[apops] Cisco Security Advisory: Cisco IOS Software Border Gateway Proto

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  • Subject: [apops] Cisco Security Advisory: Cisco IOS Software Border Gateway Protocol 4-Byte Autonomous System Number Vulnerabilities
  • From: Cisco Systems Product Security Incident Response Team <psirt at cisco dot com>
  • Date: Wed, 29 Jul 2009 15:00:00 -0000
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      Cisco Security Advisory: Cisco IOS Software Border Gateway Protocol
                               4-Byte Autonomous System Number
                               Vulnerabilities
      
      Advisory ID: cisco-sa-20090729-bgp
      
      http://www.cisco.com/warp/public/707/cisco-sa-20090729-bgp.shtml
      
      Revision: 1.0
      =========
      
      For Public Release 2009 July 29 1600 UTC (GMT)
      
      Summary
      =======
      
      Recent versions of Cisco IOS Software support RFC4893 ("BGP Support
      for Four-octet AS Number Space") and contain two remote denial of
      service (DoS) vulnerabilities when handling specific Border Gateway
      Protocol (BGP) updates.
      
      These vulnerabilities affect only devices running Cisco IOS Software
      with support for four-octet AS number space (here after referred to as
      4-byte AS number) and BGP routing configured.
      
      The first vulnerability could cause an affected device to reload when
      processing a BGP update that contains autonomous system (AS) path
      segments made up of more than one thousand autonomous systems.
      
      The second vulnerability could cause an affected device to reload when
      the affected device processes a malformed BGP update that has been
      crafted to trigger the issue.
      
      Cisco has released free software updates to address these
      vulnerabilities.
      
      No workarounds are available for the first vulnerability.
      
      A workaround is available for the second vulnerability.
      
      This advisory is posted at the following link:
      http://www.cisco.com/warp/public/707/cisco-sa-20090729-bgp.shtml
      
      Affected Products
      =================
      
      Vulnerable Products
      +------------------
      
      These vulnerabilities affect only devices running Cisco IOS and 
      Cisco IOS XE Software (here after both referred to as simply Cisco
      IOS) with support for RFC4893 and that have been configured for 
      BGP routing.
      
      The software table in the section "Software Versions and Fixes" of
      this advisory indicates all affected Cisco IOS Software versions that
      have support for RFC4893 and are affected by this vulnerability.
      
      A Cisco IOS software version that has support for RFC4893 will allow
      configuration of AS numbers using 4 Bytes. The following example
      identifies a Cisco device that has 4 byte AS number support:
      
          Router#configure terminal
          Enter configuration commands, one per line.  End with CNTL/Z.
          Router(config)#router bgp ?
            <1-65535>    Autonomous system number
            <1.0-XX.YY>  4 Octets Autonomous system number
      
          Or:
      
          Router#configure terminal
          Enter configuration commands, one per line.  End with CNTL/Z.
          Router(config)#router bgp ?
            <1-4294967295>  Autonomous system number
            <1.0-XX.YY>     Autonomous system number
      
      The following example identifies a Cisco device that has 2 byte AS
      number support:
      
          Router#configure terminal
          Enter configuration commands, one per line.  End with CNTL/Z.
          Router(config)#router bgp ?
            <1-65535>  Autonomous system number
      
      A router that is running the BGP process will contain a line in the
      configuration that defines the autonomous system number (AS number),
      which can be seen by issuing the command line interface (CLI) command
      "show running-config".
      
      The canonical textual representation of four byte AS Numbers is
      standardized by the IETF through RFC5396 (Textual Representation of
      Autonomous System (AS) Numbers). Two major ways for textual
      representation have been defined as ASDOT and ASPLAIN. Cisco IOS
      routers support both textual representations of AS numbers. For
      further information about textual representation of four byte AS
      numbers in Cisco IOS Software consult the document "Explaining 4-Byte
      Autonomous System (AS) ASPLAIN and ASDOT Notation for Cisco IOS" at
      the following link:
      http://www.cisco.com/en/US/prod/collateral/iosswrel/ps6537/ps6554/ps6599/white_paper_c11_516829.html
         
      Cisco IOS Software with support for RFC4893 is affected by both
      vulnerabilities if BGP routing is configured using either ASPLAIN or
      ASDOT notation.
      
