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Cisco Security Advisory: Cisco VPN 3000 Concentrator Vulnerabilities
From: Cisco Systems Product Security Incident Response Team <psirt () cisco com>
Date: Wed, 7 May 2003 09:00:00 -0700 (UTC)

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      Cisco Security Advisory: Cisco VPN 3000 Concentrator Vulnerabilities

Revision 1.0

  For Public Release 2003 May 7 at 1600 UTC (GMT)

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

Contents

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

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

Summary

   This advisory documents vulnerabilities for the Cisco VPN 3000 series
   concentrators and Cisco VPN 3002 Hardware Client. These vulnerabilities
   are documented as Cisco bug ID CSCea77143 (IPSec over TCP), CSCdz15393
   (SSH), and CSCdt84906 (ICMP). There are workarounds available to mitigate
   the effects of these vulnerabilities. Upgrading to the latest version of
   code for the Cisco VPN 3000 series concentrators and Cisco VPN 3002
   Hardware Client, version 4.0.1 and 3.6.7F, would protect against all of
   these documented vulnerabilities.

   This advisory will be posted at
   http://www.cisco.com/warp/public/707/cisco-sa-20030507-vpn3k.shtml.

Affected Products

   The Cisco VPN 3000 series concentrators are affected by these
   vulnerabilities. This series includes models 3005, 3015, 3030, 3060, 3080
   and the Cisco VPN 3002 Hardware Client.

   +------------------------------------------+
   |  DDTS - Description  | Affected Releases |
   |----------------------+-------------------|
   |                      |  * 4.0.REL        |
   |                      |                   |
   |                      |  * 3.6.REL through|
   |CSCea77143 - enabling |    3.6.7F         |
   |IPSec over TCP        |                   |
   |vulnerability         |  * 3.5.x          |
   |                      |                   |
   |                      |  * 3.1.x, 3.0.x   |
   |                      |    and 2.x.x are  |
   |                      |    NOT affected.  |
   |----------------------+-------------------|
   |                      |  * 3.6.REL through|
   |                      |    3.6.7          |
   |                      |                   |
   |CSCdz15393 - malformed|  * 3.5.x          |
   |SSH initialization    |                   |
   |packet vulnerability  |  * 3.1.x          |
   |                      |                   |
   |                      |  * 3.0.x          |
   |                      |                   |
   |                      |  * 2.x.x          |
   |----------------------+-------------------|
   |                      |  * 3.6.REL through|
   |                      |    3.6.7A         |
   |                      |                   |
   |CSCdt84906 - malformed|  * 3.5.x          |
   |ICMP traffic          |                   |
   |vulnerability         |  * 3.1.x          |
   |                      |                   |
   |                      |  * 3.0.x          |
   |                      |                   |
   |                      |  * 2.x.x          |
   +------------------------------------------+

   These vulnerabilities do not affect the VPN Client software nor the Cisco
   VPN 5000 series concentrators. No other Cisco products are currently known
   to be affected by these vulnerabilities.

   To determine if a Cisco VPN 3000 series concentrator is running affected
   software, check the software revision via the web interface or the console
   menu.

Details

   +------------------------------------------+
   |    DDTS -    |          Details          |
   | Description  |                           |
   |--------------+---------------------------|
   |              |Enabling IPSec over TCP for|
   |              |a port on the VPN 3000     |
   |              |series concentrator allows |
   |              |TCP traffic on that port to|
   |              |traverse through the       |
   |              |concentrator and reach the |
   |              |private network.           |
   |              |                           |
   |              |For example, if one        |
   |              |configures IPSec over TCP  |
   |              |to use port 80 and the     |
   |              |private network is routable|
   |              |to from the public network |
   |              |i.e. a workstation on the  |
   |              |public network has the VPN |
   |              |3000 series concentrator   |
   |CSCea77143 -  |configured as the gateway  |
   |enabling IPSec|for the private network IP |
   |over TCP      |address space, one can     |
   |vulnerability |browse the web servers on  |
   |              |the private network        |
   |              |configured to serve port 80|
   |              |from the workstation on the|
   |              |public network without any |
   |              |form of authentication.    |
   |              |Another example, if IPSec  |
   |              |over TCP was not configured|
   |              |for port 80 but was        |
   |              |configured for its default |
   |              |port of 10000 and if there |
   |              |was a server listening for |
   |              |telnet connections on port |
   |              |10000 on the private       |
   |              |network, then one could    |
   |              |telnet to that server from |
   |              |the workstation on the     |
   |              |public network.            |
   |--------------+---------------------------|
   |CSCdz15393 -  |A malformed SSH            |
   |malformed SSH |initialization packet sent |
   |initialization|during the initial SSH     |
   |packet        |session setup may reload   |
   |vulnerability |the VPN 3000 series        |
   |              |concentrator.              |
   |--------------+---------------------------|
   |              |A flood of malformed ICMP  |
   |CSCdt84906 -  |packets could result in    |
   |malformed ICMP|performance degradation on |
   |traffic       |the VPN 3000 series        |
   |vulnerability |concentrator and may even  |
   |              |cause the concentrator to  |
   |              |reload.                    |
   +------------------------------------------+

