-----BEGIN PGP SIGNED MESSAGE----- ============================================================================= FreeBSD-SA-02:43.bind Security Advisory The FreeBSD Project Topic: multiple vulnerabilities in BIND [REVISED] Category: core Module: bind Announced: 2002-11-15 Credits: ISS X-Force Affects: All released versions of FreeBSD Corrected: 2002-11-14 05:15:15 UTC (RELENG_4) 2002-11-14 02:05:57 UTC (RELENG_4_7) 2002-11-14 03:18:41 UTC (RELENG_4_6) 2002-11-14 04:05:12 UTC (RELENG_4_5) 2002-11-14 05:11:57 UTC (RELENG_4_4) FreeBSD only: NO 0. Revision History v1.0 2002-11-14 Initial release. v1.1 2002-11-15 Correct patch instructions. Clarify workaround. Add CVE references. I. Background BIND 8 is an implementation of the Domain Name System (DNS) protocols. II. Problem Description ISS X-Force has disclosed several vulnerabilities affecting BIND 8. The names which ISS has given each vulnerability are used in this advisory. The first is a buffer overflow in the BIND 8 code responsible for creating DNS responses which include SIG resource records (RRs) from its internal cache (`BIND SIG Cached RR Overflow Vulnerability'). The second is an error in the BIND 8 code which constructs a response to an EDNS query (i.e. a query containing OPT RRs) with a large packet size. A miscalculation triggers an assertion failure (`BIND OPT DoS'). The third is a problem in the verification of SIG RR expiry times, which can result in a null pointer dereference (`BIND SIG Expiry Time DoS'). III. Impact BIND SIG Cached RR Overflow Vulnerability: A remote attacker may be able to cause a name server with recursion enabled to execute arbitrary code with the privileges of the name server process. BIND OPT DoS and BIND SIG Expiry Time DoS: A remote attacker may be able to cause the name server process to crash. IV. Workaround BIND 9 is not affected by these vulnerabilities. For those who have the option, upgrading to BIND 9 is recommended. BIND 9 is available in the FreeBSD Ports Collection (ports/net/bind9). The bind9 port includes migration notes in /usr/local/share/doc/bind9/misc/migration. Name servers with recursion disabled are not vulnerable to the `BIND SIG Cached RR Overflow Vulnerability' nor to the `BIND SIG Expiry Time DoS'. To disable recursion, edit the BIND 8 configuration file (default path /etc/namedb/named.conf) to add `recursion no;' and `fetch-glue no;' to the options statement. e.g., options { recursion no; fetch-glue no; /* ... other options ... */ }; Restart the name server after editing the configuration file. NOTE: This workaround is only appropriate for name servers which are authoritative only. Caching name servers will no longer function correctly if recursion is disabled. Restricting recursion to only your own organization's clients (by means of the `allow-recursion' directive) limits, but does not eliminate, the impact of these vulnerabilities by making them harder to exploit. Restricting recursion in this fashion is generally recommended. To restrict recursion, edit the BIND 8 configuration file to include an `allow-recursion' statement and an address list appropriate for your organization. e.g., options { allow-recursion { 