      The following example identifies a Cisco device that is configured
      for BGP using ASPLAIN notation:
      
          router bgp 65536
      
      The following example identifies a Cisco device that is configured
      for BGP using ASDOT notation:
      
          router bgp 1.0
      
      To determine the Cisco IOS Software release that is running on a
      Cisco product, administrators can log in to the device and issue the
      show version command to display the system banner. The system banner
      confirms that the device is running Cisco IOS Software by displaying
      text similar to "Cisco Internetwork Operating System Software" or
      "Cisco IOS Software." The image name displays in parentheses,
      followed by "Version" and the Cisco IOS Software release name. Other
      Cisco devices do not have the show version command or may provide
      different output.
      
      The following example identifies a Cisco product that is running
      Cisco IOS Software Release 12.3(26) with an installed image name of
      C2500-IS-L:
      
          Router#show version
          Cisco Internetwork Operating System Software
          IOS (tm) 2500 Software (C2500-IS-L), Version 12.3(26), RELEASE SOFTWARE (fc2)
          Technical Support: http://www.cisco.com/techsupport
          Copyright (c) 1986-2008 by cisco Systems, Inc.   
          Compiled Mon 17-Mar-08 14:39 by dchih
      
      
          !--- output truncated
      
      
      The following example identifies a Cisco product that is running
      Cisco IOS Software Release 12.4(20)T with an installed image name of
      C1841-ADVENTERPRISEK9-M:
      
          Router#show version
          Cisco IOS Software, 1841 Software (C1841-ADVENTERPRISEK9-M), Version 12.4(20)T, RELEASE SOFTWARE (fc3)
          Technical Support: http://www.cisco.com/techsupport
          Copyright (c) 1986-2008 by Cisco Systems, Inc.
          Compiled Thu 10-Jul-08 20:25 by prod_rel_team
      
      
          !--- output truncated
      
      
      Additional information about Cisco IOS Software release naming
      conventions is available in "White Paper: Cisco IOS Reference Guide"
      at the following link: http://www.cisco.com/warp/public/620/1.html
      
      Products Confirmed Not Vulnerable  
      +--------------------------------
      
      The following Cisco products are confirmed not vulnerable:
      
        * Cisco IOS Software not explicitly mentioned in this Advisory
        * Cisco IOS XR Software
        * Cisco IOS NX-OS
      
      No other Cisco products are currently known to be affected by this
      vulnerability.
      
      Details     
      =======   
      
      RFC4271 has defined an AS number as a two-octet entity in BGP. 
      RFC4893 has defined an AS number as a four-octet entity in BGP.
      
      The first vulnerability could cause an affected device to reload when
      processing a BGP update that contains AS path segments made up of more
      than one thousand autonomous systems. If an affected 4-byte AS number
      BGP speaker receives a BGP update from a 2-byte AS number BGP speaker
      that contains AS path segments made up of more than one thousand
      autonomous systems, the device may crash with memory corruption, and
      the error "%%Software-forced reload" will be displayed.
      
      The following three conditions are required for successful
      exploitation of this vulnerability:
      
        * Affected Cisco IOS Software device is a 4-byte AS number BGP
          speaker
        * BGP peering neighbor is a 2-byte AS number BGP speaker
        * BGP peering neighbor is capable of sending a BGP update with a
          series of greater than one thousand AS numbers
      
          Note: Note: Cisco IOS, Cisco IOS XE, Cisco NX-OS and Cisco IOS XR
          Software, as a 2 byte AS number BGP speaker send BGP updates with
          a maximum of 255 AS numbers.
      