   These vulnerabilities are documented in the Cisco Bug Toolkit
   as Bug IDs CSCea77143, CSCdz15393, and CSCdt84906, and can
   be viewed after 2003 May 8 at 1600 UTC. To access this tool, you must be a
   registered user and you must be logged in.

   For more information on IPSec over TCP please refer to the documentation
   available at
   http://www.cisco.com/univercd/cc/td/doc/product/vpn/vpn3000/4_0/config/tunnel.htm#1279809

   The Inter networking Terms and Cisco Systems Acronyms online guides can be
   found at http://www.cisco.com/univercd/cc/td/doc/cisintwk/.

Impact

   +------------------------------------------+
   |DDTS - Description |        Impact        |
   |-------------------+----------------------|
   |                   |Unintended access to  |
   |                   |the private network on|
   |                   |the VPN 3000 series   |
   |CSCea77143 -       |concentrator. This    |
   |enabling IPSec over|vulnerability enables |
   |TCP vulnerability  |one to access internal|
   |                   |hosts on the IPSec    |
   |                   |over TCP configured   |
   |                   |ports.                |
   |-------------------+----------------------|
   |CSCdz15393 -       |This vulnerability can|
   |malformed SSH      |be exploited to       |
   |initialization     |initiate a Denial of  |
   |packet             |Service on the VPN    |
   |vulnerability      |3000 series           |
   |                   |concentrator.         |
   |-------------------+----------------------|
   |                   |This vulnerability may|
   |CSCdt84906 -       |cause a performance   |
   |malformed ICMP     |degradation on the VPN|
   |traffic            |3000 series           |
   |vulnerability      |concentrator and may  |
   |                   |even result in a      |
   |                   |Denial of Service.    |
   +------------------------------------------+

Software Versions and Fixes

   +------------------------------------------+
   |   DDTS - Description   | Fixed Releases  |
   |------------------------+-----------------|
   |                        |  * 4.0.1 and    |
   |                        |    later        |
   |                        |                 |
   |CSCea77143 - enabling   |  * 3.6.7F and   |
   |IPSec over TCP          |    later        |
   |vulnerability           |                 |
   |                        |  * 3.1.x, 3.0.x |
   |                        |    and 2.x.x are|
   |                        |    NOT affected |
   |------------------------+-----------------|
   |                        |  * 4.0.REL and  |
   |CSCdz15393 - malformed  |    later        |
   |SSH initialization      |                 |
   |packet vulnerability    |  * 3.6.7 and    |
   |                        |    later        |
   |------------------------+-----------------|
   |                        |  * 4.0.REL and  |
   |CSCdt84906 - malformed  |    later        |
   |ICMP traffic            |                 |
   |vulnerability           |  * 3.6.7A and   |
   |                        |    later        |
   +------------------------------------------+

   The procedure to upgrade to the fixed software version is detailed at
   http://www.cisco.com/univercd/cc/td/doc/product/vpn/vpn3000/.

Obtaining Fixed Software

   Cisco is offering free software upgrades to address these vulnerabilities
   for all affected customers. Customers may only install and expect support
   for the feature sets they have purchased. By installing, downloading,
   accessing or otherwise using such software upgrades, Customers agree to be
   bound by the terms of Cisco's software license terms found at
   http://www.cisco.com/public/sw-license-agreement.html, or as otherwise set
   forth at the Cisco Connection Online Software Center at
   http://www.cisco.com/public/sw-center/sw-usingswc.shtm.

   Customers with service contracts should contact their regular update
   channels to obtain the free software upgrade identified via this advisory.
   For most customers with service contracts, this means that upgrades should
   be obtained through the Software Center on Cisco's worldwide website at
   http://www.cisco.com/public/sw-center/vpn/3000/ . To access the software
   download URL, you must be a registered user and you must be logged in.

   Customers whose Cisco products are provided or maintained through prior or
   existing agreement with third-party support organizations such as Cisco
   Partners, authorized resellers, or service providers should contact that
   support organization for assistance with the upgrade, which should be free
   of charge.

