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securityvulnsSecurityvulnsSECURITYVULNS:DOC:1769
HistoryJun 28, 2001 - 12:00 a.m.

Security Advisory: Multiple SSH vulnerabilities

2001-06-2800:00:00
vulners.com
39
JSON

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

            Security Advisory: Multiple SSH vulnerabilities

Revision 1.0 - INTERIM

For public release 2001 June 27 08:00 (UTC -0800)
_________________________________________________________________

Summary

Three different Cisco product lines are susceptible to multiple
vulnerabilities in the Secure Shell (SSH) protocol. These issues are
inherent to the SSH protocol version 1.5, which is implemented in
several Cisco product lines.

By exploiting the weakness in the SSH protocol, it is possible to
insert an arbitrary commands into an established SSH session, collect
information that may help in brute force key recovery, or brute force
a session key.

Affected product lines are:

 All devices running Cisco IOS software supporting SSH. That includes
      routers and switches running Cisco IOS.
      
 Catalyst 6000 switches running CatOS.
      
 Cisco PIX Firewall.
      
      No other Cisco products are vulnerable.
      
      It is possible to mitigate this vulnerability by preventing, or
      having a control over, interception of SSH traffic.
      
      This advisory will be available at
      http://www.cisco.com/warp/public/707/SSH-multiple-pub.html

Affected Products

      The following table depicts the affected products categories.

±--------------±----------------±------------------±---------------+
| | CRC-32 check | Traffic analysis | Key recovery |
±--------------±----------------±------------------±---------------+
|IOS | Vulnerable | Vulnerable | Vulnerable |
| | CSCdt96253 | CSCdt57231 | CSCdu37371 |
±--------------±----------------±------------------±---------------+
|PIX | Vulnerable | Not vulnerable | Not vulnerable |
| | CSCdt73353 | | |
±--------------±----------------±------------------±---------------+
|VPN3000 | Not vulnerable | Not vulnerable | Not vulnerable |
±--------------±----------------±------------------±---------------+
|Catalyst 6000 | Vulnerable | Vulnerable | Not vulnerable |
| | CSCdt72996 | CSCdt55357 | |
±--------------±----------------±------------------±---------------+

      Per product category, the following software releases are
      vulnerable:

±-------±--------------------------------------------------------------+
|IOS | All 12.0, and upwards, releases that conatins support for SSH.|
±-------±--------------------------------------------------------------+
|PIX | 5.2(5) and 5.3.(1) |
±-------±--------------------------------------------------------------+
|CatOS | 6.2(0.110) |
±-------±--------------------------------------------------------------+
|VPN3000 | Not vulnerable |
±-------±--------------------------------------------------------------+

Details

      An implementation of SSH in multiple Cisco products are
      vulnerable to three different vulnerabilities. These
      vulnerabilities are:
      
    CRC-32 integrity check vulnerability
            This vulnerability has been described in a CORE SDI S.A.
            paper entitled "An attack on CRC-32 integrity checks of
            encrypted channels using CBC and CFB modes", which can be
            found at http://www.core-sdi.com/soft/ssh/ssh.pdf
            
            In order for this attack to succeed, an attacker must
            possess one or two known chipertext/plaintext pairs. This
            should not be difficult since every session starts with a
            greeting screen which is fixed and which can be
            determined. This also implies that an attacker must be
            somewhere along the session path in order to be able to
            sniff the session and collect corresponding chipertext.
            
            For further technical details, see
            http://www.core-sdi.com/soft/ssh/ssh.pdf.
            
    Traffic analysis
            This issue has been described in an analysis made by
            Solar Designer. It can be found at
            http://www.securityfocus.com/archive/1/169840, and is
            entitled "Passive Analysis of SSH (Secure Shell)
            Traffic".
            
            To exploit this vulnerability, an attacker must be able
            to capture packets. When sending a packet using the SSH
            protocol, it is padded to the next 8-byte boundary, but
            the exact len of the data (without the padding) is sent
            unencrypted.
            
            The timing between packets may yield additional
            information, such as the relative position of a letter on
            the keyboard, but that depends on overall jitter in the
            network and the typing habits of the person.
            
            For additional information, please see
            http://www.securityfocus.com/archive/1/169840.
            
