switches. ILMI is a necessary
   component for ATM, and the vulnerability is present in every IOS
   release that contains the supporting software for ATM and ILMI
   without regard to the actual presence of an ATM interface or the
   physical ability of the device to support an ATM connection.
   
   To remove this vulnerability, Cisco is offering free software
   upgrades for all affected platforms. The defect is documented in
   DDTS record CSCdp11863.
   
   In lieu of a software upgrade, a workaround can be applied to
   certain IOS releases by disabling the ILMI community or "*ilmi" view
   and applying an access list to prevent unauthorized access to SNMP.
   Any affected system, regardless of software release, may be
   protected by filtering SNMP traffic at a network perimeter or on
   individual devices.
   
   This notice will be posted at
   http://www.cisco.com/warp/public/707/ios-snmp-ilmi-vuln-pub.shtml.
   
Affected Products

   The vulnerability is present only in certain releases of Cisco IOS
   Software versions 11.x and 12.0 for router and switch products that
   include support for Asynchronous Transfer Mode (ATM) networking and
   Interim Local Management Interface (ILMI), and it is present without
   regard to any physical capability for supporting an ATM interface.
   
   Cisco IOS Software versions based on 10.3 and earlier do not contain
   the vulnerability. The defect was introduced in 11.0(0.2). All Cisco
   IOS software releases of 12.1 and later have been repaired and are
   not vulnerable to the defect described in this advisory.
   
   To determine the software running on a Cisco product, log in to the
   device and issue the command "show version" to display the system
   banner. Cisco IOS software will identify itself as "Internetwork
   Operating System Software" or simply "IOS (tm)". The image name will
   be displayed between parentheses, usually on the next line of
   output, followed by "Version" and the IOS release name. Other Cisco
   devices will not have the "show version" command or will give
   different output.
   
   The following example identifies a Cisco product running IOS release
   12.0(3) with an installed image name of C2500-IS-L:

       Cisco Internetwork Operating System Software IOS (tm)
       2500 Software (C2500-IS-L), Version 12.0(3), RELEASE SOFTWARE
       
   The device is not vulnerable to the defect described in this
   advisory since the model 2500 router is specifically excluded in the
   list of unaffected products shown below.
   
   Cisco devices that may be running an affected IOS software release
   include, but are not limited to:

     * Cisco 1400 and 1700 series.

     * Cisco 2600 (except that c2600-c-mz, c2600-d-mz, c2600-i-mz,
       c2600-io3-mz, and c2600-ix-mz images are not vulnerable).

     * Catalyst 2900 ATM, 2900XL, and 2948g series.

     * Cisco 3620 (except that c3620-d-mz, c3620-i-mz, c3620-io3-mz,
       and c3620-ix-mz images are not vulnerable).

     * Cisco 3640 (except that c3640-d-mz, c3640-i-mz, c3640-io3-mz,
       and c3640-ix-mz images are not vulnerable).

     * Cisco 3660 (except that c3660-d-mz, c3660-i-mz, and c3660-ix-mz
       images are not vulnerable).

     * Cisco MC3810 (except that mc3810-i-mz, mc3810-is-mz,
       mc3810-is56i-mz, and mc3810-js-mz images are not vulnerable).

     * Catalyst 4232, 4840g, 5000 RSFC series switches.

     * Cisco 4500, 4700, and 5800 DSC series.

     * Cisco 6200, 6400 NRP, and 6400 NSP series.

     * Catalyst MSM (c6msm), 6000 Hybrid Mode (c6msfc), and 6000 Native
       Mode (c6sup).

     * Cisco RSM, 7000, 7010, 7100, 7200, ubr7200, and 7500 series.

     * Catalyst 8510CSR, 8510MSR, 8540CSR, and 8540MSR series.

     * Cisco 10000 ESR and 12000 GSR series.

     * LS1010 and Cisco 6260-NI2.

     * DistributedDirector (except that igs-w3 images are not
       vulnerable).
       
   Cisco products that are not affected by this vulnerability either
   because they have no support for ATM and ILMI, or because they do
   not run IOS include, but are not limited to:

     * Catalyst ATM blade (runs possibly affected code, but an SNMP
       connection to the blade is not possible).

     * Cisco 800 and 805 series.

     * Cisco Universal Broadband Routers ubr900 and ubr920.

     * Cisco 1003, 1004, and 1005 series.

