===================================================================== CERT-Renater Note d'Information No. 2009/VULN462 _____________________________________________________________________ DATE : 19/11/2009 HARDWARE PLATFORM(S) : / OPERATING SYSTEM(S) : Solaris 9, Solaris10, OpenSolaris running Samba versions prior to 3.0.37. ====================================================================== http://sunsolve.sun.com/search/printfriendly.do?assetkey=1-66-271069-1 ______________________________________________________________________ Two Security Vulnerabilities in SAMBA(7) May Allow Unauthorized Access to the Remote Root Filesystem or May Lead to a Denial of Service (DoS) Condition _________________________________________________________________ Category : Security Release Phase : Workaround Bug Id : 6888097 Product : Samba 3.0.36 Solaris 9 Operating System Solaris 10 operating System OpenSolaris Date of Workaround Release : 17-Nov-2009 Two Security Vulnerabilities in SAMBA(7) May Allow Unauthorized Access to the Remote Root Filesystem or May Lead to a Denial of Service (DoS) Condition 1. Impact Two security vulnerabilities in SAMBA(7) may result in one or both of the following issues: 1. A remote unprivileged user with a valid SAMBA account may gain unauthorized access to the remote root file system. This issue is referenced in the following CVE document: http://www.samba.org/samba/security/CVE-2009-2813.html 2. A remote unprivileged user on an authenticated SAMBA connection may cause a Denial of Service (DoS) condition via specially crafted SMB requests. This issue is referenced in the following CVE document: http://www.samba.org/samba/security/CVE-2009-2906.html 2. Contributing Factors These issues can occur in the following releases: SPARC Platform * Solaris 9 * Solaris 10 without patch 119757-17 * OpenSolaris based upon builds snv_01 through 126 X86 Platform * Solaris 9 * Solaris 10 without patch 119758-17 * OpenSolaris based upon builds snv_01 through 126 running SAMBA software 3.0.36 and earlier. Notes: 1. Solaris 8 does not include the SAMBA software and is not affected by this issue. 2. OpenSolaris distributions may include additional bug fixes above and beyond the build from which it was derived. To determine the base build of OpenSolaris, the following command can be run: $ uname -v snv_125 3. These issues can only occur if the following conditions are true: - - The system is configured as a SAMBA server - - The version of SAMBA installed is earlier than 3.0.37 To determine if a system is configured as a SAMBA server, the following command can be run to check for processes related to SAMBA: % ps -ef | grep mbd root 317 1 0 May 26 ? 0:01 /usr/sfw/sbin/smbd -D root 325 317 0 May 26 ? 0:00 /usr/sfw/sbin/smbd -D root 314 1 0 May 26 ? 0:27 /usr/sfw/sbin/nmbd -D root 28369 17382 0 23:17:46 pts/2 0:00 grep mbd If the output shows "smbd" or "nmbd" running as a daemon (with the -D parameter), the system is configured as a SAMBA server. To determine the SAMBA version, the following command can be run: $ /usr/sfw/sbin/smbd -V Version 3.0.28 4. The issue described in CVE-2009-2813 only occurs for users with an empty home directory and if automated [homes] share is enabled in SAMBA. To determine which users have an empty home directory, the following command can be run: $ getent passwd | /usr/bin/grep '^[^:]*:[^:]*:[^:]*:[^:]*:[^:]*::' joe:x:62237:6883:Test User::/bin/ksh The above example shows that the user 'Test User' has an empty home directory. To determine if automated [homes] share is enabled in SAMBA, the following command can be run: $ /usr/bin/grep '\[homes\]' /etc/sfw/smb.conf || echo "Automated [homes] share was not enabled" 3. Symptoms Should the issue described in CVE-2009-2906 occur, the smbd(1M) daemon will consume a large amount of CPU resources. The prstat(1M) command may be used to verify the CPU usage of the smbd(1M) process as indicated in the following example: =========================Example output: =================================== PID USERNAME SIZE RSS STATE PRI NICE TIME CPU PROCESS/NLWP 28452 root 11M 1172K sleep 59 0 1:09:11 43% smbd/1 ... ============================================================================ On machines with multiple CPUs, the smbd(1M) daemon utilizes a large amount of resources on a single CPU. There are no predictable symptoms to indicate the issue described in CVE-2009-2813 is exploited to gain unauthorized access to the remote root filesystem. 4. Workaround To work around the issue described in CVE-2009-2813, the SAMBA service may be configured to disable the automated [homes] share. This may be done by removing the entry '[homes]' from '/etc/sfw/smb.conf' as follows: On Solaris 9: 1. Stop the SAMBA service: # /etc/init.d/samba stop 2. Edit the '/etc/sfw/smb.conf' file and remove the entry '[homes]' 3. Start the SAMBA service again: # /etc/init.d/samba start On Solaris 10: 1. Stop the SAMBA service: # svcadm disable samba 2. Edit the '/etc/sfw/smb.conf' file and remove the entry '[homes]' 3. Start the SAMBA service again: # svcadm enable samba To work around the issue described in CVE-2009-2906, disable the SAMBA service by using the following commands: On Solaris 9: # /etc/init.d/samba stop On Solaris 10: # svcadm disable samba 5. Resolution This issue is addressed in the following releases: SPARC Platform * Solaris 10 with patch 119757-17 or later * OpenSolaris based upon builds snv_127 or later x86 Platform * Solaris 10 with patch 119758-17 or later * OpenSolaris based upon builds snv_127 or later A final resolution is pending completion for Solaris 9. For more information on Security Sun Alerts, see Technical Instruction ID 213557. 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 2000-2009 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, CA 95054 U.S.A. All rights reserved ====================================================================== ========================================================= Les serveurs de référence du CERT-Renater http://www.urec.fr/securite http://www.cru.fr/securite http://www.renater.fr ========================================================= + CERT-RENATER | tel : 01-53-94-20-44 + + 151 bd de l'Hopital | fax : 01-53-94-20-41 + + 75013 Paris | email: certsvp@renater.fr + =========================================================