[nsp] Cisco Security Advisory: Cisco OpenSSL Implementation Vulnerability

Wed Mar 17 09:16:32 EST 2004

   A new vulnerability in the OpenSSL implementation for SSL
   has been announced on March 17, 2004.

   An affected network device running an SSL server based on an affected
   OpenSSL implementation may be vulnerable to a Denial of Service (DoS)
   attack. There are workarounds available to mitigate the effects of this
   vulnerability on Cisco products in the workaround section of this
   advisory. Cisco is providing fixed software, and recommends that customers
   upgrade to it when it is available.

   This advisory will be posted at
   http://www.cisco.com/warp/public/707/cisco-sa-20040317-openssl.shtml.

Affected Products

   The following products have their SSL implementation based on the OpenSSL
   code and are affected by this vulnerability.

     * Cisco IOS 12.1(11)E and later in the 12.1E release train. Only crypto
       images (56i and k2) are vulnerable for the Cisco 7100 and 7200 Series
       Routers.
     * Cisco IOS 12.2SY release train. Only crypto images (k8, k9 and k91)
       are vulnerable for the Cisco Catalyst 6500 Series and Cisco 7600
       Series Routers.
     * Cisco PIX Firewall
     * Cisco Firewall Services Module (FWSM) for the Cisco Catalyst 6500
       Series and Cisco 7600 Series routers
     * Cisco MDS 9000 Series Multilayer Switch
     * Cisco Content Service Switch (CSS) 11000 series
     * Cisco Global Site Selector (GSS) 4480
     * CiscoWorks Common Services (CWCS) version 2.2 and CiscoWorks Common
       Management Foundation (CMF) version 2.1
     * Cisco Access Registrar (CAR)

   The following products have their SSL implementation based on the OpenSSL
   code and are not affected by this vulnerability.

     * Cisco Secure Intrusion Detection System (NetRanger) appliance. This
       includes the IDS-42xx appliances, NM-CIDS and WS-SVS-IDSM2.
     * Cisco SN 5428 and SN 5428-2 Storage Router
     * Cisco CNS Configuration Engine
     * Cisco Network Analysis Modules (NAM) for the Cisco Catalyst 6000 and
       6500 Series switches and Cisco 7600 Series routers
     * Cisco SIP Proxy Server (SPS)
     * CiscoWorks 1105 Hosting Solution Engine (HSE)
     * CiscoWorks 1105 Wireless LAN Solution Engine (WLSE)
     * Cisco Ethernet Subscriber Solution Engine (ESSE)

   The following products, which implement SSL, are not affected by this
   vulnerability.

     * Cisco VPN 3000 Series Concentrators

   CatOS does not implement SSL and is not vulnerable.

   No other Cisco products are currently known to be affected by this
   vulnerability. This vulnerability is still being actively investigated
   across Cisco products and status of some products has still not been
   determined.

Details

   Secure Sockets Layer (SSL), is a protocol used to encrypt the data
   transferred over an TCP session. SSL in Cisco products is mainly used by
   the HyperText Transfer Protocol Secure (HTTPS) web service for which the
   default TCP port is 443. The affected products, listed above, are only
   vulnerable if they have the HTTPS service enabled and the access to the
   service is not limited to trusted hosts or network management
   workstations.

   To check if the HTTPS service is enabled one can do the following:

    1. Check the configuration on the device to verify the status of the
       HTTPS service.
    2. Try to connect to the device using a standard web browser that
       supports SSL using a URL similar to https://ip_address_of_device/.
    3. Try and connect to the default HTTPS port, TCP 443, using Telnet.
       telnet ip_address_of_device 443. If the session connects the service
       is enabled and accessible.

   Testing by the OpenSSL development team has uncovered a null-pointer
   assignment in the do_change_cipher_spec() function. A remote attacker
   could perform a carefully crafted SSL/TLS handshake against a server that
   used the OpenSSL library in such a way as to cause OpenSSL to crash. This
   crash on many Cisco products would cause the device to reload. Repeated
   exploitation of this vulnerability would result in a Denial of Service
   (DoS) attack on the device.

