[apops] Cisco Security Advisory: Crafted Packet Causes Reload onCisco Ro

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  • Subject: [apops] Cisco Security Advisory: Crafted Packet Causes Reload onCisco Routers
  • From: Cisco Systems Product Security Incident Response Team <psirt at cisco dot com>
  • Date: Wed, 26 Jan 2005 17:00:00 +0100
  • Cc: psirt at cisco dot com
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      Cisco Security Advisory: Crafted Packet Causes Reload on Cisco Routers
      
      Revision 1.0
      
      For Public Release 2005 January 26 1600 (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
      =======
      
      Cisco Routers running Internetwork Operating System (IOS) that supports Multi
      Protocol Label Switching (MPLS) are vulnerable to a Denial of Service (DoS)
      attack on MPLS disabled interfaces. A system that supports MPLS is vulnerable
      even if that system is not configured for MPLS.
      
      The vulnerability is only present in Cisco IOS release trains based on 12.1T,
      12.2, 12.2T, 12.3 and 12.3T. Releases based on 12.1 mainline, 12.1E and all
      releases prior to 12.1 are not vulnerable.
      
      Cisco has made free software available to address this vulnerability.
      
      There are workarounds available to mitigate the effects.
      
      This issue is tracked by CERT/CC VU#583638.
      
      This advisory is available at 
      http://www.cisco.com/warp/public/707/cisco-sa-20050126-les.shtml.
      
      Affected Products
      =================
      
      Vulnerable Products
      
      Only the following products running a vulnerable version of IOS that support
      MPLS are affected.
      
        * 2600 and 2800 series routers
        * 3600, 3700 and 3800 series routers
        * 4500 and 4700 series routers
        * 5300, 5350 and 5400 series Access Servers
      
      Products that are not listed above are not affected.
      
      MPLS is not supported in IP and IP Plus feature sets. Therefore, products
      running an IOS version with an IP or IP Plus feature set are not vulnerable.
      
      An attack can only be launched at systems that are not configured for MPLS
      Traffic Engineering and on the interfaces where MPLS is not enabled. MPLS
      enabled interfaces can be determined by the show mpls interfaces command.
      
      An unaffacted system where MPLS is not supported will give an output similar to
      the following.
      
          Router#show mpls interfaces
                       ^
            % Invalid input detected at '^' marker.
      
          Router#
      
      
      MPLS can be enabled in different ways on a router. In the below output, a
      router is shown that has MPLS enabled for IP on interface Ethernet0/0.
      
            Router#show mpls interfaces
            Interface              IP            Tunnel   Operational
            Ethernet0/0            Yes (tdp)     No       Yes
            Router#
      
      
      When MPLS for IP is enabled on an interface, the router is immune to the
      attacks coming from that interface but vulnerable to the attacks coming from
      other interfaces. Enabling MPLS for IP on all interfaces of the router will
      make the router immune to attacks coming from any interface. An interface that
      has MPLS for IP enabled will have mpls ip or tag-switching ip command in the
      interface configuration.
      
      MPLS Traffic Engineering (TE) provides a better protection against this
      vulnerability. If MPLS TE is enabled globally, the router will be immune to the
      attacks coming from any interface. A router that has MPLS TE enabled will have
      mpls traffic-eng tunnels command in the show running-config output.
      
      Products Confirmed Not Vulnerable
      
        * Products that are not running Cisco IOS are not vulnerable.
        * Products running Cisco IOS versions 12.0 and earlier and 12.1 mainline are
          not vulnerable.
        * Products that are not mentioned in the Affected Products section are not
          vulnerable (including but not limited to Cisco 7200, 7500, 12000 series and
          Catalyst systems).
      
      No other Cisco products are currently known to be affected by these
      vulnerabilities.
      
      Details
      =======
      
      Multi Protocol Label Switching (MPLS) is a vendor-independent protocol that
      integrates layer-2 (as defined in the Open System Interconnection Reference
      Model) information into layer-3. More information on MPLS can be found at http:
      //www.cisco.com/warp/public/732/Tech/mpls.
      
      A vulnerability exists in the processing of an MPLS packet that is received on
      an interface where MPLS is disabled. A router that is configured for MPLS
      Traffic Engineering is immune to attacks coming from any interface.
      
      A Cisco device receiving a crafted packet on an MPLS disabled interface will
      reset and may take several minutes to become fully functional. This
      vulnerability may be exploited repeatedly resulting in an extended DoS attack.
      This issue is documented in bugs ID CSCeb56909 ( registered customers only) and
      CSCec86420 ( registered customers only) .
      
