[apops] Cisco Security Advisory: Cisco IOS Software Layer 2 Tunneling Pr

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  • Subject: [apops] Cisco Security Advisory: Cisco IOS Software Layer 2 Tunneling Protocol (L2TP) Denial of Service Vulnerability
  • From: Cisco Systems Product Security Incident Response Team <psirt at cisco dot com>
  • Date: Wed, 24 Sep 2008 17:50:00 +0200
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      Cisco Security Advisory: Cisco IOS Software Layer 2 Tunneling
      Protocol (L2TP) Denial of Service Vulnerability
      
      Advisory ID: cisco-sa-20080924-l2tp
      
      http://www.cisco.com/warp/public/707/cisco-sa-20080924-l2tp.shtml
      
      Revision 1.0
      
      For Public Release 2008 September 24 1600 UTC (GMT)
      
      - ---------------------------------------------------------------------
      
      Summary
      =======
      
      A vulnerability exists in the Cisco IOS software implementation of
      Layer 2 Tunneling Protocol (L2TP), which affects limited Cisco IOS
      software releases.
      
      Several features enable the L2TP mgmt daemon process within Cisco IOS
      software, including but not limited to Layer 2 virtual private
      networks (L2VPN), Layer 2 Tunnel Protocol Version 3 (L2TPv3), Stack
      Group Bidding Protocol (SGBP) and Cisco Virtual Private Dial-Up
      Networks (VPDN). Once this process is enabled the device is
      vulnerable.
      
      This vulnerability will result in a reload of the device when
      processing a specially crafted L2TP packet.
      
      Cisco has released free software updates that address this
      vulnerability.
      
      Workarounds that mitigate this vulnerability are available.
      
      This advisory is posted at 
      http://www.cisco.com/warp/public/707/cisco-sa-20080924-l2tp.shtml
      
      Note:  The September 24, 2008 IOS Advisory bundled publication
      includes twelve Security Advisories. Eleven of the advisories address
      vulnerabilities in Cisco's IOS software, and one advisory addresses
      vulnerabilities in Cisco Unified Communications Manager. Each
      Advisory lists the releases that correct the vulnerability described
      in the Advisory. Please reference the following software table to
      find a release that fixes all published IOS software Advisories as of
      September 24th, 2008:
      
      http://www.cisco.com/warp/public/707/cisco-sa-20080924-bundle.shtml
      
      Individual publication links are listed below:
      
        * http://www.cisco.com/warp/public/707/cisco-sa-20080924-iosips.shtml
        * http://www.cisco.com/warp/public/707/cisco-sa-20080924-ssl.shtml
        * http://www.cisco.com/warp/public/707/cisco-sa-20080924-sip.shtml
        * http://www.cisco.com/warp/public/707/cisco-sa-20080924-cucm.shtml
        * http://www.cisco.com/warp/public/707/cisco-sa-20080924-vpn.shtml
        * http://www.cisco.com/warp/public/707/cisco-sa-20080924-mfi.shtml
        * http://www.cisco.com/warp/public/707/cisco-sa-20080924-ipc.shtml
        * http://www.cisco.com/warp/public/707/cisco-sa-20080924-ubr.shtml
        * http://www.cisco.com/warp/public/707/cisco-sa-20080924-multicast.shtml
        * http://www.cisco.com/warp/public/707/cisco-sa-20080924-sccp.shtml
        * http://www.cisco.com/warp/public/707/cisco-sa-20080924-iosfw.shtml
      
      Affected Products
      =================
      
      All devices running affected versions of 12.2 or 12.4 Cisco IOS
      system software and that have a vulnerable configuration are affected
      by this vulnerability.
      
      Vulnerable Products
      +------------------
      
      To determine if a device is vulnerable, first confirm that the device
      is running an affected version of 12.2 or 12.4 Cisco IOS system
      software. Then check for the process L2TP mgmt daemon running on the
      device.
      
      To determine the software version running on a Cisco product, log in
      to the device and issue the show version command to display the
      system banner. Cisco IOS software will identify itself as
      "Internetwork Operating System Software" or simply "IOS." On the next
      line of output, the image name will be displayed between parentheses,
      followed by "Version" and the IOS release name. Other Cisco devices
      will not have the show version command or will give different output.
      
