AusCERT - ESB-2006.0944 -- [Solaris] -- Security Vulnerability With RSA Signatures Affects Solaris WAN Boot

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ESB-2006.0944 -- [Solaris] -- Security Vulnerability With RSA Signatures Affects Solaris WAN Boot
Date: 13 November 2007
References: ESB-2006.0728 ESB-2007.0271 ESB-2007.0473

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             AUSCERT External Security Bulletin Redistribution

                        ESB-2006.0944 -- [Solaris]
    Security Vulnerability With RSA Signatures Affects Solaris WAN Boot
                             14 November 2007

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

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

Product:              Solaris
Publisher:            Sun Microsystems
Operating System:     Solaris 9 and 10
Impact:               Inappropriate Access
Access:               Remote/Unauthenticated
CVE Names:            CVE-2006-4339 CVE-2006-2937 CVE-2006-2940

Ref:                  ESB-2007.0473
                      ESB-2007.0271
                      ESB-2006.0728

Original Bulletin:    
   http://sunsolve.sun.com/search/printfriendly.do?assetkey=1-26-102759-1

Revision History:  November 14 2007: Updated the Impact section to include 
                                     additional related CVEs. 
                                     Updated the Relief/Workaround to state 
                                     the absence of a workaround to avoid 
                                     the Denial of Service Vulnerablilty. 
                                     Updated the Resolution section to 
                                     include the fix for Solaris 9.
                       July 30 2007: Patches available for SUNWcry package
                   December 27 2006: Solaris 10 patches now available
                   December 27 2006: Initial Release

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Sun(sm) Alert Notification
     * Sun Alert ID: 102759
     * Synopsis: Security Vulnerabilities in OpenSSL Affect Solaris WAN
       Boot
     * Category: Security
     * Product: Solaris 9 Operating System, Solaris 10 Operating System
     * BugIDs: 6467218, 6476279
     * Avoidance: Patch, Workaround
     * State: Resolved
     * Date Released: 22-Dec-2006, 09-Nov-2007
     * Date Closed: 09-Nov-2007
     * Date Modified: 24-Apr-2007, 23-Jul-2007, 09-Nov-2007

1. Impact

   Multiple vulnerabilities in the OpenSSL product impact the Solaris WAN
   boot software.

   An RSA signature forgery vulnerability may allow an untrusted server
   or client to present a forged identity to the other party during
   remote software installation when SSL is in use with certain types of
   certificates. This would allow the security restrictions of that SSL
   configuration to be circumvented.

   Additionally, security vulnerabilities in the ASN.1 parser
   implementation and public key handling in the OpenSSL library may
   allow a user who is running a client system that is able to connect to
   a WAN Boot installation server to cause a Denial Of Service (DoS) to
   that server. This could prevent the server from providing service to
   WAN Boot clients. Clients connecting to an untrusted server may also
   be impacted by this issue.

   Note that the WAN Boot software uses a static version of the OpenSSL
   libraries, meaning that the Solaris 10 resolution for Sun Alert
   102744, which corrects applications dynamically linking to the Solaris
   OpenSSL libraries, is not sufficient to resolve this issue for the WAN
   Boot software. This Sun Alert will describe the full impact and
   resolution for the WAN Boot software.

   These issues are also described in the following documents:

   CERT VU#845620 at http://www.kb.cert.org/vuls/id/845620

   CVE-2006-4339 at
   http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2006-4339

   http://www.openssl.org/news/secadv_20060928.txt

   CVE-2006-2937 at
   http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2006-2937

   CVE-2006-2940 at
   http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2006-2940

   Note: This Sun Alert is specific to the Solaris WAN Boot software.
   Multiple Sun products are affected by the RSA signature forgery issue;
   for more details please see Sun Alert 102648 at

   http://sunsolve.sun.com/search/document.do?assetkey=1-26-102648-1

2. Contributing Factors

   This issue can occur in the following releases:

   SPARC Platform
     * Solaris 9 (12/03 or later) without patch 117123-08
     * Solaris 10 without patch 121229-02

   x86 Platform
     * Solaris 9 (12/03 or later) without patch 122715-02
     * Solaris 10 without patch 121230-02

   Notes:

   1. Solaris 8 does not include The WAN boot software, and is not
   impacted by this issue.

   2. WAN Boot only supports installation to SPARC-based clients.

   3. A WAN Boot remote installation will only be affected by this issue
   if it is configured to download the installation data by a secure SSL
   connection for either:

   a) the initial stages of the installation when the client downloads
   its boot environment from the server

   or

   b) the latter stages of the installation when the JumpStart
   configuration and the installation media are downloaded in the form of
   Solaris Flash archives (which may come from a different server than
   that mentioned in item 'a' above).