     * Cisco 1600, 2500, 2800, 4000 series.

     * Cisco 2500 Fixed Frad.

     * Cisco 3800 (not to be confused with MC3810).

     * Cisco 5100, 5200, and 5300 series access servers.

     * Catalyst 6000 Supervisor Module.

     * Cisco PIX Firewall.

     * Aironet and Cisco/Aironet wireless products.

     * CS11000, Cache Engine, LocalDirector, and network scaling
       products (except that the Distributed Director might be
       affected).

     * VPN products such as Altiga concentrators.

     * Host-based network management or access management products.

     * Cisco IP Telephony and telephony management software (except
       those that are hosted on a vulnerable IOS platform).

     * Voice gateways and convergence platforms (except those that are
       hosted on a vulnerable IOS platform).

     * Optical switch products such as the ONS 15000 series.
       
Details

   ILMI (Interim Local Management Interface) is an independent industry
   standard used for configuration of ATM (Asynchronous Transfer Mode)
   interfaces. The standard specifies the use of mechanisms and formats
   previously defined by SNMP (Simple Network Management Protocol).
   Although it is based on SNMP, ILMI communication actually occurs
   using a transport other than IP (Internet Protocol) that traverses
   only the physical ATM link. ILMI is essential to functions such as
   ATM auto-discovery and LANE (LAN Emulation).
   
   SNMP "objects" are variables that are organized into a MIB
   (Management Information Base). The MIB has a tree structure and
   contains both operational (read-only) data as well as configuration
   (read-write) options. By specifying a community string of "ILMI" in
   an SNMP request, access can be obtained to read the objects in three
   specific parts of the overall management tree structure on any
   device affected by this vulnerability: the MIB-II system group, the
   LAN-EMULATION-CLIENT MIB, and the PNNI (Private Network-to-Network
   Interface) MIB. A subset of objects in each part can be modified
   using the same "ILMI" community string.
   
   The MIB-II system group contains basic information about the device
   itself. The number of objects that can be modified is limited.
   Examples include:

     * system.sysContact: The contact information for the person or
       organization responsible for managing the device.

     * system.sysLocation: A description of the physical location where
       the device is installed or operating.

     * system.sysName: The hostname of the device, how it identifies
       itself at the console prompt. (This might not be the same name
       by which the device is known to other hosts on the network.)
       
   Most of the objects in the system MIB are read-only and cannot be
   changed via SNMP, such as the time elapsed since the previous
   restart and textual descriptions of the device's hardware and
   software.
   
   Numerous objects can be viewed in the LAN-EMULATION-CLIENT MIB and
   PNNI MIB, and modification of some of the read-write objects can
   have an affect on ATM operation of the device. The objects in the
   LAN-EMULATION-CLIENT MIB can only be viewed or modified if LANE has
   already been configured on the device.
   
   Access to SNMP in Cisco IOS software can be limited by applying
   access control lists (ACLs), by modifying or removing the SNMP view,
   by removing the community string from the running configuration, or
   by disabling the SNMP service. Any SNMP query that does not meet the
   criteria for access is promptly discarded when such protective
   measures are in place. If a query does meet the criteria for access,
   then a response is formulated and sent.
   
   It is possible to configure the device so that the ILMI community
   string is unavailable in all IOS 11.1 and higher releases. The
   particular method selected to accomplish this depends on the
   specific IOS release and configuration.
   
   This defect is documented as CSCdp11863. The vulnerability is
   repaired by imposing a test such that an SNMP request using the
   "ILMI" community string will only be recognized if it has been
   transported by ILMI.
   
   ATM functionality was added in various 10.x releases of Cisco IOS
   software. However, the function containing the defect was introduced
   when support for ILMI and other ATM features was added in IOS
   release 11.0(0.2). Therefore, all prior releases are not vulnerable.
   
Impact

   If SNMP requests can be received by an affected device, then certain
   MIB objects can be viewed without proper authorization, causing a
   violation of confidentiality.
   
   A subset of the readable MIB objects can be modified without
   authorization to cause a failure of integrity. For example, the
   hostname can be modified so as to confuse network adminstrators, or
   the contact and location information could be changed with a goal of
   disrupting operations or embarassing whoever is responsible for the
   device.
   
   Objects in the LAN-EMULATION-CLIENT and PNNI MIBs can be viewed and
   modified, thus resulting in changes to the operation of ATM
   functions. If ATM is in use on the device, this may result in a
   failure of availability.
   
