AusCERT - ESB-2005.0477 -- Sun Alert Notification 101783 -- Security Vulnerability in Samba's "ms_fnmatch()" Function May Result in a Denial of Service (DoS)

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ESB-2005.0477 -- Sun Alert Notification 101783 -- Security Vulnerability in Samba's "ms_fnmatch()" Function May Result in a Denial of Service (DoS)
Date: 19 October 2006
References: ESB-2004.0714

Click here for printable version
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             AUSCERT External Security Bulletin Redistribution

              ESB-2005.0477 -- Sun Alert Notification 101783
         Security Vulnerability in Samba's "ms_fnmatch()" Function
                  May Result in a Denial of Service (DoS)
                               19 October 2006 

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

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

Product:           Samba
Publisher:         Sun Microsystems
Operating System:  Solaris 10
                   Solaris 9
Impact:            Denial of Service
Access:            Existing Account
CVE Names:         CAN-2004-0930

Ref:               ESB-2004.0714

Original Bulletin:
http://sunsolve.sun.com/search/printfriendly.do?assetkey=1-26-101783-1

Revision History:  October 19 2006: Updated Contributing Factors and
                                    Resolution sections
                   June 27 2005: Initial Release

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Sun(sm) Alert Notification
     * Sun Alert ID: 101783
     * Synopsis: Security Vulnerability in Samba's "ms_fnmatch()"
       Function May Result in a Denial of Service (DoS)
     * Category: Security
     * Product: Solaris 9 Operating System, Solaris 10 Operating System
     * BugIDs: 6218964
     * Avoidance: Patch, Workaround
     * State: Resolved
     * Date Released: 23-Jun-2005, 17-Oct-2006
     * Date Closed: 17-Oct-2006
     * Date Modified: 24-Jun-2005, 17-Oct-2006

1. Impact

   A security vulnerability in Samba's "ms_fnmatch()" function may allow
   a remote unprivileged user the ability to create a Denial of Service
   (DoS) by causing excessive CPU consumption via a Samba request that
   contains multiple wildcard characters.

   This issue is referenced in the following document:
     * CAN-2004-0930 at:
       http://www.cve.mitre.org/cgi-bin/cvename.cgi?name=CAN-2004-0930

2. Contributing Factors

   This issue can occur in the following releases:

   SPARC Platform
     * Solaris 9 without patch 114684-05
     * Solaris 10 without patch 119757-01

   x86 Platform
     * Solaris 9 without patch 114685-05
     * Solaris 10 without patch 119758-01

   Note: Solaris 7 and Solaris 8 do not include the Samba software and
   are not affected by this issues. Sun does include Samba on the Solaris
   Companion CD for Solaris 8 as an unsupported package which installs to
   "/opt/sfw" and is vulnerable to this issue. Sites using the freeware
   version of Samba from the Solaris Companion CD will need to upgrade to
   a later version from Samba.org.

   The described issue only occurs if both of the following conditions
   are true:
    1. The system is configured as a Samba server.
    2. The version of Samba installed is 2.x through 3.0.7

   To determine if a system is configured as a Samba server, use the
   following command to check for the presence of the smb.conf(4) file:
    % ls -l /etc/sfw/smb.conf
    -rw-r--r-- 1 root other 11665 Sep 28 16:37 /etc/sfw/smb.conf

   If the output is similar to that shown above, the system is configured
   as a Samba server.

   To determine the version of Samba installed on a system, the following
   command can be run:
    % /usr/sfw/sbin/smbd -V
    Version 3.0


3. Symptoms

   If the described issue occurs, the Samba server running on an impacted
   machine will consume more CPU cycles than normal, reducing the quality
   of service provided by the Samba server. In some circumstances the
   server may become entirely unresponsive. 

4. Relief/Workaround

   The Samba Server Security web page:
    http://www.samba.org/samba/docs/server_security.html

   documents several ways to restrict access to Samba servers and further
   protect Samba servers. Sites may consider applying the advice there
   even for patched systems.

   Until patches are available or can be applied, sites may consider
   downloading and compiling Samba 3.0.8 or higher from the Samba site
   at:
    http://www.samba.org

   as an interim workaround. Note however that the downloaded Samba
   software is not supported by Sun.

5. Resolution

   This issue is addressed in the following releases:

   SPARC Platform
     * Solaris 9 with patch 114684-05 or later
     * Solaris 10 with patch 119757-01 or later

   x86 Platform
     * Solaris 9 with patch 114685-05 or later
     * Solaris 10 with patch 119758-01 or later

Change History

   24-Jun-2005:
     * Added note to Contributing Factors section

   17-Oct-2006:
     * State: Resolved
     * Updated Contributing Factors and Resolution sections

   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.

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