      This vulnerability is documented in Cisco Bug ID CSCsy86021 and has
      been assigned Common Vulnerabilities and Exposures (CVE) ID
      CVE-2009-1168.
      
      The second vulnerability could cause an affected device to reload when
      the affected device processes a malformed BGP update that has been
      crafted to trigger the issue. The following three conditions are
      required for successful exploitation of this vulnerability:
      
        * Affected Cisco IOS Software device is a 4-byte AS number BGP
          speaker
        * BGP peering neighbor is a 2-byte AS number BGP speaker
        * BGP peering neighbor is capable of sending a non-RFC compliant
          crafted BGP update message
      
      This vulnerability is documented in Cisco Bug ID CSCta33973 and has
      been assigned Common Vulnerabilities and Exposures (CVE) ID 
      CVE-2009-2049.
      
      Further information regarding Cisco support for 4-byte AS number is
      available in "Cisco IOS BGP 4-Byte ASN Support" at the following
      link: 
      http://www.cisco.com/en/US/prod/collateral/iosswrel/ps6537/ps6554/ps6599/data_sheet_C78-521821.html
      
      Vulnerability Scoring Details      
      =============================
         
      Cisco has provided scores for the vulnerabilities in this advisory
      based on the Common Vulnerability Scoring System (CVSS). The CVSS
      scoring in this Security Advisory is done in accordance with CVSS
      version 2.0.
      
      CVSS is a standards-based scoring method that conveys vulnerability
      severity and helps determine urgency and priority of response.
      
      Cisco has provided a base and temporal score. Customers can then
      compute environmental scores to assist in determining the impact of
      the vulnerability in individual networks.
      
      Cisco has provided an FAQ to answer additional questions regarding
      CVSS at
      
      http://www.cisco.com/web/about/security/intelligence/cvss-qandas.html
      
      Cisco has also provided a CVSS calculator to help compute the
      environmental impact for individual networks at
      
      http://intellishield.cisco.com/security/alertmanager/cvss
      
      
      CSCsy86021: Cisco IOS Software BGP Long AS-path Vulnerability
      
      CVSS Base Score - 7.1
      
      Access Vector           Network
      Access Complexity       Medium
      Authentication          None
      Confidentiality Impact  None
      Availability Impact     Complete
      
      CVSS Temporal Score - 6.7
      Exploitability          Functional
      Remediation Level       Official-Fix
      Report Confidence       Confirmed
       
         
      CSCta33973: Cisco IOS Software Crafted BGP Update Message Vulnerability
       
      CVSS Base Score - 5.4
      
      Access Vector           Network
      Access Complexity       High
      Authentication          None
      Confidentiality Impact  None
      Availability Impact     Complete
      
      CVSS Temporal Score - 4.5
      Exploitability          Functional
      Remediation Level       Official-Fix
      Report Confidence       Confirmed
         
      Impact
      ======     
         
      Successful exploitation of the vulnerabilities described in this
      document may result in a reload of the device. The issue could result
      in repeated exploitation to cause an extended DoS condition.
         
      Software Versions and Fixes
      ===========================
      
      When considering software upgrades, also consult
      http://www.cisco.com/go/psirt 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) or your contracted
      maintenance provider for assistance.
      
      Each row of the Cisco IOS software table (below) names a Cisco IOS
      release train. If a given release train is vulnerable, then the
      earliest possible releases that contain the fix (along with the
      anticipated date of availability for each, if applicable) are listed
      in the "First Fixed Release" column of the table. The "Recommended
      Release" column indicates the releases which have fixes for all the
      published vulnerabilities at the time of this Advisory. 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. Cisco recommends upgrading to a release equal to or
      later than the release in the "Recommended Releases" column of the
      table.
         
