__________________________________________________________ The U.S. Department of Energy Computer Incident Advisory Capability ___ __ __ _ ___ / | /_\ / \___ __|__ / \ \___ __________________________________________________________ INFORMATION BULLETIN Samba Format String Bug February 7, 2007 19:00 GMT Number R-122 ______________________________________________________________________________ PROBLEM: There is a format string bug in afsacl.so VGS plugin in Samba. PLATFORM: Samba 3.0.23d Debian GNU/Linux 3.1 (sarge) DAMAGE: May lead to the execution of arbitrary code. SOLUTION: Upgrade to the appropriate version. ______________________________________________________________________________ VULNERABILITY The risk is MEDIUM. A user with local access to a directory ASSESSMENT: managed with the afsacl.so library (windows to AFS mapping) can execute arbitrary code. ______________________________________________________________________________ LINKS: CIAC BULLETIN: http://www.ciac.org/ciac/bulletins/r-122.shtml ORIGINAL BULLETIN: http://samba.org/samba/security/CVE-2007-0454.html ADDITIONAL LINK: Debian Security Advisory DSA-1257-1 http://www.devian.org/security/2007/dsa-1257 CVE: http://www.cve.mitre.org/cgi-bin/cvename.cgi?name= CVE-2007-0454 ______________________________________________________________________________ [****** Samba Bulletin Starts ******] CVE-2007-0454: Format string bug in afsacl.so VFS plugin ========================================================== == == Subject: Format string bug in afsacl.so VFS plugin. == CVE ID#: CVE-2007-0454 == == Versions: The AFS ACL mapping VFS plugin distributed == in Samba 3.0.6 - 3.0.23d (inclusive) == == Summary: The name of a file on the server's share == is used as the format string when setting == an NT security descriptor through the == afsacl.so VFS plugin. == ========================================================== =========== Description =========== NOTE: This security advisory only impacts Samba servers that share AFS file systems to CIFS clients and which have been explicitly instructed in smb.conf to load the afsacl.so VFS module. The source defect results in the name of a file stored on disk being used as the format string in a call to snprintf(). This bug becomes exploitable only when a user is able to write to a share which utilizes Samba's afsacl.so library for setting Windows NT access control lists on files residing on an AFS file system. ================== Patch Availability ================== A patch against Samba 3.0.23d has been attached to this email. This fix has be incorporated into the Samba 3.0.24 release. Patches are also available from at the Samba Security page (http://www.samba.org/samba/security). ========== Workaround ========== An unpatched server may be protected by removing all references to the afsacl.so VFS module from shares in smb.conf. ======= Credits ======= This vulnerability was reported (including a proposed patch) to Samba developers by . Much thanks to zybadawg333 for the cooperation and patience in the announcement of this defect. The time line is as follows: * Jan 8, 2007: Defect first reported to the security@samba.org email alias. * Jan 8, 2007: Initial developer response by Jeremy Allison confirming the issue. * Jan 29, 2007: Announcement to vendor-sec mailing list * Feb 5, 2007: Public issue of security advisory. ========================================================== == Our Code, Our Bugs, Our Responsibility. == The Samba Team ========================================================== [****** Samba Bulletin ENDS ******] _______________________________________________________________________________ CIAC wishes to acknowledge the contributions of Samba for the information contained in this bulletin. _______________________________________________________________________________ CIAC, the Computer Incident Advisory Capability, is the computer security incident response team for the U.S. Department of Energy (DOE) and the emergency backup response team for the National Institutes of Health (NIH). CIAC is located at the Lawrence Livermore National Laboratory in Livermore, California. CIAC is also a founding member of FIRST, the Forum of Incident Response and Security Teams, a global organization established to foster cooperation and coordination among computer security teams worldwide. CIAC services are available to DOE, DOE contractors, and the NIH. CIAC can be contacted at: Voice: +1 925-422-8193 (7x24) FAX: +1 925-423-8002 STU-III: +1 925-423-2604 E-mail: ciac@ciac.org Previous CIAC notices, anti-virus software, and other information are available from the CIAC Computer Security Archive. World Wide Web: http://www.ciac.org/ Anonymous FTP: ftp.ciac.org PLEASE NOTE: Many users outside of the DOE, ESnet, and NIH computing communities receive CIAC bulletins. If you are not part of these communities, please contact your agency's response team to report incidents. Your agency's team will coordinate with CIAC. The Forum of Incident Response and Security Teams (FIRST) is a world-wide organization. A list of FIRST member organizations and their constituencies can be obtained via WWW at http://www.first.org/. This document was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor the University of California nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial products, process, or service by trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation or favoring by the United States Government or the University of California. 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