      Such crafted packets can only be sent from the local network segment.
      
      Impact
      ======
      
      Successful exploitation of this vulnerability could result in a reload of the
      device. Repeated exploitation could result in a sustained DoS attack.
      
      Software Versions and Fixes
      
      +---------------------------------------------+
      |  Major Release  | Availability of Repaired  |
      |                 |         Releases          |
      |-----------------+---------------------------|
      | Affected        |          |             |  |
      | 12.1-Based      | Rebuild  | Maintenance |  |
      | Release         |          |             |  |
      |-----------------+------------------------+--|
      | 12.1DB          | Migrate to 12.3(4)T or |  |
      |                 | later                  |  |
      |-----------------+------------------------+--|
      | 12.1DC          | Migrate to 12.3(4)T or |  |
      |                 | later                  |  |
      |-----------------+------------------------+--|
      | 12.1T           | Migrate to 12.2 or     |  |
      |                 | later                  |  |
      |-----------------+------------------------+--|
      | 12.1XG          | Migrate to 12.3 or     |  |
      |                 | later                  |  |
      |-----------------+------------------------+--|
      | 12.1XI          | Migrate to 12.2 or     |  |
      |                 | later                  |  |
      |-----------------+------------------------+--|
      | 12.1XJ          | Migrate to 12.3 or     |  |
      |                 | later                  |  |
      |-----------------+------------------------+--|
      | 12.1XL          | Migrate to 12.3 or     |  |
      |                 | later                  |  |
      |-----------------+------------------------+--|
      | 12.1XM          | Migrate to 12.3 or     |  |
      |                 | later                  |  |
      |-----------------+------------------------+--|
      | 12.1XP          | Migrate to 12.3 or     |  |
      |                 | later                  |  |
      |-----------------+------------------------+--|
      | 12.1XQ          | Migrate to 12.3 or     |  |
      |                 | later                  |  |
      |-----------------+------------------------+--|
      | 12.1XR          | Migrate to 12.3 or     |  |
      |                 | later                  |  |
      |-----------------+------------------------+--|
      | 12.1XT          | Migrate to 12.3 or     |  |
      |                 | later                  |  |
      |-----------------+------------------------+--|
      | 12.1XU          | Migrate to 12.3 or     |  |
      |                 | later                  |  |
      |-----------------+------------------------+--|
      | 12.1XV          | Migrate to 12.3 or     |  |
      |                 | later                  |  |
      |-----------------+------------------------+--|
      | 12.1YA          | Migrate to 12.3 or     |  |
      |                 | later                  |  |
      |-----------------+------------------------+--|
      | 12.1YB          | Migrate to 12.3 or     |  |
      |                 | later                  |  |
      |-----------------+------------------------+--|
      | 12.1YC          | Migrate to 12.3 or     |  |
      |                 | later                  |  |
      |-----------------+------------------------+--|
      | 12.1YD          | Migrate to 12.3 or     |  |
      |                 | later                  |  |
      |-----------------+------------------------+--|
      | 12.1YE          | Migrate to 12.3 or     |  |
      |                 | later                  |  |
      |-----------------+------------------------+--|
      | 12.1YF          | Migrate to 12.3 or     |  |
      |                 | later                  |  |
      |-----------------+------------------------+--|
      | 12.1YH          | Migrate to 12.3 or     |  |
      |                 | later                  |  |
      |-----------------+------------------------+--|
      | 12.1YI          | Migrate to 12.3 or     |  |
      |                 | later                  |  |
      |-----------------+------------------------+--|
      | Affected        |          |             |  |
      | 12.2-Based      | Rebuild  | Maintenance |  |
      | Release         |          |             |  |
      |-----------------+----------+-------------+--|
      |                 | 12.2     |             |  |
      |                 | (10g)    |             |  |
      |                 |----------+-------------+--|
      |                 | 12.2     |             |  |
      |                 | (13e)    |             |  |
      |                 |----------+-------------+--|
      |                 | 12.2     |             |  |
      |                 | (16f)    |             |  |
      |                 |----------+-------------+--|
      | 12.2            | 12.2     |             |  |
      |                 | (17d)    |             |  |
      |                 |----------+-------------+--|
      |                 | 12.2     |             |  |
      |                 | (19b)    |             |  |
      |                 |----------+-------------+--|
      |                 | 12.2     |             |  |
      |                 | (21a)    |             |  |
      |                 |----------+-------------+--|
      |                 |          | 12.2(23)    |  |
      |-----------------+------------------------+--|
      |                 | 12.2(2)B through 12.2  |  |
      |                 | (4)B7, Migrate to 12.3 |  |
      |                 | or later               |  |
      |12.2B            |------------------------+--|