   Any affected device that is not otherwise protected against the
   receipt of SNMP packets is vulnerable to a denial-of-service (DoS)
   attack by flooding the SNMP port with read or write requests.
   
Software Versions and Fixes

   The following table summarizes the known affected Cisco IOS software
   releases and the earliest estimated dates of availability for fixed
   releases. All dates are tentative and subject to change.
   
   Each row of the table 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
   and the anticipated date of availability for each are listed in the
   "Rebuild", "Interim", and "Maintenance" columns. If a device is
   running an earlier release that is known to be vulnerable, it should
   be upgraded to at least the indicated version.
   
   When selecting a release, keep in mind the following definitions:
   
   Maintenance
          Most heavily tested and highly recommended release of any
          label in a 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 effect the repair.
          
   Interim
          Built at regular intervals between maintenance releases and
          receive less testing. Interims should be selected only if
          there is no other suitable release that addresses the
          vulnerability. Interim releases are usually not available for
          customer download via CCO without prior arrangement.
          
   In all cases, customers should exercise caution to be certain the
   devices to be upgraded contain sufficient memory and that current
   hardware and software configurations will continue to be supported
   properly by the new release. If the information is not clear,
   contact the Cisco TAC for assistance as shown in the following
   section.
   
   More information on IOS release names and abbreviations is available
   at http://www.cisco.com/warp/public/620/1.html.
                               