    Key recovery in SSH protocol 1.5
            This has been discovered by CORE SDI S.A. and the paper
            describing it can be viewed at
            http://www.securityfocus.com/archive/1/161150. The
            subject line is "SSH protocol 1.5 session key recovery
            vulnerability".
            
            In order to exploit this vulnerability, an attacker must
            be able to sniff the SSH session and must be able to
            establish a connection to the SSH server. In order to
            recover the server key, an attcker must perform an
            additional 2^20+2^19=1572864 connections. Since the key
            has a lifespan of about an hour, this means that an
            attacker must perform around 400 connections per second.
            
            For further details, please conslut
            http://www.securityfocus.com/archive/1/161150.

Impact

    CRC-32 integrity check vulnerability
            By exploiting this protocol weakness, the attacker can
            insert arbitrary commands in the session after the
            session has been established.
            
    Traffic analysis
            This vulnerability exposes the exact lengths of the
            passwords used for login authentication. This is only
            applicable to an interactive session that is being
            established over the tunnel protected by SSH. This can
            significantly help an attacker in guessing the password
            using the brute force attack.
            
    Key recovery in SSH protocol 1.5
            This vulnerability may lead to the compromise of the
            session key. Once the session key is determined, the
            attacker can proceed to decrypt the stored session using
            any implementation of the crypto algorithm used. This
            will reveal all information in an unencrypted form.

Software Versions and Fixes

      Following software releases contains fixes for all
      vulnerabilities.
      
      For Catalyst 6000 switches all vulnerabilities are fixed in the
      following CatOS releases.

±--------±-------------------------------------------------------------+
| CatOS | 6.1(2.13), 6.2(0.111) and 6.3(0.7)PAN |
±--------±-------------------------------------------------------------+

      Each row of the table describes a release train and the
      platforms or products for which it is intended. If a given
      release train is vulnerable, then the earliest possible
      releases that contain the fix and the anticipated date of
      availability for each are listed in the "Rebuild", "Interim",
      and "Maintenance" columns. A device running any release in the
      given train that is earlier than the release in a specific
      column (less than the earliest fixed release) is known to be
      vulnerable, and it should be upgraded at least to the indicated
      release or a later version (greater than the earliest fixed
      release label).
      
      When selecting a release, keep in mind the following
      definitions:
      
          Maintenance
                  Most heavily tested and highly recommended release
                  of any label in a given row of the table.
                  
          Rebuild
                  Constructed from the previous maintenance or major
                  release in the same train, it contains the fix for
                  a specific defect. Although it receives less
                  testing, it contains only the minimal changes
                  necessary to effect the repair.
                  
          Interim
                  Built at regular intervals between maintenance
                  releases and receive less testing. Interims should
                  be selected only if there is no other suitable
                  release that addresses the vulnerability, and
                  interim images should be upgraded to the next
                  available maintenance release as soon as possible.
                  Interim releases are not available via
                  manufacturing, and usually they are not available
                  for customer download from CCO without prior
                  arrangement with the Cisco TAC.
                  
      In all cases, customers should exercise caution to be certain
      the devices to be upgraded contain sufficient memory and that
      current hardware and software configurations will continue to
      be supported properly by the new release. If the information is
      not clear, contact the Cisco TAC for assistance as shown in the
      following section.
      
      More information on IOS release names and abbreviations is
      available at http://www.cisco.com/warp/public/620/1.html.
      For PIX Firewall software, use the following table to determine
      affected and fixed software releases.

±-----±---------------------±-------------------------------------------+
|Train |Description of Image | Availability of Fixed Releases* |
| | or Platform | |
±-----±---------------------±------------------------±-----------------+
| 5.x-based Releases |Rebuild Interim** | Maintenance |
±----±----------------------±--------±--------------±-----------------+
| | | | 5.2(5)203 | 5.2.(6) |
| 5.2 | Early Deployment (ED) | |Available | Available in |
| | for all platforms | |through TAC | August |
±----±----------------------±--------±--------------±-----------------+
| | | |5.3(1)202 | 5.3.(1) |
| 5.3 | Early Deployment (ED) | |Available | Available in |
| | for all platforms | |through TAC | August |
±----±----------------------±--------±--------------±-----------------+
| 6.x-based Releases Rebuild | Interim** | Maintenance |
±----±----------------------±--------±--------------±-----------------+
| 6.0 | Early Deployment (ED) | | | 6.0(1) |
| | for all platforms | | | Available |
±----±----------------------±--------±--------------±-----------------+

      For Cisco IOS, use the following table to determine affected
      and fixed software releases.