      |                 | 12.2(4)B8 and forward, |  |
      |                 | Migrate to 12.3(4)T or |  |
      |                 | later                  |  |
      |-----------------+------------------------+--|
      | 12.2BC          | 12.2(15) |             |  |
      |                 | BC2      |             |  |
      |-----------------+------------------------+--|
      | 12.2BW          | Migrate to 12.3 or     |  |
      |                 | later                  |  |
      |-----------------+------------------------+--|
      | 12.2BX          | Migrate to 12.3(7)XI1  |  |
      |                 | or later               |  |
      |-----------------+------------------------+--|
      | 12.BY           | Migrate to 12.3(4)T or |  |
      |                 | later                  |  |
      |-----------------+------------------------+--|
      | 12.2BZ          | Migrate to 12.3(7)XI1  |  |
      |                 | or later               |  |
      |-----------------+------------------------+--|
      | 12.2CX          | Migrate to 12.2(15)BC2 |  |
      |-----------------+------------------------+--|
      | 12.2CY          | Migrate to 12.2(15)BC2 |  |
      |-----------------+------------------------+--|
      | 12.2CZ          | 12.2(15)CZ             |  |
      |-----------------+------------------------+--|
      | 12.2DA          | 12.2(12) |             |  |
      |                 | DA6      |             |  |
      |-----------------+------------------------+--|
      | 12.2DD          | Migrate to 12.3(4)T or |  |
      |                 | later                  |  |
      |-----------------+------------------------+--|
      | 12.2DX          | Migrate to 12.3(4)T or |  |
      |                 | later                  |  |
      |-----------------+------------------------+--|
      | 12.2EW          |          | 12.2(18)EW  |  |
      |-----------------+----------+-------------+--|
      | 12.2EWA         |          | 12.2(20)EWA |  |
      |-----------------+----------+-------------+--|
      | 12.2JA          |          | 12.2(15)JA  |  |
      |-----------------+----------+-------------+--|
      | 12.2JK          |          | 12.2(15)JK  |  |
      |-----------------+------------------------+--|
      | 12.2MB          | Migrate to 12.2(19)SW  |  |
      |-----------------+------------------------+--|
      | 12.2MC          | Migrate to 12.3(11)T   |  |
      |-----------------+------------------------+--|
      | 12.2MX          | Migrate to 12.3(8)T or |  |
      |                 | later                  |  |
      |-----------------+------------------------+--|
      |                 | 12.2(14) |             |  |
      | 12.2S           | S10      |             |  |
      |                 |----------+-------------+--|
      |                 |          | 12.2(18)S   |  |
      |-----------------+----------+-------------+--|
      | 12.2SU          |          | 12.2(14)SU  |  |
      |-----------------+----------+-------------+--|
      | 12.2SW          |          | 12.2(19)SW  |  |
      |-----------------+------------------------+--|
      | 12.2SX          | Migrate to 12.2(17d)   |  |
      |                 | SXB or later           |  |
      |-----------------+------------------------+--|
      | 12.2SXA         | Migrate to 12.2(17d)   |  |
      |                 | SXB or later           |  |
      |-----------------+------------------------+--|
      | 12.2SXB         |          | 12.2(17d)   |  |
      |                 |          | SXB         |  |
      |-----------------+----------+-------------+--|
      | 12.2SXD         |          | 12.2(18)SXD |  |
      |-----------------+------------------------+--|
      | 12.2SY          | Migrate to 12.2(17d)   |  |
      |                 | SXB or later           |  |
      |-----------------+------------------------+--|
      | 12.2SZ          | Migrate to 12.2(20)S4  |  |
      |-----------------+------------------------+--|
      | 12.2T           | 12.2(13) |             |  |
      |                 | T14      |             |  |
      |-----------------+------------------------+--|
      | 12.2XA          | Migrate to 12.3 or     |  |
      |                 | later                  |  |
      |-----------------+------------------------+--|
      | 12.2XB          | 12.2(2)  |             |  |
      |                 | XB18     |             |  |
      |-----------------+------------------------+--|
      | 12.2XC          | Migrate to 12.3T or    |  |
      |                 | later                  |  |
      |-----------------+------------------------+--|
      | 12.2XD          | Migrate to 12.3 or     |  |
      |                 | later                  |  |
      |-----------------+------------------------+--|
      | 12.2XE          | Migrate to 12.3 or     |  |
      |                 | later                  |  |
      |-----------------+------------------------+--|
      | 12.2XF          | Migrate to 12.2(15)BC2 |  |
      |-----------------+------------------------+--|
      | 12.2XG          | Migrate to 12.3 or     |  |
      |                 | later                  |  |
      |-----------------+------------------------+--|
      | 12.2XH          | Migrate to 12.3 or     |  |
      |                 | later                  |  |
      |-----------------+------------------------+--|
      | 12.2XI          | Migrate to 12.3 or     |  |
      |                 | later                  |  |
      |-----------------+------------------------+--|
      | 12.2XJ          | Migrate to 12.3 or     |  |
      |                 | later                  |  |
      |-----------------+------------------------+--|
      | 12.2XK          | Migrate to 12.3 or     |  |
      |                 | later                  |  |