 +===========================================================================+
 | Train | Description of | Availability of Fixed Releases* |
 | | Image or Platform | |
 +===========================================================================+
 | 10.3-based Releases and | | | |
 | Earlier | Rebuild | Interim** | Maintenance |
 +===========================================================================+
 | 10.3 and | | |
 | earlier |All |Not affected |
 +===========================================================================+
 | 11.0-based Releases | Rebuild | Interim** | Maintenance |
 +===========================================================================+
 | | |11.0(22a) | | |
 | 11.0 |Major GD release | | | |
 | |for all platforms |2001-Mar-05 | | |
 +===========================================================================+
 | 11.1-based Releases | Rebuild | Interim** | Maintenance |
 +===========================================================================+
 | | |11.1(24a) | | |
 | 11.1 |Major release for | | | |
 | |all platforms |2001-Mar-05 | | |
 +----------+-------------------+------------+---------------+---------------+
 | |ED release for | | |12.1(7) |
 | 11.1AA |access servers: | | | |
 | |1600, 3200, and | | | |
 | |5200 series. | | |2001-Feb-26 |
 +----------+-------------------+------------+---------------+---------------+
 | |Platform-specific |11.1(36)CA1 | | |
 | 11.1CA |support for 7500, | | | |
 | |7200, 7000, and RSP|2001-Mar-02 | | |
 +----------+-------------------+------------+---------------+---------------+
 | |ISP train: added | | | |
 | |support for FIB, |11.1(36)CC1 | | |
 | 11.1CC |CEF, and NetFlow on| | | |
 | |7500, 7200, 7000, |2001-Mar-02 | | |
 | |and RSP | | | |
 +----------+-------------------+------------+---------------+---------------+
 | |Added support for |12.0(11)ST2 | | |
 | 11.1CT |Tag Switching on | | | |
 | |7500, 7200, 7000, | | | |
 | |and RSP |2001-Feb-26 | | |
 +----------+-------------------+------------+---------------+---------------+
 | | |11.1(28)IA1 | | |
 | 11.1IA |DistributedDirector| | | |
 | |only |2001-Feb-26 | | |
 +===========================================================================+
 | 11.2-based Releases | Rebuild | Interim** | Maintenance |
 +===========================================================================+
 | | |11.2(25a) | | |
 | 11.2 |Major release, | | | |
 | |general deployment |2001-Mar-05 | | |
 +----------+-------------------+------------+---------------+---------------+
 | |Platform-specific | | | |
 | |support for IBM | | |12.1(7) |
 | 11.2BC |networking, CIP, | | | |
 | |and TN3270 on 7500,| | |2001-Feb-26 |
 | |7000, and RSP | | | |
 +----------+-------------------+------------+---------------+---------------+
 | |Early deployment |12.0(15)S1 | | |
 | 11.2GS |release to support | | | |
 | |12000 GSR |2001-Feb-20 | | |
 +----------+-------------------+------------+---------------+---------------+
 | | |11.2(25a)P | | |
 | 11.2P |New platform | | | |
 | |support |2001-Mar-05 | | |
 +----------+-------------------+------------+---------------+---------------+
 | | | | |12.1WC |
 | 11.2SA |Catalyst 2900XL | | | |
 | |switch only | | |2001-Apr-12 |
 +----------+-------------------+------------+---------------+---------------+
 | | | | |12.0(10)W5(18c)|
 | 11.2WA3 |LS1010 ATM switch | | | |
 | | | | |Available |
 +----------+-------------------+------------+---------------+---------------+
 | | |11.2(25a)P | | |
 |11.2(4)XA |Initial release for| | | |
 | |the 1600 and 3600 |2001-Mar-05 | | |
 +----------+-------------------+------------+---------------+---------------+
 | |Initial release for| | | |
 | |the 5300 and |11.2(9)XA1 | | |
 |11.2(9)XA |digital modem | | | |
 | |support for the |Unscheduled | | |
 | |3600 | | | |
 +===========================================================================+
 | 11.3-based Releases | Rebuild | Interim** | Maintenance |
 +===========================================================================+
 | | |11.3(11b) | | |
 | 11.3 |Major release for | | | |
 | |all platforms |2001-Mar-05 | | |
 +----------+-------------------+------------+---------------+---------------+
 | |ED for dial | | | |
 | |platforms and |11.3(11a)AA | | |
 | 11.3AA |access servers: | | | |
 | |5800, 5200, 5300, |2001-Mar-05 | | |
 | |7200 | | | |
 +----------+-------------------+------------+---------------+---------------+
 | |Early deployment |12.1(5)DA1 | | |
 | 11.3DA |train for ISP DSLAM| | | |
 | |6200 platform |2001-Feb-28 | | |
 +----------+-------------------+------------+---------------+---------------+
 | |Early deployment | | | |
 | |train for |12.1(4)DB1 | | |
 | |ISP/Telco/PTT xDSL | | | |
 | 11.3DB |broadband | | | |
 | |concentrator | | | |
 | |platform, (NRP) for|2001-Feb-26 | | |
 | |6400 | | | |
 +----------+-------------------+------------+---------------+---------------+
 | |Short-lived ED | |
 | 11.3HA |release for ISR |Not Vulnerable |
 | |3300 (SONET/SDH | |
 | |router) | |
 +----------+-------------------+------------+---------------+---------------+
 | | |11.3(1)MA8 | | |
 | 11.3MA |MC3810 | | | |
 | |functionality only |Unscheduled | | |
 +----------+-------------------+------------+---------------+---------------+
 | |Voice over IP, |12.1(7) | | |
 | 11.3NA |media convergence, | | | |
 | |various platforms |2001-Mar-05 | | |
 +----------+-------------------+------------+---------------+---------------+
 | |Early deployment |11.3(11b)T1 | | |
 | 11.3T |major release, | | | |
 | |feature-rich for | | | |
 | |early adopters |2001-Mar-05 | | |
 +----------+-------------------+------------+---------------+---------------+
 | |Multilayer | | | |
 | |Switching and | | |12.0(14)W5(20) |
 | |Multiprotocol over | | | |
 | 11.3WA4 |ATM functionality | | | |
 | |for Catalyst 5000 | | | |
 | |RSM, 4500, 4700, | | |2001-Feb-28 |
 | |7200, 7500, LS1010 | | | |
 +----------+-------------------+------------+---------------+---------------+
 | | |11.3(11b)T1 | | |
 |11.3(2)XA |Introduction of | | | |
 | |ubr7246 and 2600 |2001-Mar-05 | | |
 +===========================================================================+
 | 12.0-based Releases | Rebuild | Interim** | Maintenance |
 +===========================================================================+
 | |General deployment | |12.0(7.1) |12.0(16) |
 | 12.0 |release for all | | | |
 | |platforms | |Available |2001-Feb-20 |
 +----------+-------------------+------------+---------------+---------------+
 | | | |12.0(7.1)T | |
 | 12.0DA |xDSL support: 6100,| | | |
 | |6200 | |Available | |