10.0.0.0/8; }; /* ... other options ... */ }; Running BIND 8 as a non-privileged user (rather than as the superuser) may reduce the impact should the name server be compromised via the `BIND SIG Cached RR Overflow Vulnerability'. Running as a non-privileged user is generally recommended. Likewise, running BIND 8 in a chroot environment may reduce the impact and is generally recommended. V. Solution Do one of the following: 1) Upgrade your vulnerable system to 4.7-STABLE; or to the RELENG_4_7, RELENG_4_6, RELENG_4_5, or RELENG_4_4 security branch dated after the correction date (4.7-RELEASE-p2, 4.6.2-RELEASE-p5, 4.5-RELEASE-p23, 4.4-RELEASE-p30). 2) To patch your present system: The following patch has been verified to apply to FreeBSD 4.4, 4.5, 4.6, and 4.7 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-02:43/bind.patch # fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-02:43/bind.patch.asc b) Execute the following commands as root: # cd /usr/src # patch < /path/to/patch # cd /usr/src/lib/libbind # make depend && make # cd /usr/src/lib/libisc # make depend && make # cd /usr/src/usr.sbin/named # make depend && make && make install # cd /usr/src/libexec/named-xfer # make depend && make && make install After upgrading or patching your system, you must restart named. Execute the following command as root: # ndc restart VI. Correction details Path Revision Branch - ------------------------------------------------------------------------- src/contrib/bind/CHANGES RELENG_4 1.1.1.7.2.8 RELENG_4_7 1.1.1.7.2.7.2.1 RELENG_4_6 1.1.1.7.2.6.2.2 RELENG_4_5 1.1.1.7.2.4.4.2 RELENG_4_4 1.1.1.7.2.4.2.2 src/contrib/bind/bin/named/db_defs.h RELENG_4 1.1.1.2.2.6 RELENG_4_7 1.1.1.2.2.5.2.1 RELENG_4_6 1.1.1.2.2.4.2.2 RELENG_4_5 1.1.1.2.2.3.4.2 RELENG_4_4 1.1.1.2.2.3.2.2 src/contrib/bind/bin/named/db_sec.c RELENG_4 1.1.1.1.4.4 RELENG_4_7 1.1.1.1.4.3.4.1 RELENG_4_6 1.1.1.1.4.3.2.1 RELENG_4_5 1.1.1.1.4.2.6.2 RELENG_4_4 1.1.1.1.4.2.4.2 src/contrib/bind/bin/named/ns_defs.h RELENG_4 1.1.1.3.2.7 RELENG_4_7 1.1.1.3.2.6.2.1 RELENG_4_6 1.1.1.3.2.5.2.2 RELENG_4_5 1.1.1.3.2.3.4.2 RELENG_4_4 1.1.1.3.2.3.2.2 src/contrib/bind/bin/named/ns_ncache.c RELENG_4 1.1.1.2.2.3 RELENG_4_7 1.1.1.2.2.2.4.1 RELENG_4_6 1.1.1.2.2.2.2.1 RELENG_4_5 1.1.1.2.2.1.6.2 RELENG_4_4 1.1.1.2.2.1.4.2 src/contrib/bind/bin/named/ns_req.c RELENG_4 1.1.1.2.2.11 RELENG_4_7 1.1.1.2.2.10.2.1 RELENG_4_6 1.1.1.2.2.9.2.2 RELENG_4_5 1.1.1.2.2.7.4.2 RELENG_4_4 1.1.1.2.2.7.2.2 src/contrib/bind/bin/named/ns_resp.c RELENG_4 1.1.1.2.2.8 RELENG_4_7 1.1.1.2.2.7.2.1 RELENG_4_6 1.1.1.2.2.6.2.2 RELENG_4_5 1.1.1.2.2.4.4.2 RELENG_4_4 1.1.1.2.2.4.2.2 src/contrib/bind/lib/nameser/ns_name.c RELENG_4 1.1.1.2.2.4 RELENG_4_7 1.1.1.2.2.3.2.1 RELENG_4_6 1.1.1.2.2.2.2.2 RELENG_4_5 1.1.1.2.2.1.6.2 RELENG_4_4 1.1.1.2.2.1.4.2 src/contrib/bind/lib/nameser/ns_samedomain.c RELENG_4 1.1.1.1.4.1 RELENG_4_7 1.1.1.1.14.1 RELENG_4_6 1.1.1.1.12.1 RELENG_4_5 1.1.1.1.10.1 RELENG_4_4 1.1.1.1.8.1 src/sys/conf/newvers.sh RELENG_4_7 1.44.2.26.2.4 RELENG_4_6 1.44.2.23.2.22 RELENG_4_5 1.44.2.20.2.24 RELENG_4_4 1.44.2.17.2.29 - ------------------------------------------------------------------------- VII. 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