      |-----------------+------------------------+--|
      | 12.2XL          | Migrate to 12.3 or     |  |
      |                 | later                  |  |
      |-----------------+------------------------+--|
      | 12.2XM          | Migrate to 12.3 or     |  |
      |                 | later                  |  |
      |-----------------+------------------------+--|
      | 12.2XN          | Migrate to 12.3 or     |  |
      |                 | later                  |  |
      |-----------------+------------------------+--|
      | 12.2XQ          | Migrate to 12.3 or     |  |
      |                 | later                  |  |
      |-----------------+------------------------+--|
      | 12.2XR          |          | 12.2(15)XR  |  |
      |-----------------+------------------------+--|
      | 12.2XS          | Migrate to 12.3 or     |  |
      |                 | later                  |  |
      |-----------------+------------------------+--|
      | 12.2XT          | Migrate to 12.3 or     |  |
      |                 | later                  |  |
      |-----------------+------------------------+--|
      | 12.2XU          | Migrate to 12.3 or     |  |
      |                 | later                  |  |
      |-----------------+------------------------+--|
      | 12.2XV          | No plan.               |  |
      |-----------------+------------------------+--|
      | 12.2XW          | Migrate to 12.3 or     |  |
      |                 | later                  |  |
      |-----------------+------------------------+--|
      | 12.2XZ          | Migrate to 12.3 or     |  |
      |                 | later                  |  |
      |-----------------+------------------------+--|
      | 12.2YA          | 12.2(4)  |             |  |
      |                 | YA8      |             |  |
      |-----------------+------------------------+--|
      | 12.2YB          | Migrate to 12.3 or     |  |
      |                 | later                  |  |
      |-----------------+------------------------+--|
      | 12.2YC          | Migrate to 12.3 or     |  |
      |                 | later                  |  |
      |-----------------+------------------------+--|
      | 12.2YD          | Migrate to 12.3(8)T or |  |
      |                 | later                  |  |
      |-----------------+------------------------+--|
      | 12.2YE          | Migrate to 12.2(18)S   |  |
      |                 | or later               |  |
      |-----------------+------------------------+--|
      | 12.2YF          | Migrate to 12.3 or     |  |
      |                 | later                  |  |
      |-----------------+------------------------+--|
      | 12.2YG          | Migrate to 12.3 or     |  |
      |                 | later                  |  |
      |-----------------+------------------------+--|
      | 12.2YH          | Migrate to 12.3 or     |  |
      |                 | later                  |  |
      |-----------------+------------------------+--|
      | 12.2YJ          | Migrate to 12.3 or     |  |
      |                 | later                  |  |
      |-----------------+------------------------+--|
      | 12.2YL          | Migrate to 12.3T or    |  |
      |                 | later                  |  |
      |-----------------+------------------------+--|
      | 12.2YM          | Migrate to 12.3T or    |  |
      |                 | later                  |  |
      |-----------------+------------------------+--|
      | 12.2YN          | Migrate to 12.3T or    |  |
      |                 | later                  |  |
      |-----------------+------------------------+--|
      | 12.2YO          | Migrate to 12.2(17d)   |  |
      |                 | SXB or later           |  |
      |-----------------+------------------------+--|
      | 12.2YQ          | Migrate to 12.3(4)T or |  |
      |                 | later                  |  |
      |-----------------+------------------------+--|
      | 12.2YR          | Migrate to 12.3(4)T or |  |
      |                 | later                  |  |
      |-----------------+------------------------+--|
      | 12.2YS          | Migrate to 12.3T or    |  |
      |                 | later                  |  |
      |-----------------+------------------------+--|
      | 12.2YU          | Migrate to 12.3(2)T or |  |
      |                 | later                  |  |
      |-----------------+------------------------+--|
      | 12.2YV          | Migrate to 12.3(4)T or |  |
      |                 | later                  |  |
      |-----------------+------------------------+--|
      | 12.2YW          | Migrate to 12.3(2)T or |  |
      |                 | later                  |  |
      |-----------------+------------------------+--|
      | 12.2YX          | Migrate to 12.2(14)SU  |  |
      |-----------------+------------------------+--|
      | 12.2YZ          | Migrate to 12.2(20)S4  |  |
      |-----------------+------------------------+--|
      | 12.2ZB          | Migrate to 12.3T or    |  |
      |                 | later                  |  |
      |-----------------+------------------------+--|
      | 12.2ZC          | Migrate to 12.3T or    |  |
      |                 | later                  |  |
      |-----------------+------------------------+--|
      | 12.2ZD          | Migrate to 12.3 or     |  |
      |                 | later                  |  |
      |-----------------+------------------------+--|
      | 12.2ZE          | Migrate to 12.3 or     |  |
      |                 | later                  |  |
      |-----------------+------------------------+--|
      | 12.2ZF          | Migrate to 12.3(4)T or |  |
      |                 | later                  |  |
      |-----------------+------------------------+--|