 +----------+-------------------+------------+---------------+---------------+
 | |ISP/Telco/PTT xDSL |12.1(4)DB1 | | |
 | 12.0DB |broadband | | | |
 | |concentrator | | | |
 | |platforms |2001-Feb-26 | | |
 +----------+-------------------+------------+---------------+---------------+
 | | |12.1(4)DC2 | | |
 | 12.0DC |6400 Access | | | |
 | |Concentrator |2001-Feb-26 | | |
 +----------+-------------------+------------+---------------+---------------+
 | | |12.0(15)S1 | | |
 | 12.0S |Core/ISP support: | | | |
 | |GSR, RSP, c7200 |2001-Feb-20 | | |
 +----------+-------------------+------------+---------------+---------------+
 | | |12.0(15)SC1 | | |
 | 12.0SC |Cable/broadband | | | |
 | |ISP: ubr7200 |2001-Feb-26 | | |
 +----------+-------------------+------------+---------------+---------------+
 | | |12.0(14)SL1 | | |
 | 12.0SL |10000 ESR: c10k | | | |
 | | |2001-Feb-26 | | |
 +----------+-------------------+------------+---------------+---------------+
 | |General deployment |12.0(11)ST2 | | |
 | 12.0ST |release for all | | | |
 | |platforms |2001-Feb-26 | | |
 +----------+-------------------+------------+---------------+---------------+
 | | |12.1(5c)E8 | | |
 | 12.0SX |Early Deployment | | | |
 | |(ED) |2001-Feb-26 | | |
 +----------+-------------------+------------+---------------+---------------+
 | |Early | | | |
 | |Deployment(ED): | | |12.1(7) |
 | 12.0T |VPN, Distributed | | | |
 | |Director, various | | |2001-Feb-26 |
 | |platforms | | | |
 +----------+-------------------+------------+---------------+---------------+
 | |cat8510c, cat8540c,| | | |
 | |ls1010, cat8510m, | |12.0(10)W5(18c)|12.0(14)W5(20) |
 | |cat8540m, c5atm, | | | |
 | |c5atm, c3620, | | | |
 | |c3640, c4500, | | | |
 | 12.0W5 |c5rsfc, c5rsm, | |Available |2001-Feb-28 |
 | |c7200, rsp, | | | |
 | |cat2948g, cat4232 | | | |
 | +-------------------+------------+---------------+---------------+
 | | | |12.0(10)W5(18d)|12.0(14)W5(20) |
 | |c6msm | | | |
 | | | |Available |2001-Feb-28 |
 +----------+-------------------+------------+---------------+---------------+
 | |General deployment | | |12.0(13)WT6(1) |
 | 12.0WT |release for all | | | |
 | |platforms | | |2001-Feb-20 |
 +----------+-------------------+------------+---------------+---------------+
 | |Early Deployment | | |12.1(7) |
 | 12.0XA |(ED): limited | | | |
 | |platforms | | |2001-Feb-26 |
 +----------+-------------------+------------+---------------+---------------+
 | | | | |12.1(7) |
 | 12.0XB |Short-lived early | | | |
 | |deployment release | | |2001-Feb-26 |
 +----------+-------------------+------------+---------------+---------------+
 | |Early Deployment | | |12.1(7) |
 | 12.0XC |(ED): limited | | | |
 | |platforms | | |2001-Feb-26 |
 +----------+-------------------+------------+---------------+---------------+
 | |Early Deployment | | |12.1(7) |
 | 12.0XD |(ED): limited | | | |
 | |platforms | | |2001-Feb-26 |
 +----------+-------------------+------------+---------------+---------------+
 | |Early Deployment |12.1(5c)E8 | | |
 | 12.0XE |(ED): limited | | | |
 | |platforms |2001-Feb-26 | | |
 +----------+-------------------+------------+---------------+---------------+
 | |Early Deployment | | |12.1(7) |
 | 12.0XF |(ED): limited | | | |
 | |platforms | | |2001-Feb-26 |
 +----------+-------------------+------------+---------------+---------------+
 | |Early Deployment | | |12.1(7) |
 | 12.0XG |(ED): limited | | | |
 | |platforms | | |2001-Feb-26 |
 +----------+-------------------+------------+---------------+---------------+
 | |Early Deployment |12.0(4)XH5 | | |
 | 12.0XH |(ED): limited | | | |
 | |platforms |2001-Mar-05 | | |
 +----------+-------------------+------------+---------------+---------------+
 | |Early Deployment | | |12.1(7) |
 | 12.0XI |(ED): limited | | | |
 | |platforms | | |2001-Feb-26 |
 +----------+-------------------+------------+---------------+---------------+
 | |Early Deployment | | |12.1(7) |
 | 12.0XJ |(ED): limited | | | |
 | |platforms | | |2001-Feb-26 |
 +----------+-------------------+------------+---------------+---------------+
 | |Early Deployment |12.0(7)XK4 | | |
 | 12.0XK |(ED): limited | | | |
 | |platforms |Unscheduled | | |
 +----------+-------------------+------------+---------------+---------------+
 | |Early Deployment |12.0(4)XH5 | | |
 | 12.0XL |(ED): limited | | | |
 | |platforms |2001-Mar-05 | | |
 +----------+-------------------+------------+---------------+---------------+
 | | | | |12.1(7) |
 | 12.0XM |Short-lived early | | | |
 | |deployment release | | |2001-Feb-26 |
 +----------+-------------------+------------+---------------+---------------+
 | |Early Deployment | | | |
 | 12.0XN |(ED): limited | | | |
 | |platforms | | | |
 +----------+-------------------+------------+---------------+---------------+
 | |Early Deployment | | |12.1WC |
 | 12.0XP |(ED): limited | | | |
 | |platforms | | |2001-Apr-12 |
 +----------+-------------------+------------+---------------+---------------+
 | | | | |12.1(7) |
 | 12.0XQ |Short-lived early | | | |
 | |deployment release | | |2001-Feb-26 |
 +----------+-------------------+------------+---------------+---------------+
 | | |12.1(5)T5 | | |
 | 12.0XR |Short-lived early | | | |
 | |deployment release |2001-Mar-05 | | |
 +----------+-------------------+------------+---------------+---------------+
 | | |12.1(5c)E8 | | |
 | 12.0XS |Short-lived early | | | |
 | |deployment release |2001-Feb-26 | | |
 +----------+-------------------+------------+---------------+---------------+
 | |Early Deployment | | |12.1WC |
 | 12.0XU |(ED): limited | | | |
 | |platforms | | |2001-Apr-12 |
 +----------+-------------------+------------+---------------+---------------+
 | | |12.1(5)T5 | | |
 | 12.0XV |Short-lived early | | | |
 | |deployment release |2001-Mar-05 | | |
 +===========================================================================+
 |12.1-based and Later Releases | Rebuild | Interim** | Maintenance |
 +===========================================================================+
 | All 12.1 | | |
 | Releases |Various platforms |Not Vulnerable |
 +===========================================================================+
 | 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 with service
   contracts may upgrade to any software release. Customers without
   contracts may upgrade only within a single row of the table above,
   except that any available fixed software release will be provided to
   any customer who can use it and for whom the standard fixed software
   release is not yet available. Customers may install only the feature
   sets they have purchased.
   
