147 lines
6 KiB
Text
147 lines
6 KiB
Text
-----BEGIN PGP SIGNED MESSAGE-----
|
|
Hash: SHA512
|
|
|
|
=============================================================================
|
|
FreeBSD-SA-14:19.tcp Security Advisory
|
|
The FreeBSD Project
|
|
|
|
Topic: Denial of Service in TCP packet processing
|
|
|
|
Category: core
|
|
Module: inet
|
|
Announced: 2014-09-16
|
|
Credits: Jonathan Looney (Juniper SIRT)
|
|
Affects: All supported versions of FreeBSD.
|
|
Corrected: 2014-09-16 09:48:35UTC (stable/10, 10.1-PRERELEASE)
|
|
2014-09-16 09:48:35 UTC (stable/10, 10.1-BETA1-p1)
|
|
2014-09-16 09:50:19 UTC (releng/10.0, 10.0-RELEASE-p9)
|
|
2014-09-16 09:49:11 UTC (stable/9, 9.3-STABLE)
|
|
2014-09-16 09:50:19 UTC (releng/9.3, 9.3-RELEASE-p2)
|
|
2014-09-16 09:50:19 UTC (releng/9.2, 9.2-RELEASE-p12)
|
|
2014-09-16 09:50:19 UTC (releng/9.1, 9.1-RELEASE-p19)
|
|
2014-09-16 09:49:11 UTC (stable/8, 8.4-STABLE)
|
|
2014-09-16 09:50:19 UTC (releng/8.4, 8.4-RELEASE-p16)
|
|
CVE Name: CVE-2004-0230
|
|
|
|
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
|
|
|
|
The Transmission Control Protocol (TCP) of the TCP/IP protocol suite
|
|
provides a connection-oriented, reliable, sequence-preserving data
|
|
stream service. New TCP connections are initiated using special SYN
|
|
flag in a datagram. Sequencing of data is controlled by 32-bit sequence
|
|
numbers, that start with a random value and are increased using modulo
|
|
2**32 arithmetic. TCP endpoints maintain a window of expected, and
|
|
thus allowed, sequence numbers for a connection.
|
|
|
|
II. Problem Description
|
|
|
|
When a segment with the SYN flag for an already existing connection arrives,
|
|
the TCP stack tears down the connection, bypassing a check that the
|
|
sequence number in the segment is in the expected window.
|
|
|
|
III. Impact
|
|
|
|
An attacker who has the ability to spoof IP traffic can tear down a
|
|
TCP connection by sending only 2 packets, if they know both TCP port
|
|
numbers. In case one of the two port numbers is unknown, a successful
|
|
attack requires less than 2**17 packets spoofed, which can be
|
|
generated within less than a second on a decent connection to the
|
|
Internet.
|
|
|
|
IV. Workaround
|
|
|
|
It is possible to defend against these attacks with stateful traffic
|
|
inspection using a firewall. This can be done by enabling pf(4) on
|
|
the system and creating states for every connection. Even a default
|
|
ruleset to allow all traffic would be sufficient to mitigate this
|
|
issue.
|
|
|
|
V. Solution
|
|
|
|
Perform one of the following:
|
|
|
|
1) Upgrade your vulnerable system to a supported FreeBSD stable or
|
|
release / security branch (releng) dated after the correction date.
|
|
|
|
2) To update your vulnerable system via a source code patch:
|
|
|
|
The following patches have been verified to apply to the applicable
|
|
FreeBSD release branches.
|
|
|
|
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-14:19/tcp.patch
|
|
# fetch http://security.FreeBSD.org/patches/SA-14:19/tcp.patch.asc
|
|
# gpg --verify tcp.patch.asc
|
|
|
|
b) Apply the patch. Execute the following commands as root:
|
|
|
|
# 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
|
|
system.
|
|
|
|
3) To update your vulnerable system via a binary patch:
|
|
|
|
Systems running a RELEASE version of FreeBSD on the i386 or amd64
|
|
platforms can be updated via the freebsd-update(8) utility:
|
|
|
|
# freebsd-update fetch
|
|
# freebsd-update install
|
|
|
|
VI. Correction details
|
|
|
|
The following list contains the correction revision numbers for each
|
|
affected branch.
|
|
|
|
Branch/path Revision
|
|
- -------------------------------------------------------------------------
|
|
stable/8/ r271668
|
|
releng/8.4/ r271669
|
|
stable/9/ r271668
|
|
releng/9.1/ r271669
|
|
releng/9.2/ r271669
|
|
releng/9.3/ r271669
|
|
stable/10/ r271667
|
|
releng/10.0/ r271669
|
|
- -------------------------------------------------------------------------
|
|
|
|
To see which files were modified by a particular revision, run the
|
|
following command, replacing NNNNNN with the revision number, on a
|
|
machine with Subversion installed:
|
|
|
|
# svn diff -cNNNNNN --summarize svn://svn.freebsd.org/base
|
|
|
|
Or visit the following URL, replacing NNNNNN with the revision number:
|
|
|
|
<URL:http://svnweb.freebsd.org/base?view=revision&revision=NNNNNN>
|
|
|
|
VII. References
|
|
|
|
<URL:http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2004-0230>
|
|
|
|
The latest revision of this advisory is available at
|
|
<URL:http://security.FreeBSD.org/advisories/FreeBSD-SA-14:19.tcp.asc>
|
|
-----BEGIN PGP SIGNATURE-----
|
|
|
|
iQIcBAEBCgAGBQJUGAnEAAoJEO1n7NZdz2rnHEkP/0fVx7U6l/YKVWToejpCxMLa
|
|
TS9ng0kN5GEkyYPTHbK3Pb5T2b4zhpDlhRVTDtwkP+00VXAGIAC6GiQl2QBAApgv
|
|
68cla+TU+gh2I03XxIl+eWHu4EWaYa0v2vDqL0n/XNLvcZVD3R0CC+6HHUbKm46t
|
|
dQg4olCdXdHkZleclvuYGjd+W8JfC17Xe3xshNKq7BV05XWqXrKoqxfxot8Cnxyx
|
|
n4MePoiNYn13iO5OpEWf2J6BS1JJ1M/L0CAAKGcNitD8dYMdKNEfn6tpPXHNIWGH
|
|
vUI0sD2rPRs3OWbK6Y3xmakCPK8MXjSyFNvJ2NkuU6dYdKBNHYswh46F9XP0cSDc
|
|
K5wB36R/mx5ky05HBCpAjiGh2X67Y6QtQiBq5ESltodAp1Sl966fgLnNKyIgeHr5
|
|
51QNCXDdc7S7pE9daA/uiIEZVKH8eKYGHP53zN/tiTDVWy7yTEBIW4lhJVkHIAAt
|
|
VBvLB0efr47z6IZ92GshGKZawaPAOeuBrEtYDOdNNJeh+WhSPoE5MKfS6NiH/lRg
|
|
DorewB9KbChCUhxMCH2Pj7AxTVoe3fjWtZYRo02OHMitTTJbExsyT33vTH1Sb2LT
|
|
6lXBFFOvo5Uw8JJyykd+GXUcwe13hcroS+eqz/GE+9yReMrwd82qbiDM4VlTdVMq
|
|
trAqOw2zRyBa7R6D2+4T
|
|
=qjIZ
|
|
-----END PGP SIGNATURE-----
|