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FreeBSD-SA-03:11.sendmail                                   Security Advisory
                                                          The FreeBSD Project

Topic:          sendmail DNS map problem

Category:       contrib
Module:         contrib_sendmail
Announced:      2003-08-26
Credits:        Oleg Bulyzhin <oleg@rinet.ru>
Affects:        4.6-RELEASE (up to -p16), 4.7-RELEASE (up to -p13),
                4.8-RELEASE (up to -p3), 5.0-RELEASE (up to -p11)
                4-STABLE prior to Mar 29 19:33:18 2003 UTC
Corrected:      2003-08-25 22:33:14 UTC (RELENG_5_0)
                2003-08-25 22:35:23 UTC (RELENG_4_8)
                2003-08-25 22:36:10 UTC (RELENG_4_7)
                2003-08-25 22:38:53 UTC (RELENG_4_6)
FreeBSD only:   NO

For general information regarding FreeBSD Security Advisories,
including descriptions of the fields above, security branches, and the
following sections, please visit
<URL:http://www.freebsd.org/security/>.

I.   Background

FreeBSD includes sendmail(8), a general purpose internetwork mail
routing facility, as the default Mail Transfer Agent (MTA).

II.  Problem Description

Some versions of sendmail (8.12.0 through 8.12.8) contain a
programming error in the code that implements DNS maps.  A malformed
DNS reply packet may cause sendmail to call `free()' on an
uninitialized pointer.

NOTE: The default sendmail configuration in FreeBSD does not utilize
DNS maps.

III. Impact

Calling `free()' on an uninitialized pointer may result in a sendmail
child process crashing.  It may also be possible for an attacker to
somehow influence the value of the `uninitialized pointer' and cause
an arbitrary memory chunk to be freed.  This could further lead to
some other exploitable vulnerability, although no such cases are known
at this time.

IV.  Workaround

Do not use DNS maps.

V.   Solution

Do one of the following:

1) Upgrade your vulnerable system to 4-STABLE, 5.1-RELEASE, or to the
RELENG_5_1, RELENG_4_8, or RELENG_4_7 security branch dated after the
correction date (5.1-RELEASE-p2, 4.8-RELEASE-p4, or 4.7-RELEASE-p14,
respectively).

2) To patch your present system:

The following patch has been verified to apply to FreeBSD 5.0, 4.8,
4.7, and 4.6 systems.

a) Download the relevant patch from the location below, and verify the
detached PGP signature using your PGP utility.

ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-03:11/sendmail.patch
ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-03:11/sendmail.patch.asc

b) Execute the following commands as root:

# cd /usr/src
# patch < /path/to/patch
# cd /usr/src/lib/libsm
# make obj && make depend && make
# cd /usr/src/lib/libsmutil
# make obj && make depend && make
# cd /usr/src/usr.sbin/sendmail
# make obj && make depend && make && make install

c) Restart sendmail.  Execute the following command as root.

# /bin/sh /etc/rc.sendmail restart

VI.  Correction details

The following list contains the revision numbers of each file that was
corrected in FreeBSD.

Path                                                             Revision
  Branch
- -------------------------------------------------------------------------
src/UPDATING
  RELENG_5_0                                                   1.229.2.17
  RELENG_4_8                                                1.73.2.80.2.6
  RELENG_4_7                                               1.73.2.74.2.17
  RELENG_4_6                                               1.73.2.68.2.45
src/sys/conf/newvers.sh
  RELENG_5_0                                                    1.48.2.12
  RELENG_4_8                                                1.44.2.29.2.5
  RELENG_4_7                                               1.44.2.26.2.16
  RELENG_4_6                                               1.44.2.23.2.34
src/contrib/sendmail/src/sm_resolve.c
  RELENG_5_0                                                  1.1.1.4.2.1
  RELENG_4_8                                              1.1.1.1.2.2.4.1
  RELENG_4_7                                              1.1.1.1.2.2.2.1
  RELENG_4_6                                              1.1.1.1.2.1.2.2
- -------------------------------------------------------------------------

VII. References

<URL:http://www.sendmail.org/dnsmap1.html>
<URL:http://cve.mitre.org/cgi-bin/cvename.cgi?name=CAN-2003-0688>
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