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-----BEGIN PGP SIGNED MESSAGE----- =========================================================================== AUSCERT External Security Bulletin Redistribution ESB-2002.662 -- CERT Advisory CA-2002-34 Buffer Overflow in Solaris X Window Font Service 26 November 2002 =========================================================================== AusCERT Security Bulletin Summary --------------------------------- Product: XFS (X Window Font Service) Daemon Vendor: Sun Microsystems Operating System: Solaris 2.5.1 Solaris 2.6 Solaris 7 Solaris 8 Solaris 9 Platform: SPARC Intel Impact: Execute Arbitrary Code/Commands Denial of Service Access Required: Remote - --------------------------BEGIN INCLUDED TEXT-------------------- - -----BEGIN PGP SIGNED MESSAGE----- CERT Advisory CA-2002-34 Buffer Overflow in Solaris X Window Font Service Original release date: November 25, 2002 Last revised: -- Source: CERT/CC A complete revision history can be found at the end of this file. Systems Affected * Sun Microsystems Solaris 2.5.1 (Sparc/Intel) * Sun Microsystems Solaris 2.6 (Sparc/Intel) * Sun Microsystems Solaris 7 (Sparc/Intel) * Sun Microsystems Solaris 8 (Sparc/Intel) * Sun Microsystems Solaris 9 (Sparc) Overview The Solaris X Window Font Service (XFS) daemon (fs.auto) contains a remotely exploitable buffer overflow vulnerability that could allow an attacker to execute arbitrary code or cause a denial of service. I. Description A remotely exploitable buffer overflow vulnerability exists in the Solaris X Window Font Service (XFS) daemon (fs.auto). Exploitation of this vulnerability can lead to arbitrary code execution on a vulnerable Solaris system. This vulnerability was discovered by ISS X-Force. The Solaris X Window Font Service (XFS) serves font files to clients. Sun describes the XFS service as follows: The X Font Server is a simple TCP/IP-based service that serves font files to its clients. Clients connect to the server to request a font set, and the server reads the font files off the disk and serves them to the clients. The X Font Server daemon consists of a server binary /usr/openwin/bin/xfs. The XFS daemon is installed and running by default on all versions of the Solaris operating system. Further information about this vulnerability may be found in VU#312313. http://www.kb.cert.org/vuls/id/312313 This vulnerability is also being referred to as CAN-2002-1317 by CVE. Note this vulnerability is in the X Window Font Server, and not the filesystem of a similar name. II. Impact A remote attacker can execute arbitrary code with the privileges of the fs.auto daemon (typically nobody) or cause a denial of service by crashing the service. III. Solution Apply a patch from your vendor Appendix A contains information provided by vendors for this advisory. As vendors report new information to the CERT/CC, we will update this section and note the changes in our revision history. If a particular vendor is not listed below, we have not received their comments. Please contact your vendor directly. Disable vulnerable service Until patches can be applied, you may wish to disable the XFS daemon (fs.auto). As a best practice, the CERT/CC recommends disabling all services that are not explicitly required. On a typical Solaris system, it should be possible to disable the fs.auto daemon by commenting out the relevant entries in /etc/inetd.conf and then restarting the inetd process. Workarounds Block access to port 7100/TCP at your network perimeter. Note that this will not protect vulnerable hosts within your network perimeter. Appendix A. - Vendor Information NetBSD NetBSD ships the xfs from XFree86, though its not on or used by default. OpenBSD We do not have XFS. SGI We're not vulnerable to this. Sun Microsystems The Solaris X font server (xfs(1)) is affected by VU#312313 in the following supported versions of Solaris: Solaris 2.6 Solaris 7 Solaris 8 Solaris 9 Patches are being generated for all of the above releases. Sun will be publishing a Sun Alert for this issue at the following location shortly: http://sunsolve.Sun.COM/pub-cgi/retrieve.pl?doc=fsalert/48879 The patches will be available from: http://sunsolve.sun.com/securitypatch Appendix B. - References 1. ISS X-Force Security Advisory: Solaris fs.auto Remote Compromise Vulnerability - http://bvlive01.iss.net/issEn/delivery/xforce/alertdetail.jsp?oid= 21541 2. Sun Cluster 3.0 U1 Data Services Developer's Guide, Chapter 6: Sample DSDL Resource Type Implementation - http://docs.sun.com/db/doc/806-7072/6jfvjtg1l?q=xfs&a=view 3. CERT/CC Vulnerability Note: VU#312313 - http://www.kb.cert.org/vuls/id/312313 4. CVE reference number CAN-2002-1317. Information available at http://cve.mitre.org _________________________________________________________________ Internet Security Systems publicly reported this vulnerability. _________________________________________________________________ Authors: Ian A. Finlay and Shawn V. Hernan. ______________________________________________________________________ This document is available from: http://www.cert.org/advisories/CA-2002-34.html ______________________________________________________________________ CERT/CC Contact Information Email: email@example.com Phone: +1 412-268-7090 (24-hour hotline) Fax: +1 412-268-6989 Postal address: CERT Coordination Center Software Engineering Institute Carnegie Mellon University Pittsburgh PA 15213-3890 U.S.A. CERT/CC personnel answer the hotline 08:00-17:00 EST(GMT-5) / EDT(GMT-4) Monday through Friday; they are on call for emergencies during other hours, on U.S. holidays, and on weekends. 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Revision History November 25, 2002: Initial release - -----BEGIN PGP SIGNATURE----- Version: PGP 6.5.8 iQCVAwUBPeK49WjtSoHZUTs5AQHV5wP7BzZtllAnLIcz88VnsMZmC8PB8X1stQDx aNnrPLhgQ7SWXZM/ESAsBBU+ieQodPJlmxy3yb00812uJmaO9wJPMoRnJnrZPkvU 6iSVJpo3nP85sS+mzpneavM7EuFr7BvJ0+jqhl/21GgMCaJz8zul0rVjUWDOBHl1 NNaWQi2Urb8= =L7NC - -----END PGP SIGNATURE----- - --------------------------END INCLUDED TEXT-------------------- You have received this e-mail bulletin as a result of your organisation's registration with AusCERT. The mailing list you are subscribed to is maintained within your organisation, so if you do not wish to continue receiving these bulletins you should contact your local IT manager. If you do not know who that is, please send an email to email@example.com and we will forward your request to the appropriate person. This security bulletin is provided as a service to AusCERT's members. As AusCERT did not write the document quoted above, AusCERT has had no control over its content. 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Internet Email: firstname.lastname@example.org Facsimile: (07) 3365 7031 Telephone: (07) 3365 4417 (International: +61 7 3365 4417) AusCERT personnel answer during Queensland business hours which are GMT+10:00 (AEST). On call after hours for member emergencies only. -----BEGIN PGP SIGNATURE----- Version: 2.6.3i Charset: noconv Comment: http://www.auscert.org.au/render.html?it=1967 iQCVAwUBPeNQDih9+71yA2DNAQECOQP/QwuB6dQqBFsOaAVWTHnUTOAJznzR76iP +/CHVh2urXjJRdMJlAi8t0dgYQ+mzGRZuWy8pXofnmKyVNkjIzp0AJ2RmsFZcEGj crth3ax389cCYDeWF51Dq1qEfohFc+q47z15kt2Sf+pxuZBD7tBonvsX/0g6URZc PtkZDq3ituk= =t9Oe -----END PGP SIGNATURE-----