   Note that not all fixed software may be available as of the release
   date of this notice.
   
   Customers with contracts should obtain upgraded software through
   their regular update channels. For most customers, this means that
   upgrades should be obtained via Cisco's Software Center at
   http://www.cisco.com/.
   
   Customers without contracts or warranty should get their upgrades by
   contacting the Cisco Technical Assistance Center (TAC) as shown
   below:
     * (800) 553-2447 (toll-free in North America)
     * +1 408 526 7209 (toll call from anywhere in the world)
     * e-mail: taccisco.com
       
   See http://www.cisco.com/warp/public/687/Directory/DirTAC.shtml for
   additional TAC contact information, including instructions and
   e-mail addresses for use in various languages.
   
   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
   "psirtcisco.com" or "security-alertcisco.com" for software
   upgrades; faster results will be obtained by contacting the TAC
   directly.
   
Workarounds

   Several workarounds are available based on customer needs,
   equipment, and software features. The usefulness and practicality of
   each workaround depends on the IOS release running on the device and
   many variables in the customer's environment. Customers are urged to
   consider each of the following alternatives carefully before
   deploying. These workarounds are only needed if it is not possible
   to upgrade to an unaffected release of IOS software.

    A. Default workaround for use with releases for which no other
       workarounds are effective:

         1. Applying access lists to all the interfaces of the
            vulnerable device blocking SNMP from all hosts but those
            authorized to manage the devices.

         2. Blocking SNMP access at the edge of the network to prevent
            undesirable SNMP traffic from entering the network
            containing the vulnerable device.