      The following example identifies a Cisco product that is running
      Cisco IOS Software Release 12.4(11)T2:
      
          Router#show version
          Cisco IOS Software, 7200 Software (C7200-ADVSECURITYK9-M), Version 12.4(11)T2, RELEASE SOFTWARE (fc4)
          Technical Support: http://www.cisco.com/techsupport
          Copyright (c) 1986-2007 by Cisco Systems, Inc.
          Compiled Tue 01-May-07 04:19 by prod_rel_team
      
      
          <output truncated>
      
      
      Additional information on the Cisco IOS release naming conventions
      can be found in the document entitled "White Paper: Cisco IOS
      Reference Guide," which is available at 
      http://www.cisco.com/warp/public/620/1.html
      
      To check if the process L2TP mgmt daemon is running on a device, log
      into the command line interface (CLI) and issue the command show
      processes | include L2TP . (NOTE: The command is case sensitive.) If
      the output returns a line with the process name L2TP mgmt daemon, the
      device is vulnerable. The following example shows a device running
      the L2TP mgmt daemon process:
      
          Router#show processes | include L2TP
           158 Mwe 62590FE4            4          3    133322900/24000  0 L2TP mgmt daemon
          Router#
      
      The L2TP mgmt daemon is started by several different types of
      configurations that may be deployed in networks that leverage the
      L2TP protocol. If any of the following commands appear within a
      device's configuration, show running-config, then the device will
      have started the L2TP mgmt daemon and is vulnerable.
      
        * Device is configured with Virtual Private Dial-Up Networks
          (VPDN).
          The command vpdn enable will appear in the device configuration.
        * Device is configured for L2TP or L2TPv3 Client-Initiated VPDN
          Tunneling.
          The command pseudowire peer-ip-address vcid pw-class 
          pw-class-name " appears in the device configuration.
        * Device is configured with Stack Group Bidding Protocol (SGBP).
          The command sgbp group group-name will appear in the device
          configuration.
        * A L2TP signaling template has been defined.
          The command l2tp-class l2tp-class name will appear in the device
          configuration.
        * Devices configured for Layer 2 Tunnel Protocol Version 3
          The commands pseudowire-class pseudowire-class name and a
          successfully applied interface xconnect command will appear in
          the device configuration.
      
      Products Confirmed Not Vulnerable
      +--------------------------------
      
        * Devices that are running Cisco IOS versions that are not
          explicitly listed in the software table below as vulnerable, are
          not affected.
        * Cisco IOS XR is not affected.
        * Cisco IOS XE is not affected.
      
      No other Cisco products are currently known to be affected by this
      vulnerability.
      
      Details
      =======
      
      Documented in RFC2661, L2TP and RFC3931, L2TPv3 are protocols for
      tunneling network traffic between two peers over an existing network.
      
      A device running affected 12.2 and 12.4 versions of Cisco IOS and
      that has the L2TP mgmt daemon process running will reload when
      processing a specially crafted L2TP packet.
      
      Several features leverage the L2TP protocol and start the L2TP mgmt
      daemon within Cisco IOS. These features have been outlined in this
      advisory under the Vulnerable Products section.
      
      This vulnerability is documented in Cisco bug ID CSCsh48879 
      and Common Vulnerabilities and Exposures (CVE) identifier 
      CVE-2008-3813 has been assigned to this vulnerability.
      
      Vulnerability Scoring Details
      =============================
      
      Cisco has provided scores for the vulnerability 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
      
      CSCsh48879 - Crafted L2TP packet triggers a device reload.
      
