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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
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