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-----BEGIN PGP SIGNED MESSAGE----- =========================================================================== AUSCERT External Security Bulletin Redistribution ESB-2002.309 -- FreeBSD-SA-02:28.resolv buffer overflow in resolver 27 June 2002 =========================================================================== AusCERT Security Bulletin Summary --------------------------------- Product: dns resolver Vendor: FreeBSD Operating System: FreeBSD 4.6 and prior Impact: Execute Arbitrary Code/Commands Access Required: Remote - --------------------------BEGIN INCLUDED TEXT-------------------- - -----BEGIN PGP SIGNED MESSAGE----- ============================================================================= FreeBSD-SA-02:28.resolv Security Advisory The FreeBSD Project Topic: buffer overflow in resolver Category: core Module: libc Announced: 2002-06-26 Credits: Joost Pol <joost@pine.nl> Affects: All releases prior to and including 4.6-RELEASE Corrected: 2002-06-26 06:34:18 UTC (RELENG_4) 2002-06-26 08:44:24 UTC (RELENG_4_6) 2002-06-26 18:53:20 UTC (RELENG_4_5) FreeBSD only: NO I. Background The resolver implements functions for making, sending and interpreting query and reply messages with Internet domain name servers. Hostnames, IP addresses, and other information are queried using the resolver. II. Problem Description DNS messages have specific byte alignment requirements, resulting in padding in messages. In a few instances in the resolver code, this padding is not taken into account when computing available buffer space. As a result, the parsing of a DNS message may result in a buffer overrun of up to a few bytes for each record included in the message. III. Impact An attacker (either a malicious domain name server or an agent that can spoof DNS messages) may produce a specially crafted DNS message that will exploit this bug when parsed by an application using the resolver. It may be possible for such an exploit to result in the execution of arbitrary code with the privileges of the resolver-using application. Though no exploits are known to exist today, since practically all Internet applications utilize the resolver, the severity of this issue is high. IV. Workaround There is currently no workaround. V. Solution Do one of the following: 1) Upgrade your vulnerable system to 4.6-STABLE; or to the RELENG_4_6 or RELENG_4_5 security branch dated after the correction date (4.6-RELEASE-p1 or 4.5-RELEASE-p7). 2) To patch your present system: The following patch has been verified to apply to FreeBSD 4.5 and FreeBSD 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-02:28/resolv.patch # fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-02:28/resolv.patch.asc b) Execute the following commands as root: # cd /usr/src # patch < /path/to/patch c) Recompile the operating systems 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. VI. Correction details The following list contains the revision numbers of each file that was corrected in FreeBSD. Path Revision Branch - - ------------------------------------------------------------------------- src/lib/libc/net/gethostbydns.c RELENG_4 1.27.2.2 RELENG_4_6 1.27.10.1 RELENG_4_5 1.27.8.1 src/lib/libc/net/getnetbydns.c RELENG_4 1.13.2.2 RELENG_4_6 1.13.2.1.8.1 RELENG_4_5 1.13.2.1.6.1 src/lib/libc/net/name6.c RELENG_4 1.6.2.6 RELENG_4_6 1.6.2.5.8.1 RELENG_4_5 1.6.2.5.6.1 src/sys/conf/newvers.sh RELENG_4_6 1.44.2.23.2.2 RELENG_4_5 1.44.2.20.2.8 - - ------------------------------------------------------------------------- VII. References <URL:http://www.pine.nl/advisories/pine-cert-20020601.html> - -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.0.7 (FreeBSD) iQCVAwUBPRoQOVUuHi5z0oilAQG3cAP/d7Gb2rdkSjZKCR0NI+QzMibgySVTXOtF sdoJrYka/XnIpFMVAyXl36bibtRKbwfCyv/rEX39YSas7tqReizwAABoaRF956Qb qlek1ONvvd+Tj6+WpEEueX/VdPqGQuqMk0BoguIbOgwAya6ZFYJ9ZKAHHSN9YqO8 ZGTC8pmqfGI= =s76v - -----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. This security bulletin is provided as a service to AusCERT's members. 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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 member emergencies. -----BEGIN PGP SIGNATURE----- Version: 2.6.3i Charset: noconv Comment: ftp://ftp.auscert.org.au/pub/auscert/AUSCERT_PGP.key iQCVAwUBPRs2TCh9+71yA2DNAQGT9AP9FcwCMaE/j+kEHQZQT+ktb5X/meHDsMUi 1gvuCViSUOXLtlny43HR0amPxWXTXa/M/VTghq90ZjCs7lxGALkP5jJyrCOLQ8lh VpRktLsoKUrrl0i3d/PYuPuzWFSxd5IRPWJr2JDlB3cjPlPz2WAbjjSct+6Xku2L D4OArH7irZM= =oUSs -----END PGP SIGNATURE-----