±--------------±---------------±----------------------------------------+
| | Description of | |
| Train | Image or | Availability of Fixed Releases* |
| | Platform | |
±--------------±---------------±------------±-----------±-------------+
| 12.0-based Releases | Rebuild | Interim** | Maintenance |
±--------------±---------------±------------±-----------±-------------+
| |General | | | |
| 12.10S |deployment | | |12.0(18)S |
| |release for all | | |2001-July |
| |platforms | | | |
±--------------±---------------±------------±-----------±-------------+
| 12.1-based Releases | Rebuild | Interim** | Maintenance |
±--------------±---------------±------------±-----------±-------------+
| |General | |
| 12.1 |deployment | SSH not supported |
| |release for all | |
| |platforms | |
±--------------±---------------±----------------------------------------+
| 12.1AA |Dial support | SSH not supported |
±--------------±---------------±----------------------------------------+
| |Core/ISP | |
| 12.1CX |support: GSR, | SSH not supported |
| |RSP, c7200 | |
±--------------±---------------±----------------------------------------+
| 12.1DA |xDSL support: | SSH not supported |
| |6100, 6200 | |
±--------------±---------------±------------±-----------±-------------+
| |Cisco IOS | | | |
| |Software Release| | | |
| |12.1(1)DB | | | |
| 12.1DB |supports Cisco's| | | |
| |6400 Universal | | | |
| |Access | | | |
| |Concentrator | | | |
±--------------±---------------±------------±-----------±-------------+
| |Cisco IOS | | | |
| |Software Release| | | |
| |12.1(1)DC | | | |
| 12.1DC |supports Cisco's| | | |
| |6400 Universal | | | |
| |Access | | | |
| |Concentrator | | | |
±--------------±---------------±------------±-----------±-------------+
| |Core/ISP | | | |
| 12.1E |support: GSR, | | |12.1(8a)E |
| |RSP, c7200 | | |2001-Jul-09 |
±--------------±---------------±------------±-----------±-------------+
| |12.1EC is being | | | |
| |offered to allow| | | |
| |early support of| | | |
| |new features on | | | |
| |the uBR7200 | | | |
| 12.1EC |platform, as | |12.1(6.5)EC3| |
| |well as future | | | |
| |support for new | | | |
| |Universal | | | |
| |Broadband Router| | | |
| |headend | | | |
| |platforms. | | | |
±--------------±---------------±------------±-----------±-------------+
| 12.1EX |Catalyst 6000 | | |12.1(8a)E |
| |support | | |2001-Jul-09 |
±--------------±---------------±------------±-----------±-------------+
| |Cat8510c, | | | |
| 12.1EY |Cat8510m, | | |12.1(6)EY |
| |Cat8540c, | | | |
| |Cat8540m, LS1010| | | |
±--------------±---------------±------------±-----------±-------------+
| |Early Deployment| | | |
| 12.1EZ |(ED): special |12.1(6)EZ1 | | |
| |image | | | |
±--------------±---------------±------------±-----------±-------------+
| |Early | |
| |Deployment(ED): |Not Scheduled |
| 12.1T |VPN, Distributed| |
| |Director, ±----------------------------------------+
| |various |Upgrade recommended to 12.2(1b) |
| |platforms | |
±--------------±---------------±------------±-----------±-------------+
| |Early Deployment| | | |
| 12.1XA |(ED): limited | | | |
| |platforms | | | |
±--------------±---------------±------------±-----------±-------------+
| |Early Deployment| | | |
| 12.1XB |(ED): limited | | | |
| |platforms | | | |
±--------------±---------------±------------±-----------±-------------+
| |Early Deployment| | | |
| 12.1XC |(ED): limited | | | |
| |platforms | | | |
±--------------±---------------±------------±-----------±-------------+
| |Early Deployment|Not Scheduled |
| 12.1XD |(ED): limited ±----------------------------------------+
| |platforms |Upgrade recommended to 12.2(1b) |
±--------------±---------------±------------±-----------±-------------+
| |Early Deployment| | | |
| 12.1XE |(ED): limited | | | |
| |platforms | | | |
±--------------±---------------±------------±-----------±-------------+
| |Early Deployment| | | |
| 12.1XF |(ED): 811 and |12.1(2)XF4 | | |
| |813 (c800 |2001-July-09 | | |
| |images) | | | |
±--------------±---------------±------------±-----------±-------------+
| |Early Deployment| | | |
| 12.1XG |(ED): 800, 805, |12.1(5)XG5 | | |
| |820, and 1600 |2001-July-09 | | |
±--------------±---------------±------------±-----------±-------------+
| |Early Deployment|Not Scheduled |
| 12.1XH |(ED): limited ±----------------------------------------+
| |platforms |Upgrade recommended to 12.2(1b) |
±--------------±---------------±----------------------------------------+
| |Early Deployment|Not Scheduled |
| 12.1XI |(ED): limited ±----------------------------------------+
| |platforms |Upgrade recommended to 12.2(1b) |
±--------------±---------------±----------------------------------------+
| |Early Deployment|Not Scheduled |
| 12.1XJ |(ED): limited ±----------------------------------------+
| |platforms |Upgrade recommended to 12.1(5)YB4 |