      CVSS Base Score - 7.8
      
              Access Vector          - Network
              Access Complexity      - Low
              Authentication         - None
              Confidentiality Impact - None
              Integrity Impact       - None
              Availability Impact    - Complete
      
      CVSS Temporal Score - 6.4
      
              Exploitability          - Functional
              Remediation Level       - Official-Fix
              Report Confidence       - Confirmed
      
      Impact
      ======
      
      Successful exploitation of the vulnerability will result in a reload
      of the device. Repeated exploitation may result in an extended denial
      of service (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   |                                   |                |
      |-------------------------------------------------------------------|
      | There are no affected 12.0 based releases                         |
      |-------------------------------------------------------------------|
      |   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                    |                |
      |--------------+-----------------------------------+----------------|
      | 12.2IRB      | 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                    |                |
      |--------------+-----------------------------------+----------------|
      | 12.2JA       | 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                    |                |
      |--------------+-----------------------------------+----------------|
      |              | Note: Releases prior to 12.2(37)  |                |
      | 12.2SE       | SE are not vulnerable. First      | 12.2(46)SE     |
      |              | fixed in 12.2(44)SE               |                |
      |--------------+-----------------------------------+----------------|
      | 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                    |                |
      |--------------+-----------------------------------+----------------|
      |              | Note: Releases prior to 12.2(37)  |                |
      | 12.2SG       | SG are not vulnerable. First      | 12.2(46)SG1    |
      |              | Fixed in 12.2(44)SG               |                |
      |--------------+-----------------------------------+----------------|
      | 12.2SGA      | Not Vulnerable                    |                |
      |--------------+-----------------------------------+----------------|
      | 12.2SL       | Not Vulnerable                    |                |
      |--------------+-----------------------------------+----------------|
      | 12.2SM       | Not Vulnerable                    |                |
      |--------------+-----------------------------------+----------------|
      | 12.2SO       | Not Vulnerable                    |                |
      |--------------+-----------------------------------+----------------|
      | 12.2SRA      | Not Vulnerable                    |                |
      |--------------+-----------------------------------+----------------|
      | 12.2SRB      | 12.2(33)SRB1                      | 12.2(33)SRB4   |
      |--------------+-----------------------------------+----------------|
      | 12.2SRC      | Not Vulnerable                    |                |
      |--------------+-----------------------------------+----------------|
      | 12.2SU       | Not Vulnerable                    |                |
      |--------------+-----------------------------------+----------------|
      | 12.2SV       | Not Vulnerable                    |                |
      |--------------+-----------------------------------+----------------|
      | 12.2SVA      | Not Vulnerable                    |                |
      |--------------+-----------------------------------+----------------|
      | 12.2SVC      | Not Vulnerable                    |                |
      |--------------+-----------------------------------+----------------|
      | 12.2SVD      | 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                    |                |
      |--------------+-----------------------------------+----------------|
      | 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                    |                |
      |--------------+-----------------------------------+----------------|
      | 12.2XO       | 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                    |                |
      |--------------+-----------------------------------+----------------|
      | 12.2ZP       | 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                    |                |
      |--------------+-----------------------------------+----------------|
      | 12.4JK       | Not Vulnerable                    |                |
      |--------------+-----------------------------------+----------------|
      | 12.4JL       | Not Vulnerable                    |                |
      |--------------+-----------------------------------+----------------|
      | 12.4JMA      | Not Vulnerable                    |                |
      |--------------+-----------------------------------+----------------|
      | 12.4JMB      | Not Vulnerable                    |                |
      |--------------+-----------------------------------+----------------|
      | 12.4JMC      | Not Vulnerable                    |                |
      |--------------+-----------------------------------+----------------|
      | 12.4JX       | Not Vulnerable                    |                |
      |--------------+-----------------------------------+----------------|
      | 12.4MD       | Not Vulnerable                    |                |
      |--------------+-----------------------------------+----------------|
      |              | Note: Releases prior to 12.4(11)  |                |
      | 12.4MR       | MR are not vulnerable. First      | 12.4(19)MR     |
      |              | fixed in 12.4(16)MR               |                |
      |--------------+-----------------------------------+----------------|
      |              |                                   | 12.4(15)SW2;   |
      | 12.4SW       | 12.4(11)SW3                       | Available on   |
      |              |                                   | 28-SEP-08      |
      |--------------+-----------------------------------+----------------|
      |              | Note: Releases prior to 12.4(11)T |                |
      | 12.4T        | are not vulnerable. First fixed   | 12.4(15)T7     |
      |              | in 12.4(15)T                      |                |
      |--------------+-----------------------------------+----------------|
      | 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       | Vulnerable; first fixed in 12.4T  | 12.4(15)T7     |
      |--------------+-----------------------------------+----------------|
      | 12.4XK       | Not Vulnerable                    |                |
      |--------------+-----------------------------------+----------------|
      | 12.4XL       | Not Vulnerable                    |                |
      |--------------+-----------------------------------+----------------|
      | 12.4XM       | Not Vulnerable                    |                |
      |--------------+-----------------------------------+----------------|
      | 12.4XN       | Not Vulnerable                    |                |
      |--------------+-----------------------------------+----------------|
      | 12.4XP       | Not Vulnerable                    |                |
      |--------------+-----------------------------------+----------------|
      | 12.4XQ       | Not Vulnerable                    |                |
      |--------------+-----------------------------------+----------------|
      | 12.4XT       | Not Vulnerable                    |                |
      |--------------+-----------------------------------+----------------|
      | 12.4XV       | Vulnerable; contact TAC           |                |
      |--------------+-----------------------------------+----------------|
      | 12.4XW       | 12.4(11)XW1                       | 12.4(11)XW9    |
      |--------------+-----------------------------------+----------------|
      | 12.4XY       | Not Vulnerable                    |                |
      |--------------+-----------------------------------+----------------|
      | 12.4XZ       | Not Vulnerable                    |                |
      |--------------+-----------------------------------+----------------|
      | 12.4YA       | Not Vulnerable                    |                |
      +-------------------------------------------------------------------+
      