       Access lists should be deployed with careful consideration of
       the possible effects on network operation and performance. Also
       note that authentication based on an IP source address is weak,
       so the preceding method will not protect against certain types
       of attacks in which the IP source address has been spoofed.
       Further information can be found in the Cisco document
       "Improving Security on Cisco Routers", available at
       http://www.cisco.com/warp/public/707/21.html

    B. For affected releases based on IOS 11.1:

         1. Remove the view so that the ILMI community cannot be
            reached:

                no snmp-server view *ilmi

         2. This configuration will not survive a system reload. The
            command must be re-entered after every restart of the
            system.

    C. For affected releases of IOS 11.2 through 11.3(8) NOT REQUIRING
       ATM:

       In this affected range of releases, the ILMI community string
       can be modified or deleted. However, the changes will not
       persist through a reboot of the device. These instructions must
       be re-applied following every system reload of the affected
       device:

         1. Expose the undocumented ILMI community string so it can be
            modified:

                snmp-server community ILMI RW

            The preceding command may cause an error that can be safely
            ignored.

         2. Disable read-write capability for the same community:

                no snmp-server community ILMI RW

            If an error is displayed, then this workaround cannot be
            applied to the device. Use the default workarounds
            presented in the first item above.

         3. Since this configuration will not survive a system reload,
            the command must be re-entered after every restart of the
            system.

       If the command in item 2 above did not generate an error and ATM
       is not needed on this device, then this workaround is complete.

    D. For affected releases of IOS 11.2 through 11.3(8) THAT REQUIRE
       ATM:

       This workaround will allow ILMI to continue to function for ATM
       while constraining who may reconfigure the device by way of the
       ILMI community string:

         1. Create a simple ACL to deny access using the following
            command. If "66" is already in use, choose a different
            two-digit number:

                access-list 66 deny any

         2. Apply it generally to the ILMI community to restrict its
            view:

                snmp community ILMI view *ilmi RW 66

            An error will be reported if the *ilmi view doesn't exist.
            If that occurs, then use the following command to
            explicitly restrict the ILMI view:

                snmp community ILMI RW 66

            If the preceding command produces persistent errors, then
            this workaround cannot be applied to this device. Use the
            default workarounds presented in the first item above.

    E. For affected releases of IOS 11.3(9) through 12.0(2)T NOT
       REQUIRING ATM:

       All versions of IOS in this range will accept this workaround,
       and the change will remain in place after a system reload.

         1. Expose the undocumented ILMI community string so it can be
            modified:

                snmp-server community ILMI RW

            The preceding command may cause an error that can be safely
            ignored.

         2. Disable read-write capability for the same community:

                no snmp-server community ILMI RW

            If an error is displayed, then this workaround cannot be
            applied to the device. Stop this procedure and use the
            default workarounds presented in the first item above.

    F. For affected releases of IOS 11.3(9) through 12.0(2)T THAT
       REQUIRE ATM:

       This workaround will allow ILMI to continue to function for ATM
       while constraining who may reconfigure the device by way of the
       ILMI community string:

         1. Create a simple ACL to deny access using the following
            command. If "66" is already in use, choose a different
            two-digit number:

                access-list 66 deny any

         2. Apply it generally to the ILMI community to restrict its
            view:

                snmp community ILMI view *ilmi RW 66

            An error will be reported if the *ilmi view doesn't exist.
            If that occurs, then use the following command to
            explicitly restrict the ILMI view:

              snmp community ILMI RW 66

            If the preceding command produces persistent errors, then
            this workaround cannot be applied to this device. Use the
            default workaround presented in the first item above.

    G. For affected releases of IOS 12.0(3)T and later:
       These releases of IOS include support for Simple Network
       Management Protocol version 3 (SNMPv3), which is required for
       this workaround.

         1. Confirm the presence of SNMPv3 support by asking the
            console CLI (command-line interpreter) for assistance with
            options to complete the snmp-server command. Enter config
            mode, enter the command shown below, and note the expected
            response:

              snmp-server user test test ?

              remote Specify a remote SNMP entity to which the user belongs
              v1 user using the v1 security model
              v2c user using the v2c security model
              v3 user using the v3 security model

            If the preceding command did not produce the expected
            results, then SNMPv3 is not supported in the release and
            this workaround cannot be applied. Stop this procedure and
            consider applying the default workaround presented above in
            the first item.

            Otherwise, if the device responded as expected, continue
            with the following explanation and instructions.