      +-------------------------------------------------------------------+
      |  Major   |             Availability of Repaired Releases          |
      | Release  |                                                        |
      |----------+--------------------------------------------------------|
      | Affected |                                           |Recommended |
      |12.0-Based|           First Fixed Release             |  Release   |
      | Releases |                                           |            |
      |----------+-------------------------------------------+------------|
      |12.0      |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.0DA    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.0DB    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.0DC    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |          |Releases up to and including 12.0(32)S11   |            |
      |          |are not vulnerable; first fixed in         |            |
      |12.0S     |12.0(32)S14;                               |            |
      |          |                                           |            |
      |          |Releases up to and including 12.0(33)S2 are|            |
      |          |not vulnerable; first fixed in 12.0(33)S5  |            |
      |----------+-------------------------------------------+------------|
      |12.0SC    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.0SL    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.0SP    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.0ST    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.0SX    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.0SY    |Releases up to and including 12.0(32)SY7   |12.0(32)SY10|
      |          |are not vulnerable; first fixed in         |            |
      |          |12.0(32)SY9a.                              |            |
      |----------+-------------------------------------------+------------|
      |12.0SZ    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.0T     |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.0W     |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.0WC    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.0WT    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.0WX    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.0XA    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.0XB    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.0XC    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.0XD    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.0XE    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.0XF    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.0XG    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.0XH    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.0XI    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.0XJ    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.0XK    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.0XL    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.0XM    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.0XN    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.0XQ    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.0XR    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.0XS    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.0XT    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.0XV    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.0XW    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      | Affected |                                           |Recommended |
      |12.1-Based|            First Fixed Release            |  Release   |
      | Releases |                                           |            |
      |-------------------------------------------------------------------|
      |             There are no affected 12.1 based releases             |
      |-------------------------------------------------------------------|
      | Affected |                                           |Recommended |
      |12.2-Based|            First Fixed Release            |  Release   |
      | Releases |                                           |            |
      |----------+-------------------------------------------+------------|
      |12.2      |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2B     |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2BC    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2BW    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2BX    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2BY    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2BZ    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2CX    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2CY    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2CZ    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2DA    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2DD    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2DX    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2EW    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2EWA   |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2EX    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2EY    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2EZ    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2FX    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2FY    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2FZ    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2IRA   |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2IRB   |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2IRC   |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2IXA   |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2IXB   |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2IXC   |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2IXD   |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2IXE   |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2IXF   |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2IXG   |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2IXH   |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2JA    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2JK    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2MB    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2MC    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2S     |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2SB    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2SBC   |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2SCA   |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2SCB   |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2SE    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2SEA   |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2SEB   |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2SEC   |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2SED   |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2SEE   |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2SEF   |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2SEG   |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2SG    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2SGA   |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2SL    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2SM    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2SO    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2SQ    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2SRA   |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2SRB   |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2SRC   |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2SRD   |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2STE   |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2SU    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2SV    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2SVA   |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2SVC   |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2SVD   |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2SVE   |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2SW    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2SX    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2SXA   |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2SXB   |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2SXD   |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2SXE   |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2SXF   |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2SXH   |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |          |Releases up to and including 12.2(33)SXI   |            |
      |12.2SXI   |are not vulnerable; CSCsy86021 first fixed |            |
      |          |in 12.2(33)SXI2; CSCta33973 first fixed in |            |
      |          |12.2(33)SXI3                               |            |
      |----------+-------------------------------------------+------------|
      |12.2SY    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2SZ    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2T     |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2TPC   |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2XA    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2XB    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2XC    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2XD    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2XE    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2XF    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2XG    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2XH    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2XI    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2XJ    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2XK    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2XL    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2XM    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2XN    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2XNA   |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2XNB   |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2XNC   |12.2(33)XNC2                               |            |
      |----------+-------------------------------------------+------------|
      |12.2XND   |12.2(33)XND1; available 25th August 2009   |            |
      |----------+-------------------------------------------+------------|
      |12.2XO    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2XQ    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2XR    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2XS    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2XT    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2XU    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2XV    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2XW    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2YA    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2YB    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2YC    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2YD    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2YE    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2YF    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2YG    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2YH    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2YJ    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2YK    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2YL    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2YM    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2YN    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2YO    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2YP    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2YQ    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2YR    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2YS    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2YT    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2YU    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2YV    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2YW    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2YX    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2YY    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2YZ    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2ZA    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2ZB    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2ZC    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2ZD    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2ZE    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2ZF    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2ZG    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2ZH    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2ZJ    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2ZL    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2ZM    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2ZP    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2ZU    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2ZX    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2ZY    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.2ZYA   |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      | Affected |                                           |Recommended |
      |12.3-Based|            First Fixed Release            |  Release   |
      | Releases |                                           |            |
      |-------------------------------------------------------------------|
      |             There are no affected 12.3 based releases             |
      |-------------------------------------------------------------------|
      | Affected |                                           |Recommended |
      |12.4-Based|            First Fixed Release            |  Release   |
      | Releases |                                           |            |
      |----------+-------------------------------------------+------------|
      |12.4      |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.4JA    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.4JDA   |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.4JDC   |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.4JDD   |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.4JK    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.4JL    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.4JMA   |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.4JMB   |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.4JX    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.4MD    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.4MDA   |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.4MR    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.4SW    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |          |Releases up to 12.4(24)T are not           |            |
      |12.4T     |vulnerable; first fixed in 12.4(24)T2      |            |
      |          |available on 23-Oct-2009                   |            |
      |----------+-------------------------------------------+------------|
      |12.4XA    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.4XB    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.4XC    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.4XD    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.4XE    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.4XF    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.4XG    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.4XJ    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.4XK    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.4XL    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.4XM    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.4XN    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.4XP    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.4XQ    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.4XR    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.4XT    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.4XV    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.4XW    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.4XY    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.4XZ    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.4YA    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.4YB    |Not Vulnerable                             |            |
      |----------+-------------------------------------------+------------|
      |12.4YD    |Not Vulnerable                             |            |
      +-------------------------------------------------------------------+
      
