[olug] Fw: FreeBSD Security Advisory FreeBSD-SA-04:04.tcp
Jeff Hinrichs
jlh at cox.net
Tue Mar 2 20:54:47 UTC 2004
fyi: cvsup; make buildkernel; make installkernel; reboot
----- Original Message -----
From: "FreeBSD Security Advisories" <security-advisories at freebsd.org>
To: "FreeBSD Security Advisories" <security-advisories at freebsd.org>
Sent: Tuesday, March 02, 2004 1:55 PM
Subject: FreeBSD Security Advisory FreeBSD-SA-04:04.tcp
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============================================================================
=
> FreeBSD-SA-04:04.tcp Security
Advisory
> The FreeBSD
Project
>
> Topic: many out-of-sequence TCP packets denial-of-service
>
> Category: core
> Module: kernel
> Announced: 2004-03-02
> Credits: iDEFENSE
> Affects: All FreeBSD releases
> Corrected: 2004-03-02 17:19:18 UTC (RELENG_4)
> 2004-03-02 17:24:46 UTC (RELENG_5_2, 5.2.1-RELEASE-p1)
> 2004-03-02 17:26:33 UTC (RELENG_4_9, 4.9-RELEASE-p3)
> 2004-03-02 17:27:47 UTC (RELENG_4_8, 4.8-RELEASE-p16)
> CVE Name: CAN-2004-0171
> FreeBSD only: NO
>
> I. Background
>
> The Transmission Control Protocol (TCP) of the TCP/IP protocol suite
> provides a connection-oriented, reliable, sequence-preserving data
> stream service. When network packets making up a TCP stream (``TCP
> segments'') are received out-of-sequence, they are maintained in a
> reassembly queue by the destination system until they can be re-ordered
> and re-assembled.
>
> II. Problem Description
>
> FreeBSD does not limit the number of TCP segments that may be held in a
> reassembly queue.
>
> III. Impact
>
> A remote attacker may conduct a low-bandwidth denial-of-service attack
> against a machine providing services based on TCP (there are many such
> services, including HTTP, SMTP, and FTP). By sending many
> out-of-sequence TCP segments, the attacker can cause the target machine
> to consume all available memory buffers (``mbufs''), likely leading to
> a system crash.
>
> IV. Workaround
>
> It may be possible to mitigate some denial-of-service attacks by
> implementing timeouts at the application level.
>
> V. Solution
>
> Do one of the following:
>
> 1) Upgrade your vulnerable system to 4-STABLE, or to the RELENG_5_2,
> RELENG_4_9, or RELENG_4_8 security branch dated after the correction
> date.
>
> OR
>
> 2) Patch your present system:
>
> The following patch has been verified to apply to FreeBSD 4.x and 5.x
> systems.
>
> a) Download the relevant patch from the location below, and verify the
> detached PGP signature using your PGP utility.
>
> [FreeBSD 5.2]
> # fetch
ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-04:04/tcp52.patch
> # fetch
ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-04:04/tcp52.patch.asc
>
> [FreeBSD 4.8, 4.9]
> # fetch
ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-04:04/tcp47.patch
> # fetch
ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-04:04/tcp47.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
> system.
>
> VI. Correction details
>
> The following list contains the revision numbers of each file that was
> corrected in FreeBSD.
>
> Branch Revision
> Path
> - ------------------------------------------------------------------------
-
> RELENG_4
> src/UPDATING 1.73.2.90
> src/sys/conf/newvers.sh 1.44.2.33
> src/sys/netinet/tcp_input.c 1.107.2.40
> src/sys/netinet/tcp_subr.c 1.73.2.33
> src/sys/netinet/tcp_var.h 1.56.2.15
> RELENG_5_2
> src/UPDATING 1.282.2.9
> src/sys/conf/newvers.sh 1.56.2.8
> src/sys/netinet/tcp_input.c 1.217.2.2
> src/sys/netinet/tcp_subr.c 1.169.2.4
> src/sys/netinet/tcp_var.h 1.93.2.2
> RELENG_4_9
> src/UPDATING 1.73.2.89.2.4
> src/sys/conf/newvers.sh 1.44.2.32.2.4
> src/sys/netinet/tcp_input.c 1.107.2.38.2.1
> src/sys/netinet/tcp_subr.c 1.73.2.31.4.1
> src/sys/netinet/tcp_var.h 1.56.2.13.4.1
> RELENG_4_8
> src/UPDATING 1.73.2.80.2.19
> src/sys/conf/newvers.sh 1.44.2.29.2.17
> src/sys/netinet/tcp_input.c 1.107.2.37.2.1
> src/sys/netinet/tcp_subr.c 1.73.2.31.2.1
> src/sys/netinet/tcp_var.h 1.56.2.13.2.1
> - ------------------------------------------------------------------------
-
>
> VII. References
>
>
<URL:http://www.idefense.com/application/poi/display?id=78&type=vulnerabilit
ies>
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