      | 12.2ZG          | Migrate to 12.3(4)T or |  |
      |                 | later                  |  |
      |-----------------+------------------------+--|
      | 12.2ZH          | Migrate to 12.3(4)T or |  |
      |                 | later                  |  |
      |-----------------+------------------------+--|
      | 12.2ZI          | Migrate to 12.2(18)S   |  |
      |                 | or later               |  |
      |-----------------+------------------------+--|
      | 12.2ZJ          | Migrate to 12.3T or    |  |
      |                 | later                  |  |
      |-----------------+------------------------+--|
      | 12.2ZL          | Migrate to 12.3(7)T or |  |
      |                 | later                  |  |
      |-----------------+------------------------+--|
      | 12.2ZN          | Migrate to 12.3T or    |  |
      |                 | later                  |  |
      |-----------------+------------------------+--|
      | 12.2ZO          | Migrate to 12.3 or     |  |
      |                 | later                  |  |
      |-----------------+------------------------+--|
      | 12.2ZP          | No plan.               |  |
      |-----------------+------------------------+--|
      | Affected        |          |             |  |
      | 12.3-Based      | Rebuild  | Maintenance |  |
      | Release         |          |             |  |
      |-----------------+----------+-------------+--|
      |                 | 12.3(3f) |             |  |
      |12.3             |----------+-------------+--|
      |                 |          | 12.3(5)     |  |
      |-----------------+----------+-------------+--|
      | 12.3B           |          | 12.3(5a)B4  |  |
      |-----------------+----------+-------------+--|
      | 12.3BC          |          | 12.3(9a)BC  |  |
      |-----------------+------------------------+--|
      | 12.3BW          | Migrate to 12.3(5a)B   |  |
      |                 | or later               |  |
      |-----------------+------------------------+--|
      |                 | 12.3(2)  |             |  |
      |                 | T5       |             |  |
      |                 |----------+-------------+--|
      | 12.3T           | 12.3(4)  |             |  |
      |                 | T7       |             |  |
      |                 |----------+-------------+--|
      |                 |          | 12.3(7)T    |  |
      |-----------------+------------------------+--|
      | 12.3XA          | Migrate to 12.3(7)T or |  |
      |                 | later                  |  |
      |-----------------+------------------------+--|
      | 12.3XB          | Migrate to 12.3(8)T or |  |
      |                 | later                  |  |
      |-----------------+------------------------+--|
      |                 | Migrate to 12.3(2)XC3  |  |
      | 12.3XC          | - Availablility date   |  |
      |                 | TBD                    |  |
      |-----------------+------------------------+--|
      | 12.3XD          | 12.3(4)XD              |  |
      |-----------------+------------------------+--|
      | 12.3XE          | 12.3(2)XE1             |  |
      |-----------------+------------------------+--|
      | 12.3XF          | 12.3(2)XF              |  |
      |-----------------+------------------------+--|
      | 12.3XG          | 12.3(4)  |             |  |
      |                 | XG1      |             |  |
      |-----------------+------------------------+--|
      | 12.3XH          | 12.3(4)XH              |  |
      |-----------------+------------------------+--|
      | 12.3XI          | 12.3(7)XI              |  |
      |-----------------+------------------------+--|
      | 12.3XJ          | 12.3(7)XJ              |  |
      |-----------------+------------------------+--|
      | 12.3XK          | 12.3(4)  |             |  |
      |                 | XK1      |             |  |
      |-----------------+------------------------+--|
      | 12.3XL          | 12.3(7)XL              |  |
      |-----------------+------------------------+--|
      | 12.3XM          | 12.3(7)XM              |  |
      |-----------------+------------------------+--|
      | 12.3XN          | 12.3(4)XN              |  |
      |-----------------+------------------------+--|
      | 12.3XQ          | 12.3(4)XQ              |  |
      |-----------------+------------------------+--|
      | 12.3XR          | 12.3(7)XR              |  |
      |-----------------+------------------------+--|
      | 12.3XS          | 12.3(7)XS              |  |
      |-----------------+------------------------+--|
      | 12.3XT          | 12.3(2)XT              |  |
      |-----------------+------------------------+--|
      | 12.3XU          | 12.3(8)XU              |  |
      |-----------------+------------------------+--|
      | 12.3XW          | 12.3(8)XW              |  |
      |-----------------+------------------------+--|
      | 12.3XX          | 12.3(8)XX              |  |
      |-----------------+------------------------+--|
      | 12.3XY          | 12.3(8)XY              |  |
      |-----------------+------------------------+--|
      | 12.3YA          | 12.3(8)YA              |  |
      |-----------------+------------------------+--|
      | 12.3YD          | 12.3(8)YD              |  |
      |-----------------+------------------------+--|
      | 12.3YE          | 12.3(4)YE              |  |
      |-----------------+------------------------+--|
      | 12.3YF          | 12.3(11)YF             |  |
      |-----------------+------------------------+--|
      | 12.3YG          | 12.3(8)YG              |  |
      |-----------------+------------------------+--|
      | 12.3YH          | 12.3(8)YH              |  |
      +---------------------------------------------+
      