      Cisco IOS XE Release Table
      +-------------------------
      
      +-------------------------------------------------------------------+
      |  Major   |              Availability of Repaired Releases         |
      | Release  |                                                        |
      |----------+--------------------------------------------------------|
      | Affected |                                                        |
      |   2.1    | There are no affected 2.1 based releases               |
      | Releases |                                                        |
      |----------+--------------------------------------------------------|
      | Affected |                                                        |
      |   2.2    | There are no affected 2.2 based releases               |
      | Releases |                                                        |
      |----------+--------------------------------------------------------|
      | Affected | Releases up to and including 2.3.1t are vulnerable;    |
      |   2.3    | First fixed in 2.3.2                                   |
      | Releases |                                                        |
      |----------+--------------------------------------------------------+
      | Affected | Releases up to and including 2.4.0 are vulnerable;     |
      |   2.4    | First fixed in 2.4.1, available 25th August 2009       |
      | Releases |                                                        |
      +----------+--------------------------------------------------------+
         
      Workarounds
      ===========
      
      For the first vulnerability, there are no workarounds on the affected
      device. Neighbors could be configured to discard routes that have
      more than one thousand AS numbers in the AS-path segments. This
      configuration will help prevent the further propagation of BGP
      updates with the AS path segments made up of greater than one
      thousand AS numbers.
      
      Note: Configuring "bgp maxas-limit [value]" on the affected device
      does not mitigate this vulnerability.
      
      For the second vulnerability, configuring "bgp maxas-limit [value]"
      on the affected device does mitigate this vulnerability. Cisco is
      recommends using a conservative value of 100 to mitigate this
      vulnerability.
      