   Another flaw was also discovered in the SSL/TLS handshaking code when
   using Kerberos ciphersuites. A remote attacker could perform a carefully
   crafted SSL/TLS handshake against a server configured to use Kerberos
   ciphersuites in such a way as to cause OpenSSL to crash. None of the Cisco
   OpenSSL implementations are known to use Kerberos ciphersuites and are
   therefore not affected by this second vulnerability.

   A third vulnerability described in the NISCC advisory is a bug in older
   versions of OpenSSL, versions before 0.9.6d, that can also lead to a
   Denial of Service attack. None of the Cisco OpenSSL implementations are
   known to be affected by this older OpenSSL issue.

   More information on the OpenSSL vulnerability is available at
   http://www.openssl.org/news/secadv_20040317.txt .

     * Cisco IOS - All 12.1(11)E and later IOS software crypto (56i and k2)
       image releases in the 12.1E release train for the Cisco 7100 and 7200
       Series Routers are affected by this vulnerability. All IOS software
       crypto (k8, k9, and k91) image releases in the 12.2SY release train
       for the Cisco Catalyst 6500 Series and Cisco 7600 Series Routers are
       affected by this vulnerability. The SSH implementation in IOS is not
       dependent on any OpenSSL code. SSH implementations in IOS do not
       handle certificates, yet, and therefore do not use any SSL code for
       SSH. OpenSSL in 12.1E and 12.2SY release trains is only used for
       providing the HTTPS and VPN Device Manager (VDM) services. This
       vulnerability is documented in the Cisco Bug Toolkit (registered
       customers only) as Bug ID CSCee00041. The HTTPS web service, that uses
       the OpenSSL code, on the device is disabled by default. The no ip http
       secure-server command may be used to disable the HTTPS web service on
       the device, if required. The SSH and IPSec services in IOS are not
       vulnerable to this vulnerability.
     * Cisco PIX Firewall - PIX 6.x releases are affected by this
       vulnerability. PIX 5.x releases do not contain any SSL code and are
       not vulnerable. This vulnerability is documented in the Cisco Bug
       Toolkit (registered customers only) as Bug ID CSCed90672.
     * Cisco Firewall Services Module (FWSM) for the Cisco Catalyst 6500
       Series and Cisco 7600 Series routers - This vulnerability is
       documented in the Cisco Bug Toolkit (registered customers only) as Bug
       ID CSCee02055.
     * Cisco MDS 9000 Series Multilayer Switches - This vulnerability is
       documented in the Cisco Bug Toolkit (registered customers only) as Bug
       ID CSCed96246.
     * Cisco Content Service Switch (CSS) 11000 series - WebNS version 6.x
       and 7.x are affected by this vulnerability. WebNS version 5.x is not
       vulnerable to the OpenSSL vulnerabilities. This vulnerability is
       documented in the Cisco Bug Toolkit (registered customers only) as Bug
       ID CSCee01234 for SCM and is documented in the Cisco Bug Toolkit
       (registered customers only) as Bug ID CSCee01240 for the SSL module.
     * Cisco Global Site Selector (GSS) 4480 - This vulnerability is
       documented in the Cisco Bug Toolkit (registered customers only) as Bug
       ID CSCee01057.
     * CiscoWorks Common Services (CWCS) version 2.2 and CiscoWorks Common
       Management Foundation (CMF) version 2.1 - This vulnerability is
       documented in the Cisco Bug Toolkit (registered customers only) as Bug
       ID CSCsa13748.
     * Cisco Access Registrar (CAR) - This vulnerability is documented in the
       Cisco Bug Toolkit (registered customers only) as Bug ID CSCee01956.

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

Impact

   An affected network device running an SSL server based on the OpenSSL
   implementation may be vulnerable to a Denial of Service (DoS) attack.