   Customers who purchase direct from Cisco but who do not hold a Cisco
   service contract and customers who purchase through third-party vendors
   but are unsuccessful at obtaining fixed software through their point of
   sale should get their upgrades by contacting the Cisco Technical
   Assistance Center (TAC). TAC contacts are as follows.

     * +1 800 553 2447 (toll free from within North America)

     * +1 408 526 7209 (toll call from anywhere in the world)

     * e-mail: tac () cisco com

   Please have your product serial number available and give the URL of this
   notice as evidence of your entitlement to a free upgrade. Free upgrades
   for non-contract customers must be requested through the TAC.

   Please do not contact either "psirt () cisco com" or
   "security-alert () cisco com" for software upgrades.

Workarounds

   The Cisco PSIRT recommends that affected users upgrade to a fixed software
   version of code.

   +------------------------------------------+
   |DDTS - Description|      Workaround       |
   |------------------+-----------------------|
   |                  |Add rules, to the      |
   |                  |filter for the private |
   |                  |interface, that        |
   |                  |restrict outgoing      |
   |                  |traffic on ports       |
   |                  |configured for use by  |
   |CSCea77143 -      |IPSec over TCP on the  |
   |enabling IPSec    |VPN concentrator. This |
   |over TCP          |would not stop the     |
   |vulnerability     |traffic from the public|
   |                  |network reaching the   |
   |                  |VPN 3000 concentrator  |
   |                  |itself but would       |
   |                  |prevent the traffic    |
   |                  |from reaching the      |
   |                  |servers on the private |
   |                  |network.               |
   |------------------+-----------------------|
   |                  |Restrict access to the |
   |                  |SSH server on the VPN  |
   |CSCdz15393 -      |3000 series            |
   |malformed SSH     |concentrator by        |
   |initialization    |applying appropriate   |
   |packet            |rules to the filters   |
   |vulnerability     |for the interfaces such|
   |                  |that connections are   |
   |                  |permitted only from    |
   |                  |trusted client hosts.  |
   |------------------+-----------------------|
   |CSCdt84906 -      |Only allow legitimate  |
   |malformed ICMP    |ICMP traffic to reach  |
   |traffic           |the VPN 3000 series    |
   |vulnerability     |concentrator's         |
   |                  |interface.             |
   +------------------------------------------+

Exploitation and Public Announcements

   The Cisco PSIRT is not aware of any public announcements or malicious use
   of the vulnerabilities described in this advisory.

   These vulnerabilities were reported to PSIRT by internal development
   testing.

   The Cisco PSIRT is not aware of any public announcements or malicious use
   of the vulnerability described in this advisory.

Status of This Notice: FINAL

   This is a final advisory. Although Cisco cannot guarantee the accuracy of
   all statements in this advisory, all of the facts have been checked to the
   best of our ability. Cisco does not anticipate issuing updated versions of
   this advisory unless there is some material change in the facts. Should
   there be a significant change in the facts, Cisco will update this
   advisory.

   A stand-alone copy or paraphrase of the text of this security advisory
   that omits the distribution URL in the following section is an
   uncontrolled copy, and may lack important information or contain factual
   errors.

Distribution

   This advisory will be posted on Cisco's worldwide website at
   http://www.cisco.com/warp/public/707/cisco-sa-20030507-vpn3k.shtml.

   In addition to worldwide web posting, a text version of this notice is
   clear-signed with the Cisco PSIRT PGP key and is posted to the following
   e-mail and Usenet news recipients.

     * cust-security-announce () cisco com

     * bugtraq () securityfocus com

     * first-teams () first org (includes CERT/CC)

     * cisco () spot colorado edu

     * comp.dcom.sys.cisco

     * firewalls () lists gnac com

     * Various internal Cisco mailing lists

   Future updates of this advisory, if any, will be placed on Cisco's
   worldwide website, but may or may not be actively announced on mailing
   lists or newsgroups. Users concerned about this problem are encouraged to
   check the above URL for any updates.

Revision History

   +------------------------------------------+
   |Revision 1.0|2003-May-7|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/warp/public/707/sec_incident_response.shtml. This
   includes instructions for press inquiries regarding Cisco security
   notices. All Cisco security advisories are available at
   http://www.cisco.com/go/psirt.

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

   This notice is Copyright 2003 by Cisco Systems, Inc. This notice may be
   redistributed freely after the release date given at the top of the text,
   provided that redistributed copies are complete and unmodified, and
   include all date and version information.

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