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 From:  Manuel Kasper <mk at neon1 dot net>
 To:  m0n0wall dash dev at lists dot m0n0 dot ch
 Subject:  FreeBSD Security Advisory FreeBSD-SA-06:11.ipsec (fwd)
 Date:  Wed, 22 Mar 2006 17:38:17 +0100
The next m0n0wall release (1.22) will have a FreeBSD 4.11-RELEASE-p16
kernel then...

- Manuel

------------ Forwarded Message ------------

From: FreeBSD Security Advisories <security dash advisories at freebsd dot org>
To: FreeBSD Security Advisories <security dash advisories at freebsd dot org>
Subject: FreeBSD Security Advisory FreeBSD-SA-06:11.ipsec

Hash: SHA1

======== FreeBSD-SA-06:11.ipsec
Security Advisory
The FreeBSD Project

Topic:          IPsec replay attack vulnerability

Category:       core
Module:         sys_netipsec
Announced:      2006-03-22
Credits:        Pawel Jakub Dawidek
Affects:        All FreeBSD releases since 4.8-RELEASE
Corrected:      2006-03-22 16:01:08 UTC (RELENG_6, 6.1-STABLE)
                2006-03-22 16:01:38 UTC (RELENG_6_0, 6.0-RELEASE-p6)
                2006-03-22 16:01:56 UTC (RELENG_5, 5.5-STABLE)
                2006-03-22 16:02:17 UTC (RELENG_5_4, 5.4-RELEASE-p13)
                2006-03-22 16:02:35 UTC (RELENG_5_3, 5.3-RELEASE-p28)
                2006-03-22 16:02:49 UTC (RELENG_4, 4.11-STABLE)
                2006-03-22 16:03:05 UTC (RELENG_4_11,
4.11-RELEASE-p16)                 2006-03-22 16:03:25 UTC
(RELENG_4_10, 4.10-RELEASE-p22) CVE Name:       CVE-2006-0905

For general information regarding FreeBSD Security Advisories,
including descriptions of the fields above, security branches, and the
following sections, please visit

I.   Background

IPsec is a set of protocols, including ESP (Encapsulating Security
Payload) and AH (Authentication Header), that provide security
services for IP datagrams.  ESP protects IP payloads from
wire-tapping by encrypting them using secret key cryptography
algorithms.  AH guarantees the integrity of IP packets and protects
them from intermediate alteration or impersonation by attaching a
cryptographic checksum computed using one-way hash functions.

II.  Problem Description

IPsec provides an anti-replay service which when enabled prevents an
attacker from successfully executing a replay attack.  This is done
through the verification of sequence numbers.  A programming error in
the fast_ipsec(4) implementation results in the sequence number
associated with a Security Association not being updated, allowing
packets to unconditionally pass sequence number verification checks.

III. Impact

An attacker able to to intercept IPSec packets can replay them.  If
higher level protocols which do not provide any protection against
packet replays (e.g., UDP) are used, this may have a variety of

IV.  Workaround

No workaround is available.

V.   Solution

Perform one of the following:

1) Upgrade your vulnerable system to 4-STABLE, 5-STABLE, or 6-STABLE,
or to the RELENG_6_0, RELENG_5_4, RELENG_5_3, RELENG_4_11, or
RELENG_4_10 security branch dated after the correction date.

2) To patch your present system:

The following patches have been verified to apply to FreeBSD 4.10,
4.11, 5.3, 5.4, and 6.0 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-06:11/ipsec.patch
# fetch
# ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-06:11/ipsec.patch
# .asc

b) Apply the patch.

# cd /usr/src
# patch < /path/to/patch

c) Recompile your kernel as described in
<URL:http://www.freebsd.org/handbook/kernelconfig.html> and reboot the

VI.  Correction details

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

Revision   Path
---- RELENG_4
  src/sys/netipsec/xform_esp.c RELENG_4_11
  src/UPDATING   src/sys/conf/newvers.sh   src/sys/netipsec/xform_esp.c RELENG_4_10
  src/UPDATING   src/sys/conf/newvers.sh   src/sys/netipsec/xform_esp.c RELENG_5
  src/sys/netipsec/xform_esp.c RELENG_5_4
1.342.   src/sys/conf/newvers.sh   src/sys/netipsec/xform_esp.c RELENG_5_3
1.342.   src/sys/conf/newvers.sh   src/sys/netipsec/xform_esp.c RELENG_6
  src/sys/netipsec/xform_esp.c RELENG_6_0
1.416.   src/sys/conf/newvers.sh   src/sys/netipsec/xform_esp.c -

VII. References


The latest revision of this advisory is available at
sec.asc -----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.2.2 (FreeBSD)

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