-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 ============================================================================= FreeBSD-SA-11:02.bind Security Advisory The FreeBSD Project Topic: BIND remote DoS with large RRSIG RRsets and negative caching Category: contrib Module: bind Announced: 2011-05-28 Credits: Frank Kloeker, Michael Sinatra. Affects: All supported versions of FreeBSD. Corrected: 2011-05-28 00:58:19 UTC (RELENG_7, 7.4-STABLE) 2011-05-28 08:44:39 UTC (RELENG_7_3, 7.3-RELEASE-p6) 2011-05-28 08:44:39 UTC (RELENG_7_4, 7.4-RELEASE-p2) 2011-05-28 00:33:06 UTC (RELENG_8, 8.2-STABLE) 2011-05-28 08:44:39 UTC (RELENG_8_1, 8.1-RELEASE-p4) 2011-05-28 08:44:39 UTC (RELENG_8_2, 8.2-RELEASE-p2) CVE Name: CVE-2011-1910 For general information regarding FreeBSD Security Advisories, including descriptions of the fields above, security branches, and the following sections, please visit . I. Background BIND 9 is an implementation of the Domain Name System (DNS) protocols. The named(8) daemon is an Internet Domain Name Server. DNS Security Extensions (DNSSEC) provides data integrity, origin authentication and authenticated denial of existence to resolvers. II. Problem Description Very large RRSIG RRsets included in a negative response can trigger an assertion failure that will crash named(8) due to an off-by-one error in a buffer size check. III. Impact If named(8) is being used as a recursive resolver, an attacker who controls a DNS zone being resolved can cause named(8) to crash, resulting in a denial of (DNS resolving) service. DNSSEC does not need to be enabled on the resolver for it to be vulnerable. IV. Workaround No workaround is available, but systems not running the BIND DNS server or using it exclusively as an authoritative name server (i.e., not as a caching resolver) are not vulnerable. V. Solution Perform one of the following: 1) Upgrade your vulnerable system to 7-STABLE or 8-STABLE, or to the RELENG_8_2, RELENG_8_1, RELENG_7_4, or RELENG_7_3 security branch dated after the correction date. 2) To update your vulnerable system via a source code patch: The following patches have been verified to apply to FreeBSD 7.3, 7.4, 8.1 and 8.2 systems. a) Download the relevant patch from the location below, and verify the detached PGP signature using your PGP utility. # fetch http://security.FreeBSD.org/patches/SA-11:02/bind.patch # fetch http://security.FreeBSD.org/patches/SA-11:02/bind.patch.asc b) Execute the following commands as root: # cd /usr/src # patch < /path/to/patch # cd /usr/src/lib/bind # make obj && make depend && make && make install # cd /usr/src/usr.sbin/named # make obj && make depend && make && make install # /etc/rc.d/named restart 3) To update your vulnerable system via a binary patch: Systems running 7.3-RELEASE, 7.4-RELEASE, 8.1-RELEASE, or 8.2-RELEASE on the i386 or amd64 platforms can be updated via the freebsd-update(8) utility: # freebsd-update fetch # freebsd-update install VI. Correction details The following list contains the revision numbers of each file that was corrected in FreeBSD. CVS: Branch Revision Path - ------------------------------------------------------------------------- RELENG_7 src/contrib/bind9/lib/dns/ncache.c 1.1.1.2.2.3 RELENG_7_4 src/UPDATING 1.507.2.36.2.4 src/sys/conf/newvers.sh 1.72.2.18.2.7 src/contrib/bind9/lib/dns/ncache.c 1.1.1.2.2.2.2.1 RELENG_7_3 src/UPDATING 1.507.2.34.2.8 src/sys/conf/newvers.sh 1.72.2.16.2.10 src/contrib/bind9/lib/dns/ncache.c 1.1.1.2.10.1 RELENG_8 src/contrib/bind9/lib/dns/ncache.c 1.2.2.4 RELENG_8_2 src/UPDATING 1.632.2.19.2.4 src/sys/conf/newvers.sh 1.83.2.12.2.7 src/contrib/bind9/lib/dns/ncache.c 1.2.2.2.2.1 RELENG_8_1 src/UPDATING 1.632.2.14.2.7 src/sys/conf/newvers.sh 1.83.2.10.2.8 src/contrib/bind9/lib/dns/ncache.c 1.2.2.1.2.1 - ------------------------------------------------------------------------- Subversion: Branch/path Revision - ------------------------------------------------------------------------- stable/7/ r222399 releng/7.4/ r222416 releng/7.3/ r222416 stable/8/ r222396 releng/8.2/ r222416 releng/8.1/ r222416 head/ r222395 - ------------------------------------------------------------------------- VII. References http://www.isc.org/software/bind/advisories/cve-2011-1910 http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2011-1910 The latest revision of this advisory is available at http://security.FreeBSD.org/advisories/FreeBSD-SA-11:02.bind.asc -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.9 iEYEARECAAYFAk3gvuQACgkQFdaIBMps37L2iACgizZK4QS3rOaY0x7evMuyWIop OaoAn3Pku/9HCSUULC2xurSnGU3AtJcz =aG4/ -----END PGP SIGNATURE-----