-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 ============================================================================= FreeBSD-SA-07:02.bind Security Advisory The FreeBSD Project Topic: Multiple Denial of Service vulnerabilities in named(8) Category: contrib Module: bind Announced: 2007-02-09 Affects: FreeBSD 5.3 and later. Corrected: 2007-02-07 00:42:09 UTC (RELENG_6, 6.2-STABLE) 2007-02-09 20:24:15 UTC (RELENG_6_2, 6.2-RELEASE-p1) 2007-02-09 20:23:29 UTC (RELENG_6_1, 6.1-RELEASE-p13) 2007-02-07 00:46:35 UTC (RELENG_5, 5.5-STABLE) 2007-02-09 20:22:44 UTC (RELENG_5_5, 5.5-RELEASE-p11) CVE Name: CVE-2007-0493, CVE-2007-0494 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) are additional protocol options that add authentication and integrity to the DNS protocols. II. Problem Description A type * (ANY) query response containing multiple RRsets can trigger an assertion failure. Certain recursive queries can cause the nameserver to crash by using memory which has already been freed. III. Impact A remote attacker sending a type * (ANY) query to an authoritative DNS server for a DNSSEC signed zone can cause the named(8) daemon to exit, resulting in a Denial of Service. A remote attacker sending recursive queries can cause the nameserver to crash, resulting in a Denial of Service. IV. Workaround There is no workaround available, but systems which are not authoritative servers for DNSSEC signed zones are not affected by the first issue; and systems which do not permit untrusted users to perform recursive DNS resolution are not affected by the second issue. Note that the default configuration for named(8) in FreeBSD allows local access only (which on many systems is equivalent to refusing access to untrusted users). V. Solution Perform one of the following: 1) Upgrade your vulnerable system to 5-STABLE, or 6-STABLE, or to the RELENG_6_2, RELENG_6_1, or RELENG_5_5 security branch dated after the correction date. 2) To patch your present system: The following patches have been verified to apply to FreeBSD 5.5, 6.1, and 6.2 systems. a) Download the relevant patch from the location below, and verify the detached PGP signature using your PGP utility. [FreeBSD 5.5, FreeBSD 6.1] # fetch http://security.FreeBSD.org/patches/SA-07:02/bind61.patch # fetch http://security.FreeBSD.org/patches/SA-07:02/bind61.patch.asc [FreeBSD 6.2] # fetch http://security.FreeBSD.org/patches/SA-07:02/bind62.patch # fetch http://security.FreeBSD.org/patches/SA-07:02/bind62.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 c) Restart the named application: # /etc/rc.d/named restart VI. Correction details The following list contains the revision numbers of each file that was corrected in FreeBSD. Branch Revision Path - ------------------------------------------------------------------------- RELENG_5 src/contrib/bind9/lib/dns/resolver.c 1.1.1.1.2.8 src/contrib/bind9/lib/dns/validator.c 1.1.1.1.2.5 src/contrib/bind9/lib/dns/include/dns/validator.h 1.1.1.1.2.4 RELENG_5_5 src/UPDATING 1.342.2.35.2.11 src/sys/conf/newvers.sh 1.62.2.21.2.13 src/contrib/bind9/lib/dns/resolver.c 1.1.1.1.2.4.2.2 src/contrib/bind9/lib/dns/validator.c 1.1.1.1.2.3.2.1 src/contrib/bind9/lib/dns/include/dns/validator.h 1.1.1.1.2.2.2.1 RELENG_6 src/contrib/bind9/lib/dns/resolver.c 1.1.1.2.2.6 src/contrib/bind9/lib/dns/validator.c 1.1.1.2.2.3 src/contrib/bind9/lib/dns/include/dns/validator.h 1.1.1.1.4.3 RELENG_6_2 src/UPDATING 1.416.2.29.2.4 src/sys/conf/newvers.sh 1.69.2.13.2.4 src/contrib/bind9/lib/dns/resolver.c 1.1.1.2.2.4.2.2 src/contrib/bind9/lib/dns/validator.c 1.1.1.2.2.1.4.2 src/contrib/bind9/lib/dns/include/dns/validator.h 1.1.1.1.4.1.4.2 RELENG_6_1 src/UPDATING 1.416.2.22.2.15 src/sys/conf/newvers.sh 1.69.2.11.2.15 src/contrib/bind9/lib/dns/resolver.c 1.1.1.2.2.2.2.2 src/contrib/bind9/lib/dns/validator.c 1.1.1.2.2.1.2.1 src/contrib/bind9/lib/dns/include/dns/validator.h 1.1.1.1.4.1.2.1 - ------------------------------------------------------------------------- VII. References http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2007-0493 http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2007-0494 The latest revision of this advisory is available at http://security.FreeBSD.org/advisories/FreeBSD-SA-07:02.bind.asc -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.6 (FreeBSD) iD8DBQFFzNnpFdaIBMps37IRAsCVAJ9qvyFe04YWnkvYkFQPsSTIP+SLYgCfUhO8 alXiQEsy1iSwSI66d/e7gSk= =HmF6 -----END PGP SIGNATURE-----