±--------------±---------------±------------±-----------±-------------+
| |Early Deployment| |
| 12.1XK |(ED): limited | SSH not supported |
| |platforms | |
±--------------±---------------±------------±-----------±-------------+
| |Early Deployment|Not Scheduled |
| 12.1XL |(ED): limited ±----------------------------------------+
| |platforms |Upgrade recommended to 12.2(1b) |
±--------------±---------------±------------±-----------±-------------+
| |Short-lived | | | |
| 12.1XM |early deployment|12.1(4)XM4 | | |
| |release |2001-June-27 | | |
±--------------±---------------±------------±-----------±-------------+
| |Early Deployment| | | |
| 12.1XP |(ED): 1700 and |12.1(3)XP4 | | |
| |SOHO | | | |
±--------------±---------------±------------±-----------±-------------+
| |Short-lived |Not Scheduled |
| 12.1XQ |early deployment±----------------------------------------+
| |release |Upgrade recommended to 12.2(1b) |
±--------------±---------------±------------±-----------±-------------+
| |Short-lived | | | |
| 12.1XR |early deployment|12.1(5)XR2 | | |
| |release | | | |
±--------------±---------------±------------±-----------±-------------+
| |Short-lived | | | |
| 12.1XS |early deployment| | | |
| |release | | | |
±--------------±---------------±------------±-----------±-------------+
| |Early Deployment| | | |
| 12.1XT |(ED): 1700 |12.1(3)XT3 | | |
| |series | | | |
±--------------±---------------±------------±-----------±-------------+
| |Early Deployment| | | |
| 12.1XU |(ED): limited |12.1(5)XU1 | | |
| |platforms | | | |
±--------------±---------------±------------±-----------±-------------+
| |Short-lived | | | |
| 12.1XV |early deployment|12.1(5)XV3 | | |
| |release |2001-July | | |
±--------------±---------------±------------±-----------±-------------+
| |Short-lived | |
| 12.1XW |early deployment| SSH not supported |
| |release | |
±--------------±---------------±------------±-----------±-------------+
| |Short-lived | |
| 12.1XX |early deployment| SSH not supported |
| |release | |
±--------------±---------------±------------±-----------±-------------+
| |Short-lived | | | |
| 12.1XY |early deployment|12.1(5)XY6 | | |
| |release |2001-July | | |
±--------------±---------------±------------±-----------±-------------+
| |Short-lived | |
| 12.1XZ |early deployment| SSH not supported |
| |release | |
±--------------±---------------±------------±-----------±-------------+
| |Short-lived | | | |
| 12.1YA |early deployment| | | |
| |release | | | |
±--------------±---------------±------------±-----------±-------------+
| |Short-lived | | | |
| 12.1YB |early deployment|12.1(5)YB4 | | |
| |release | | | |
±--------------±---------------±------------±-----------±-------------+
| |Short-lived | | | |
| 12.1YC |early deployment|12.1(5)YC1 | | |
| |release | | | |
±--------------±---------------±------------±-----------±-------------+
| |Short-lived | | | |
| 12.1YD |early deployment|12.1(5)YD2 | | |
| |release |2001-June-25 | | |
±--------------±---------------±------------±-----------±-------------+
| |Short-lived | | | |
| 12.1YF |early deployment|12.1(5)YF2 | | |
| |release | | | |
±--------------±---------------±------------±-----------±-------------+
| 12.2-based Releases | Rebuild | Interim** | Maintenance |
±--------------±---------------±------------±-----------±-------------+
| |General | | | |
| 12.2 |deployment |12.2(1b) |12.2(1.1) |12.2(3) |
| |release for all | | |2001-August |
| |platforms | | | |
±--------------±---------------±------------±-----------±-------------+
| |General | | | |
| 12.2T |deployment | |12.2(2.2)T | |
| |release for all | | | |
| |platforms | | | |
±--------------±---------------±------------±-----------±-------------+
| 12.2XA |SPLOB | | |12.2(2)XA |
| | | | |2001-July-02 |
±--------------±---------------±------------±-----------±-------------+
| |Short-lived | | | |
| 12.2XD |early deployment|12.2(1)XD1 | | |
| |release | | | |
±--------------±---------------±------------±-----------±-------------+
| |Short-lived | | | |
| 12.2XE |early deployment| | |12.2(1)XE |
| |release | | | |
±--------------±---------------±------------±-----------±-------------+
| |Short-lived | | | |
| 12.2XH |early deployment| | |12.2(1)XH |
| |release | | |2001-June-25 |
±--------------±---------------±------------±-----------±-------------+
| |Short-lived | | | |
| 12.2XQ |early deployment| | |12.2(1)XQ |
| |release | | |2001-June-23 |
±--------------±---------------±------------±-----------±-------------+
| Notes |
±-------------------------------------------------------------------------+
| * All dates are estimated and subject to change. |
| |
| ** Interim releases are subjected to less rigorous testing than regular |
| maintenance releases, and may have serious bugs. |
±-------------------------------------------------------------------------+