      When considering software upgrades, please also consult http://www.cisco.com/en
      /US/products/products_security_advisories_listing.html and any subsequent
      advisories to determine exposure and a complete upgrade solution.
      
      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 Technical Assistance Center
      (TAC) for assistance.
      
      Obtaining Fixed Software
      ========================
      
      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 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 assistance with the upgrade, which should be free of
      charge.
      
      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 at cisco dot com
      
      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 at cisco dot com" or "security-alert at cisco dot com"
      for software upgrades.
      
      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.
      
      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.
      
      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.
      
      Warning: Using this workaround may affect the operation of your network and
      might cause problems. Therefore it is strongly recommended that you do a code
      upgrade if you are affected. It is not recommended that you use the workaround
      as a long term solution.
      
      Enabling MPLS Traffic Engineering (MPLS TE) globally can be used as a
      workaround to mitigate this vulnerability. Since MPLS requires Cisco Express
      Forwarding (CEF) in order to work, CEF needs to be enabled first in order to
      enable MPLS TE.
      
      CEF and MPLS TE can be enabled by the following commands.
      
          Router(config)# ip cef
          Router(config)# mpls traffic-eng tunnels
      
      
      Having MPLS TE enabled will make the router immune to the attacks coming from
      any interface.
      
      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 ADVISORY IS PROVIDED ON AN "AS IS" BASIS AND DOES NOT IMPLY ANY KIND OF
      GUARANTEE OR WARRANTY, INCLUDING THE WARRANTY OF MERCHANTABILITY. YOUR USE OF
      THE INFORMATION ON THE ADVISORY OR MATERIALS LINKED FROM THE ADVISORY IS AT
      YOUR OWN RISK. CISCO RESERVES THE RIGHT TO CHANGE OR UPDATE THIS NOTICE AT ANY
      TIME.
      
      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-20050126-les.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 at cisco dot com
        * first-teams at first dot org (includes CERT/CC)
        * bugtraq at securityfocus dot com
        * vulnwatch at vulnwatch dot org
        * cisco at spot dot colorado dot edu
        * cisco-nsp at puck dot nether dot net
        * full-disclosure at lists dot netsys dot com
        * comp.dcom.sys.cisco at newsgate dot cisco dot com
        * 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 | 2005-January-26 | Initial public |
      | 1.0      |                 | 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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