      Workarounds
      ===========
      
      The following workarounds have been identified for this
      vulnerability.
      
      Note:  L2TP implementations will need to allow UDP 1701, from trusted
      addresses to infrastructure addresses. This does not provide for a
      full mitigation as the source addresses may be spoofed.
      
      Note:  L2TPv3 over IP only implementations need to deny all UDP 1701
      from anywhere to the infrastructure addresses.
      
        * Infrastructure Access Control Lists
          Although it is often difficult to block traffic that transits a
          network, it is possible to identify traffic that should never be
          allowed to target infrastructure devices and block that traffic
          at the border of networks. Infrastructure Access Control Lists
          (iACLs) are a network security best practice and should be
          considered as a long-term addition to good network security as
          well as a workaround for these specific vulnerabilities. The iACL
          example below should be included as part of the deployed
          infrastructure access-list which will protect all devices with IP
          addresses in the infrastructure IP address range:
      
      
      
              !--- Permit L2TP UDP 1701 packets from all trusted
              !--- sources destined to infrastructure addresses.
              !--- NOTE: This does not prevent spoofed attacks.
              !---           To be a full mitigation, no trusted source
              !---           addresses should be listed.
              !---           Omit this line if using a L2TPv3 over IP implementation only.
      
      
              access-list 150 permit udp TRUSTED_SOURCE_ADDRESSES MASK
                 INFRASTRUCTURE_ADDRESSES MASK eq 1701
      
      
              !--- Deny L2TP UDP 1701 packets from all
              !--- sources destined to infrastructure addresses.
      
      
              access-list 150 deny udp any INFRASTRUCTURE_ADDRESSES MASK eq 1701
      
      
              !--- If using a L2TPv3 over IP implementation ensure to allow L2TPv3
      
      
              access-list 150 permit 115 <source_ip_address and mask>
                 <destination_ip_address and mask>
      
      
              !--- Permit/deny all other Layer 3 and Layer 4 traffic in accordance
              !--- with existing security policies and configurations
              !--- Permit all other traffic to transit the device.
      
      
              access-list 150 permit ip any any
      
      
              !--- Apply access-list to all interfaces (only one example shown)
      
      
              interface serial 2/0
              ip access-group 150 in
      
          The white paper entitled "Protecting Your Core: Infrastructure
          Protection Access Control Lists" presents guidelines and
          recommended deployment techniques for infrastructure protection
          access lists. This white paper can be obtained at the following
          link: 
          http://www.cisco.com/en/US/tech/tk648/tk361/technologies_white_paper09186a00801a1a55.shtml
      