Obtaining Fixed Software

      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 Web site at
      http://www.cisco.com.
      
      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 directly 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: [email protected]
        
      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.

Workarounds

      There are no workarounds for these vulnerabilities.

Exploitation and Public Announcements

      All three vulnerabilities are publicly known. Please see the
      Details section for the original announcements.
      
      The Cisco PSIRT is not aware of malicious use of the
      vulnerabilities described in this advisory.

Status of This Notice: INTERIM

      This is an interim security advisory. Cisco anticipates issuing
      updated versions of this notice at irregular intervals as there
      are material changes in the facts, and will continue to update
      this notice as necessary. The reader is warned that this notice
      may contain inaccurate or incomplete information. Although
      Cisco cannot guarantee the accuracy of all statements in this
      notice, all of the facts have been checked to the best of our
      ability. Cisco anticipates issuing monthly updates of this
      notice until it reaches FINAL status.
      
      A standalone copy or paraphrase of the text of this security
      advisory that omits the distribution URL in the following
      section is an uncontrolled copy, and may lack important
      information or contain factual errors.

Distribution

      This notice will be posted on Cisco's Worldwide Web site at
      http://www.cisco.com/warp/public/707/SSH-multiple-pub.html.
      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:
      
      + [email protected]
      + [email protected]
      + [email protected] (includes CERT/CC)
      + [email protected]
      + comp.dcom.sys.cisco
      + [email protected]
      + Various internal Cisco mailing lists
        
      Future updates of this notice, if any, will be placed on
      Cisco's Worldwide Web server, but may or may not be actively
      announced on mailing lists or newsgroups. Users concerned about
      this problem are encouraged to check the URL given above for
      any updates.

Revision History

      Revision 1.0 2001-June-27 08:00 UTC -0800 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 Web site at
      http://www.cisco.com/warp/public/707/sec_incident_response.
      shtml. This includes instructions for press inquiries regarding
      Cisco security notices.
      
      For a list of all advisories please visit
      http://www.cisc.com/warp/public/707/advisory.html page.
        __________________________________________________________
      
      This notice is Copyright 2000 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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