   Whether or not SSL is used in these ways during the WAN Boot
   installation process is determined by the configuration which is
   maintained by the server and distributed to the client during the
   installation. The server may maintain different configurations for
   different clients, each of which may or may not use SSL.

   To determine if SSL will be used during the initial stages of the
   installation of a specific client according to the configuration
   maintained on the server, the wanboot.conf(4) file that is stored on
   the server and is associated with that client can be checked (taking
   into account that there may be multiple wanboot.conf files on the
   system for different clients or groups of clients). For example, to
   confirm if server or client authentication is in use for a certain
   client installation, a command such as the following can be used:
    # grep _authentication /etc/netboot/<optional_net_and_client_id>/wanboot.co
nf
    server_authentication=yes
    client_authentication=yes

   To determine if SSL is used to download the JumpStart configuration
   the system configuration file associated with the client being
   installed should be checked. The location and name of this file will
   be determined by the 'system_conf' setting in the wanboot.conf file.
   For example:
    # grep https: /etc/netboot/<name_of_system_configuration_file>
    SsysidCF=https://192.186.1.1/flash/
    SjumpsCF=https://192.186.1.1/flash/

   To determine if SSL will be used to download the Solaris Flash
   archives, the JumpStart configuration which is stored on the
   installation server at a location configured in the system
   configuration file can be checked using a command such as the
   following:
    # grep archive_location <path_to_jumpstart_config>/profile
    archive_location https://192.186.1.1/flash_archive.flar

   If the returned URL begins with 'https:' the flash archive will be
   downloaded using SSL.

   The RSA signature forgery issue only affects signatures which are made
   using keys based on the RSA algorithm with an exponent of 3. Tools
   such as openssl(1) (which is shipped with Solaris 10, Solaris 9 does
   not include a tool which can be used for this purpose) can be used to
   determine the algorithm and exponent setting associated with a certain
   key. The exact method will depend on the tool and the configuration.
   For example, to display the details of a certificate which is stored
   in a PKCS12 formatted file (as passed to the wanbootutil(1M)'s
   'pkcs12split' subcommand during the initial WAN Boot setup), the
   openssl application could be used in the following way:
    $ openssl pkcs12 -in <pkcs12-file> -nokeys | openssl x509 -text | egrep 'Ex
ponent:|Public Key Algorithm:'
    Enter Import Password:
    MAC verified OK
            Public Key Algorithm: rsaEncryption
                Exponent: 65537 (0x10001)

   Some parts of the WAN Boot software that are affected by this
   vulnerability may be installed independently from the standard
   locations. For example, the 'wanboot-cgi' program will be installed in
   a location where it can be served by the web server software that is
   installed on the server host. In addition, clients which do not
   support WAN Boot installations from the OBP may be booting from a
   CDROM, from where they will acquire the 'wanboot' application. All of
   these extra items will need to be updated for the resolution to be
   fully active.

3. Symptoms

   There are no symptoms that would indicate that these vulnerabilities
   have been exploited to forge RSA signatures. If the issues mentioned
   above have been exploited to cause a Denial of Service, processes
   belonging to the affected applications will be consuming unusually
   large amounts of CPU time and memory, and other applications running
   on the system may be slow or unresponsive.

   For the client side this means it could hang while booting or
   performing installation via WAN boot.

   Commands such as prstat(1M) can be used to determine the utilization
   of system resources on the server side, for example:
    $ prstat -s cpu
    [...]

    $ prstat -s size
    [...] 

4. Relief/Workaround

   To workaround the RSA signature verification vulnerability it is
   possible that the certificates in use can be replaced with
   certificates which use an exponent other than 3. For more details
   about how this can be done, consult the documentation which
   accompanies the software that is used to create the certificates, or
   consult the organization which provides the certificates.

   There is no workaround to prevent these issues from being exploited to
   cause a Denial of Service.

5. Resolution

   This issue is addressed in the following releases:

   SPARC Platform
     * Solaris 9 (12/03 or later) with patch 117123-08 or later
     * Solaris 10 with patch 121229-02 or later

   x86 Platform
     * Solaris 9 (12/03 or later) with patch 122715-02
     * Solaris 10 with patch 121230-02 or later

Change History

   24-Apr-2007:
     * Updated Contributing Factors and Resolution sections

   23-Jul-2007:
     * Updated Resolution section

   09-Nov-2007:
     * Update Impact, Contributing Factors, Relief/Workaround, and
       Resolution
     * State: 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 2000-2006 Sun Microsystems, Inc., 4150 Network Circle, Santa
   Clara, CA 95054 U.S.A. All rights reserved


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