Software Versions and Fixes

     * Cisco IOS -

       +----------------------------------------+
       |Release|  Fixed Releases  |Availability |
       | Train |                  |             |
       |-------+------------------+-------------|
       |12.2SY |12.2(14)SY4       |March 25     |
       |-------+------------------+-------------|
       |       |12.1(13)E14       |April 8      |
       |12.1E  |12.1.(19)E7       |April 8      |
       |       |12.1(20)E3        |April 26     |
       +----------------------------------------+

     * Cisco PIX Firewall - The vulnerability is fixed in software releases
       6.0(4)102, 6.1(5)102, 6.2(3)107, and 6.3(3)124. These engineering
       builds may be obtained by contacting the Cisco Technical Assistance
       Center (TAC). TAC Contact information is given in the Obtaining Fixed
       Software section below.
     * Cisco Firewall Services Module (FWSM) for the Cisco Catalyst 6500
       Series and Cisco 7600 Series routers - The vulnerability is fixed in
       software release 1.1.3(14) which will be available by Monday, 22 of
       March, 2004. This engineering builds may be obtained by contacting the
       Cisco Technical Assistance Center (TAC). TAC Contact information is
       given in the Obtaining Fixed Software section below.
     * Cisco MDS 9000 Series Multilayer Switches - No fixed software release
       or software availability date has been determined yet.
     * Cisco Content Service Switch (CSS) 11000 series -No fixed software
       release or software availability date has been determined yet.
     * Cisco Global Site Selector (GSS) 4480 - No fixed software release or
       software availability date has been determined yet.
     * CiscoWorks Common Services (CWCS) version 2.2 and CiscoWorks Common
       Management Foundation (CMF) version 2.1 - No fixed software release or
       software availability date has been determined yet.
     * Cisco Access Registrar (CAR) - The vulnerability is fixed in software
       release 3.5.0.12 which will be available by Friday, 26 of March, 2004.

Obtaining Fixed Software

   Cisco is offering free software upgrades to address this vulnerability 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.shtml.

   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/tacpage/sw-center. 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 a 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 obtaining the software
   upgrade(s).

   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) using the contact information listed below. In
   these cases, customers are entitled to obtain a free upgrade to a later
   version of the same release or as indicated by the applicable corrected
   software version in the Software Versions and Fixes section (noted above).

   Cisco 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.com

   See http://www.cisco.com/warp/public/687/Directory/DirTAC.shtml for
   additional TAC contact information, including special localized telephone
   numbers and instructions and e-mail addresses for use in various
   languages.

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

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

Workarounds

   The Cisco PSIRT recommends that affected users upgrade to a fixed software
   version of code as soon as it is available.

     * Restrict access to the HTTPS server on the network device. Allow
       access to the network device only from trusted workstations by using
       access lists / MAC filters that are available on the affected
       platforms.
     * Disable the SSL server / service on the network device. This
       workaround must be weighed against the need for secure communications
       with the vulnerable device.

Exploitation and Public Announcements

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

   This vulnerability was reported to Cisco PSIRT by NISCC. NISCC has
   documented this vulnerability at
   http://www.uniras.gov.uk/vuls/2004/224012/index.htm .

Status of This Notice: INTERIM

   This is an interim 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 may 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-20040317-openssl.shtml .

   In addition to worldwide web posting, a text version of this notice is
   clear-signed with the Cisco PSIRT PGP key having the fingerprint 8C82 5207
   0CA9 ED40 1DD2 EE2A 7B31 A8CF 32B6 B590 and is posted to the following
   e-mail and Usenet news recipients.

     * cust-security-announce at cisco.com
     * first-teams at first.org (includes CERT/CC)
     * bugtraq at securityfocus.com
     * vulnwatch at vulnwatch.org
     * cisco at spot.colorado.edu
     * cisco-nsp at puck.nether.net
     * full-disclosure at lists.netsys.com
     * comp.dcom.sys.cisco at newsgate.cisco.com

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

Revision History

   +------------------------------------------+
   |Revision 1.0|2004-March-17|Initial        |
   |            |             |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 advisory is copyright 2004 by Cisco Systems, Inc. This advisory may
   be redistributed freely after the release date given at the top of the
   text, provided that redistributed copies are complete and unmodified,
   including all date and version information.

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