        * Control Plane Policing
          Control Plane Policing (CoPP) can be used to block L2TP access to
          the device. Cisco IOS software releases 12.0S, 12.2SX, 12.2S,
          12.3T, 12.4, and 12.4T support the CoPP feature. CoPP can be
          configured on a device to protect the management and control
          planes and minimize the risk and effectiveness of direct
          infrastructure attacks by explicitly permitting only authorized
          traffic that is sent to infrastructure devices in accordance with
          existing security policies and configurations. The CoPP example
          below should be included as part of the deployed CoPP which will
          protect all devices with IP addresses in the infrastructure IP
          address range.
      
      
      
              !--- Deny all trusted source L2TP UDP traffic sent to all IP addresses
              !--- configured on all interfaces of the affected device so that it
              !--- will not be policed by the CoPP feature.
      
              !--- NOTE: This does not prevent spoofed attacks.
              !---           To be a full mitigation, no trusted source
              !---           addresses should be listed.
              !---           Omit this line if using an L2TPv3 over IP implementation only.
      
      
              access-list 111 deny udp TRUSTED_SOURCE_ADDRESSES MASK
                 INFRASTRUCTURE_ADDRESSES MASK eq 1701
      
      
              !--- Permit all L2TP UDP traffic sent to all IP addresses
              !--- configured on all interfaces of the affected device so that it
              !--- will be policed and dropped by the CoPP feature
      
      
              access-list 111 permit udp any INFRASTRUCTURE_ADDRESSES MASK eq 1701
      
      
              !--- If using an L2TPv3 over IP implementation ensure not to drop L2TPv3
      
      
              access-list 111 deny 115 <source_ip_address and mask>
                 <destination_ip_address and mask>
      
      
              !--- Permit (Police or Drop)/Deny (Allow) all other Layer3 and Layer4
              !--- traffic in accordance with existing security policies and
              !--- configurations for traffic that is authorized to be sent
              !--- to infrastructure devices
      
              !--- Create a Class-Map for traffic to be policed by
              !--- the CoPP feature
      
      
      
              class-map match-all drop-l2tp-class
              match access-group 111
      
      
      
              !--- Create a Policy-Map that will be applied to the
              !--- Control-Plane of the device.
      
      
              policy-map drop-l2tp-traffic
              class drop-l2tp-class
              drop
      
      
      
              !--- Apply the Policy-Map to the 
              !--- Control-Plane of the device
      
      
              control-plane
      
              service-policy input drop-l2tp-traffic
      
          In the above CoPP example, the access control list entries (ACEs)
          that match the potential exploit packets with the "permit" action
          result in these packets being discarded by the policy-map "drop"
          function, while packets that match the "deny" action (not shown)
          are not affected by the policy-map drop function. Please note
          that the policy-map syntax is different in the 12.2S and 12.0S
          Cisco IOS trains:
      
              policy-map drop-l2tp-traffic
              class drop-l2tp-class
              police 32000 1500 1500 conform-action drop exceed-action drop
      
          Additional information on the configuration and use of the CoPP
          feature is available at the following link: 
          http://www.cisco.com/web/about/security/intelligence/coppwp_gs.html
      
      Additional mitigations that can be deployed on Cisco devices within
      the network are available in the Cisco Applied Mitigation Bulletin
      companion document for this advisory: 
      http://www.cisco.com/warp/public/707/cisco-amb-20080924-l2tp.shtml
      
      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/products/prod_warranties_item09186a008088e31f.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/warp/public/687/Directory/DirTAC.shtml
      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 any public announcements or malicious
      use of the vulnerability described in this advisory.
      
      This vulnerability was found by Cisco through internal testing.
      
      Status of this Notice: FINAL
      ============================
      
      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.
      
      A stand-alone copy or Paraphrase of the text of this document 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 is posted on Cisco's worldwide website at :
      
      http://www.cisco.com/warp/public/707/cisco-sa-20080924-l2tp.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
        * 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 |                   | Initial |
      | 1.0      | 2008-September-24 | 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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