      Consult the document "Protecting Border Gateway Protocol for the
      Enterprise" at the following link for additional best practices on
      protecting BGP infrastructures: 
      http://www.cisco.com/web/about/security/intelligence/protecting_bgp.html
      
      Obtaining Fixed Software
      ========================
      
      Cisco has released free software updates that address these
      vulnerabilities. Prior to deploying software, customers should
      consult their maintenance provider or check the software for feature
      set compatibility and known issues specific to their environment.
      
      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/en/US/docs/general/warranty/English/EU1KEN_.html
      or as otherwise set forth at Cisco.com Downloads at
      http://www.cisco.com/public/sw-center/sw-usingswc.shtml
      
      Do not contact psirt at cisco dot com or security-alert at cisco dot com for
      software upgrades.
      
      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 agreements with third-party support organizations,
      such as Cisco Partners, authorized resellers, or service providers
      should contact that support organization for guidance and assistance
      with the appropriate course of action in regards to this advisory.
      
      The effectiveness of any workaround or fix 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 or
      fix is the most appropriate for use in the intended network before it
      is deployed.
      
      Customers without Service Contracts
      +----------------------------------
      
      Customers who purchase direct from Cisco but do not hold a Cisco
      service contract, and customers who purchase through third-party
      vendors but are unsuccessful in obtaining fixed software through
      their point of sale should acquire 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
      
      Customers should have their product serial number available and be
      prepared to give the URL of this notice as evidence of entitlement to
      a free upgrade. Free upgrades for non-contract customers must be
      requested through the TAC.
      
      Refer to 
      http://www.cisco.com/en/US/support/tsd_cisco_worldwide_contacts.html
      for additional TAC contact information, including localized 
      telephone numbers, and instructions and e-mail addresses for use
      in various languages.
      
      Exploitation and Public Announcements
      =====================================
      
      The Cisco PSIRT is not aware of malicious exploitation of either of
      these vulnerabilities, although we are aware of some customers who
      have seen the first vulnerability triggered within their
      infrastructures. Further investigation of those incidents seems to
      indicate that the vulnerability has been accidentally triggered.
      
      These vulnerabilities were discovered via internal product testing.
      
      Status of this Notice: FINAL
      ============================
      
      This information is Cisco Highly Confidential - Do not redistribute.
      
      THIS IS A DRAFT VERSION OF A SECURITY NOTICE THAT CONTAINS UNRELEASED
      INFORMATION ABOUT CISCO PRODUCTS. DISTRIBUTION WITHIN CISCO IS
      LIMITED TO PERSONNEL WITH A NEED TO KNOW. THIS DRAFT MAY CONTAIN
      ERRORS OR OMIT IMPORTANT INFORMATION.
      
      THIS DOCUMENT IS PROVIDED ON AN "AS IS" BASIS AND DOES NOT IMPLY ANY
      KIND OF GUARANTEE OR WARRANTY, INCLUDING THE WARRANTIES OF
      MERCHANTABILITY OR FITNESS FOR A PARTICULAR USE. YOUR USE OF THE
      INFORMATION ON THE DOCUMENT OR MATERIALS LINKED FROM THE DOCUMENT IS
      AT YOUR OWN RISK. CISCO RESERVES THE RIGHT TO CHANGE OR UPDATE THIS
      DOCUMENT AT ANY TIME.
      
      Distribution
      ============
      
      This advisory is posted on Cisco's worldwide website at:
         
      http://www.cisco.com/warp/public/707/cisco-sa-20090729-bgp.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-bulletins at lists dot first dot org
        * 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.grok dot org dot uk
        * comp.dcom.sys.cisco at newsgate dot cisco dot com
      
      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 1.0   | 2009-July-29 1600    | Initial public release    |
      +-------------------------------------------------------------------+
      
      Cisco Security Procedures
      =========================
      
      Complete information on reporting security vulnerabilities in Cisco
      products, obtaining assistance with security incidents, and
      registering to receive security information from Cisco, is available
      on Cisco's worldwide website at 
      http://www.cisco.com/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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