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             AUSCERT External Security Bulletin Redistribution

              ESB-2005.0954 -- Sun Alert Notification 101974
            OpenSSL May Allow an Agent to Force a Rollback to a
                      Cryptographically Weak Protocol
                              1 December 2005

===========================================================================

        AusCERT Security Bulletin Summary
        ---------------------------------

Product:           OpenSSL
Publisher:         Sun Microsystems
Operating System:  Solaris
Impact:            Reduced Security
Access:            Remote/Unauthenticated
CVE Names:         CAN-2005-2969

Ref:               ESB-2005.0818

Original Bulletin: http://sunsolve.sun.com/search/printfriendly.do?assetkey=1-26-101974-1

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Sun(sm) Alert Notification
     * Sun Alert ID: 101974
     * Synopsis: OpenSSL (see openssl(5)) May Allow an Agent to Force a
       Rollback to a Cryptographically Weak Protocol Version
     * Category: Security
     * Product: Solaris 10 Operating System
     * BugIDs: 6332476
     * Avoidance: Patch
     * State: Resolved
     * Date Released: 11-Oct-2005, 29-Nov-2005
     * Date Closed: 29-Nov-2005
     * Date Modified: 14-Oct-2005, 29-Nov-2005

1. Impact

   A vulnerability in the OpenSSL (see openssl(5)) toolkit may allow
   active protocol-version rollback attacks, where an attacker acting as
   a "man in the middle" can force a client and a server to negotiate the
   SSL 2.0 protocol even if these parties both support SSL 3.0 or TLS
   1.0. The SSL 2.0 protocol is known to have severe cryptographic
   weaknesses and is supported as a fallback only.

   This issue is described in the following OpenSSL Advisory:
   http://www.openssl.org/news/secadv_20051011.txt

   and referenced in CAN-2005-2969
   at: http://cve.mitre.org/cgi-bin/cvename.cgi?name=CAN-2005-2969

2. Contributing Factors

   This issue can occur in the following releases:

   SPARC Platform
     * Solaris 10 without patch 121229-01

   x86 Platform
     * Solaris 10 without patch 121230-01

   Note: Solaris 8 and 9 do not include OpenSSL toolkit, and therefore
   are not vulnerable to this issue.

   Applications that use the option SSL_OP_MSIE_SSLV2_RSA_PADDING (see
   SSL_CTX_set_options(3)) are affected. This option is implied by use of
   SSL_OP_ALL, which is intended to work around various bugs in
   third-party software that might prevent interoperability.

   The vulnerability occurs only if the old protocol version SSL 2.0 is
   enabled both in an OpenSSL server and in any of the clients
   (OpenSSL-based or not) connecting to it.

3. Symptoms

   There are no reliable symptoms that would indicate the described issue
   has been exploited. 

4. Relief/Workaround

   To work around the described issue:

   If Apache or Apache2 in Solaris 10 are configured with SSL service on
   port 443 (https), the following command can be used to check if the
   SSL 2.0 protocol is enabled at the server:
    $ /usr/sfw/bin/openssl s_client -ssl2 -connect <hostname>:443 -state -debug

   If the above command produces output, then SSLv2 is enabled and can be
   disabled in the Apache and Apache2 web servers as follows:

   1. As a privileged user, edit the following file:
    Apache: /etc/apache/httpd.conf
    Apache2: /etc/apache2/ssl.conf

   2. Modify the line which begins with:
    SSLCipherSuite

   to change the string '+SSLv2' to '!SSLv2'.

   3. Restart the Apache web server:
    Apache: # /usr/apache/bin/apachectl restart
    Apache2: svcadm restart apache2


5. Resolution

   This issue is addressed in the following releases:

   SPARC Platform
     * Solaris 10 with patch 121229-01 or later

   x86 Platform
     * Solaris 10 with patch 121230-01 or later

Change History

   14-Oct-2005:
     * Updated Relief/Workaround

   29-Nov-2005:
     * Updated Contributing Factors and Resolution sections, re-release
       as Resolved

   This Sun Alert notification is being provided to you on an "AS IS"
   basis. This Sun Alert notification may contain information provided by
   third parties. The issues described in this Sun Alert notification may
   or may not impact your system(s). Sun makes no representations,
   warranties, or guarantees as to the information contained herein. ANY
   AND ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION
   WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, OR
   NON-INFRINGEMENT, ARE HEREBY DISCLAIMED. BY ACCESSING THIS DOCUMENT
   YOU ACKNOWLEDGE THAT SUN SHALL IN NO EVENT BE LIABLE FOR ANY DIRECT,
   INDIRECT, INCIDENTAL, PUNITIVE, OR CONSEQUENTIAL DAMAGES THAT ARISE
   OUT OF YOUR USE OR FAILURE TO USE THE INFORMATION CONTAINED HEREIN.
   This Sun Alert notification contains Sun proprietary and confidential
   information. It is being provided to you pursuant to the provisions of
   your agreement to purchase services from Sun, or, if you do not have
   such an agreement, the Sun.com Terms of Use. This Sun Alert
   notification may only be used for the purposes contemplated by these
   agreements.

   Copyright 2000-2005 Sun Microsystems, Inc., 4150 Network Circle, Santa
   Clara, CA 95054 U.S.A. All rights reserved

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