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Posted on 01 August 2007
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FreeBSD-SA-07:07.bind Security Advisory
The FreeBSD Project
Topic: Predictable query ids in named(8)
Category: contrib
Module: bind
Announced: 2007-08-01
Credits: Amit Klein
Affects: FreeBSD 5.3 and later.
Corrected: 2007-07-25 08:23:08 UTC (RELENG_6, 6.2-STABLE)
2007-08-01 20:44:58 UTC (RELENG_6_2, 6.2-RELEASE-p7)
2007-08-01 20:45:49 UTC (RELENG_6_1, 6.1-RELEASE-p19)
2007-07-25 08:24:40 UTC (RELENG_5, 5.5-STABLE)
2007-08-01 20:48:19 UTC (RELENG_5_5, 5.5-RELEASE-p15)
CVE Name: CVE-2007-2926
For general information regarding FreeBSD Security Advisories,
including descriptions of the fields above, security branches, and the
following sections, please visit <URL:http://security.FreeBSD.org/>.
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 requests
contain a query id which is used match a DNS request with the response
and to make it harder for anybody but the DNS server which received the
request to send a valid response.
II. Problem Description
When named(8) is operating as a recursive DNS server or sending NOTIFY
requests to slave DNS servers, named(8) uses a predictable query id.
III. Impact
An attacker who can see the query id for some request(s) sent by named(8)
is likely to be able to perform DNS cache poisoning by predicting the
query id for other request(s).
IV. Workaround
No workaround is available.
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.
# fetch http://security.FreeBSD.org/patches/SA-07:07/bind.patch
# fetch http://security.FreeBSD.org/patches/SA-07:07/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
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/bin/named/client.c 1.1.1.1.2.5
src/contrib/bind9/lib/dns/dispatch.c 1.1.1.1.2.3
src/contrib/bind9/lib/dns/include/dns/dispatch.h 1.1.1.1.2.2
RELENG_5_5
src/UPDATING 1.342.2.35.2.15
src/sys/conf/newvers.sh 1.62.2.21.2.17
src/contrib/bind9/bin/named/client.c 1.1.1.1.2.3.2.1
src/contrib/bind9/lib/dns/dispatch.c 1.1.1.1.2.1.6.1
src/contrib/bind9/lib/dns/include/dns/dispatch.h 1.1.1.1.2.1.6.1
RELENG_6
src/contrib/bind9/bin/named/client.c 1.1.1.2.2.3
src/contrib/bind9/lib/dns/dispatch.c 1.1.1.1.4.2
src/contrib/bind9/lib/dns/include/dns/dispatch.h 1.1.1.1.4.1
RELENG_6_2
src/UPDATING 1.416.2.29.2.10
src/sys/conf/newvers.sh 1.69.2.13.2.10
src/contrib/bind9/bin/named/client.c 1.1.1.2.2.1.4.2
src/contrib/bind9/lib/dns/dispatch.c 1.1.1.1.10.2
src/contrib/bind9/lib/dns/include/dns/dispatch.h 1.1.1.1.10.1
RELENG_6_1
src/UPDATING 1.416.2.22.2.21
src/sys/conf/newvers.sh 1.69.2.11.2.21
src/contrib/bind9/bin/named/client.c 1.1.1.2.2.1.2.1
src/contrib/bind9/lib/dns/dispatch.c 1.1.1.1.8.1
src/contrib/bind9/lib/dns/include/dns/dispatch.h 1.1.1.1.8.1
- -------------------------------------------------------------------------
VII. References
http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2007-2926
http://www.isc.org/sw/bind/bind-security.php
http://www.trusteer.com/docs/bind9dns_s.html
The latest revision of this advisory is available at
http://security.FreeBSD.org/advisories/FreeBSD-SA-07:07.bind.asc