       In these IOS releases (12.0(3)T and later), ILMI packets are
       processed by the SNMP engine in the same manner as ordinary IP
       SNMP packets. An access control list or a view applied to the
       ILMI community string will be processed whether the transport is
       ILMI or IP. However, the only types of access control lists that
       can be applied to a community string are via IP access-list
       statements, which when applied, block ALL non-IP packets,
       including ILMI packets. Modifying or deleting the *ilmi view
       will also affect the packets transported by ILMI, so workarounds
       that change the view are equally ineffective at permitting ILMI
       while denying SNMP. In this range of releases, it is not
       possible to apply a workaround that denies IP SNMP packets that
       does not also deny ILMI SNMP packets.

    H. For affected releases of IOS 12.0(3)T and later NOT REQUIRING
       ATM:

         1. Expose the undocumented ILMI community string so it can be
            modified:

              snmp-server community ILMI RW

            The preceding command may cause an error that can be safely
            ignored.

         2. Disable read-write capability for the same community:

              no snmp-server community ILMI RW

            If an error is displayed, then this workaround cannot be
            applied to the device. Stop this procedure and consider
            using the default workaround.

    I. For affected releases of IOS 12.0(3)T and later THAT REQUIRE
       ATM:

       NOTE: This section also applies to 12.0-based ATM switch
       software such as for the LS1010 and the 8500 series.

       The only effective workaround for systems in this category is
       the default workaround:

         1. Applying access lists to all the interfaces of the
            vulnerable device blocking SNMP from all hosts but those
            authorized to manage the devices.

         2. Blocking SNMP access at the edge of the network to prevent
            undesirable SNMP traffic from entering the network
            containing the vulnerable device.

       Access lists should be deployed with careful consideration of
       the possible effects on network operation and performance. Also
       note that authentication based on an IP source address is weak,
       so the preceding method will not protect against certain types
       of attacks in which the IP source address has been spoofed.
       In this range of releases it is not possible to block IP SNMP
       packets while permitting ILMI SNMP packets. The alternative
       workarounds presented previously will almost certainly cause a
       failure of ATM ILMI communications resulting in a loss of ATM
       connectivity, either immediately upon configuration, or
       unexpectedly at some later time. Either use the default
       workaround or upgrade to fixed software.
       
Exploitation and Public Announcements

   This vulnerability is known to the engineering staff of several
   Cisco customers. Cisco considers it known to the public prior to the
   publication of this notice.
   
   Cisco is aware of one recent incident involving the unauthorized
   modification of a router that appears to have resulted from this
   vulnerability. However, it may have been the unintended side-effect
   of a test of the vulnerability.
   
   Cisco is not aware of any available tools specifically designed to
   make use of this vulnerability. However, various off-the-shelf
   network management programs could easily be used to test for this
   vulnerability and to exploit it. Certain widely-available programs
   known to the cracker community could be modified by any reasonably
   competent programmer to automate the abuse of this vulnerability.
   
   Cisco is not aware of any general public discussion of this
   vulnerability other than the exceptions previously noted.
   
Status of This Notice: INTERIM

   This is an interim security advisory. Cisco anticipates issuing
   updated versions of this notice at irregular intervals as there are
   material changes in the facts, and will continue to update this
   notice as necessary. The reader is warned that this notice may
   contain inaccurate or incomplete information. 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
   anticipates issuing monthly updates of this notice until it reaches
   FINAL status.
   
   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.
   
Distribution

   This notice will be posted at
   http://www.cisco.com/warp/public/707/ios-snmp-ilmi-vuln-pub.shtml .
   
   In addition to Worldwide Web posting, a text version of this notice
   will be clear-signed with the Cisco PSIRT PGP key and will be posted
   to the following e-mail and Usenet news recipients:

     * cust-security-announcecisco.com

     * bugtraqsecurityfocus.com

     * firewallslists.gnac.com

     * first-teamsfirst.org (including CERT/CC)

     * ciscospot.colorado.edu

     * cisco-nsppuck.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 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 2001-Feb-27 First interim public version
   
Cisco Product Security Incident Procedures

   Instructions for reporting product security vulnerabilities in Cisco
   products, obtaining assistance with customer security incidents, and
   registering to receive security information from Cisco can be found
   at http://www.cisco.com/warp/public/707/sec_incident_response.shtml
   , including instructions for press inquiries regarding Cisco
   Security Advisories.
     _______________________________________________________________
   
   Copyright 2001 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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