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-----BEGIN PGP SIGNED MESSAGE----- =========================================================================== AUSCERT External Security Bulletin Redistribution ESB-2002.379 -- FreeBSD-SA-02:34.rpc Sun RPC XDR decoder contains buffer overflow 1 August 2002 =========================================================================== AusCERT Security Bulletin Summary --------------------------------- Product: Sun RPC Sun XDR Vendor: FreeBSD Operating System: All releases of FreeBSD up to and including 4.6.1-RELEASE-p3 BSD UNIX Linux Impact: Root Compromise Access Required: Remote Ref: AL-2002.09 - --------------------------BEGIN INCLUDED TEXT-------------------- - -----BEGIN PGP SIGNED MESSAGE----- ============================================================================= FreeBSD-SA-02:34.rpc Security Advisory The FreeBSD Project Topic: Sun RPC XDR decoder contains buffer overflow Category: core Module: libc Announced: 2002-07-31 Credits: ISS X-Force Affects: All releases of FreeBSD up to and including 4.6.1-RELEASE-p3 Corrected: 2002-07-31 14:45:29 UTC (RELENG_4) 2002-07-31 14:47:02 UTC (RELENG_4_6) 2002-07-31 14:49:18 UTC (RELENG_4_5) 2002-07-31 14:50:18 UTC (RELENG_4_4) FreeBSD only: NO I. Background Sun RPC is a remote procedure call framework which allows clients to invoke procedures in a server process over a network somewhat transparently. XDR is a mechanism for encoding data structures for use with RPC. NFS, NIS, and many other network services are built upon Sun RPC. The FreeBSD C runtime library (libc) contains an XDR encoder/decoder derived from Sun's RPC implementation. II. Problem Description An error in the calculation of memory needed for unpacking arrays in the XDR decoder can result in a heap buffer overflow. III. Impact Any application using Sun RPC may be vulnerable to the heap buffer overflow. Depending upon the application, this vulnerability may be exploitable and lead to arbitrary code execution. Though no exploits are known to exist currently, many RPC-based services run as the superuser (such as NFS, the NIS server, rpc.statd, and others) and thus this vulnerability should be considered high-risk. No RPC-based services are enabled by default in FreeBSD installations. IV. Workaround Do not run any RPC-based services. The RPC-based services running on a machine may be determined by: # rpcinfo -p <hostname> To disable any RPC-based services at next boot, add (or change if it is already present) the following lines in /etc/rc.conf: portmap_enable="NO" nfs_client_enable="NO" nfs_server_enable="NO" nis_client_enable="NO" nis_server_enable="NO" V. Solution Do one of the following: 1) Upgrade your vulnerable system to 4.6-STABLE; or to the RELENG_4_6, RELENG_4_5, or RELENG_4_4 security branch dated after the correction date (4.6.1-RELEASE-p4, 4.5-RELEASE-p12, or 4.4-RELEASE-p19). 2) To patch your present system: The following patch has been verified to apply to FreeBSD 4.4, 4.5, and 4.6 systems. a) Download the relevant patch from the location below, and verify the detached PGP signature using your PGP utility. # fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-02:34/rpc.patch # fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-02:34/rpc.patch.asc b) Execute the following commands as root: # cd /usr/src # patch < /path/to/patch c) Recompile the operating system as described in <URL:http://www.freebsd.org/doc/handbook/makeworld.html>. Note that any statically linked applications that are not part of the base system (i.e. from the Ports Collection or other 3rd-party sources) must be recompiled if they use Sun RPC. All affected applications must be restarted in order to use the corrected library. Though it is not required, rebooting may be the easiest way to accomplish this. VI. Correction details The following list contains the revision numbers of each file that was corrected in FreeBSD. Path Revision Branch - - ------------------------------------------------------------------------- src/lib/libc/xdr/xdr_array.c RELENG_4 1.8.2.2 RELENG_4_6 1.8.10.2 RELENG_4_5 1.8.8.2 RELENG_4_4 1.8.6.2 src/sys/conf/newvers.sh RELENG_4_6 1.44.2.23.2.9 RELENG_4_5 1.44.2.20.2.13 RELENG_4_4 1.44.2.17.2.18 - - ------------------------------------------------------------------------- VII. References <URL:http://online.securityfocus.com/archive/1/285308> <URL:http://bvlive01.iss.net/issEn/delivery/xforce/alertdetail.jsp?oid=20823> - -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.0.7 (FreeBSD) iQCVAwUBPUigCVUuHi5z0oilAQHdiAP8CcsDW7DufF7wYg0FcgoyQ2ugiBe21lgo YfAGfRcfxPtoZcmMApK3I5jUd/MRWCxBT3+ZcwtKe/aNH4hFlcpfcH5WYLVlrCgH 5QuVRR8dUfF/cWr8ejPq6xjXysUd/jMZWRQjAV8pCr+ngGSeMUeXQshB71ZyA5nk YrBUd7Uoenk= =lwhC - -----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 auscert@auscert.org.au and we will forward your request to the appropriate person. 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Previous advisories and external security bulletins can be retrieved from: http://www.auscert.org.au/Information/advisories.html If you believe that your system has been compromised, contact AusCERT or your representative in FIRST (Forum of Incident Response and Security Teams). Internet Email: auscert@auscert.org.au 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 emergencies. -----BEGIN PGP SIGNATURE----- Version: 2.6.3i Charset: noconv Comment: ftp://ftp.auscert.org.au/pub/auscert/AUSCERT_PGP.key iQCVAwUBPUlRfih9+71yA2DNAQGSZAP/Zgio7oHXD10A7koEaKz/RRUue2o5mXEC yFDV9Pb/uWLMJU6yvxyVNe+ORKVUl1GiX0IbPFX1eeZQpSKaHTmxWdUdKgfS139F EcCtOxrt+5gjYM7u5Bfh6LNW7D2BoG6aSCaA6fbNqWmSHxtuSI/GG3BLNuT0WrBc ZRq1ZnsTKb0= =ByFR -----END PGP SIGNATURE-----