Date: Tue, 2 Mar 2004 12:06:14 -0800 (PST) From: Daniel Spielman <dan@dreadful.org> To: freebsd-security@FreeBSD.org Subject: Re: FreeBSD Security Advisory FreeBSD-SA-04:04.tcp Message-ID: <20040302120455.S38344@dreadful.org> In-Reply-To: <200403021955.i22Jtix2024059@freefall.freebsd.org> References: <200403021955.i22Jtix2024059@freefall.freebsd.org>
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is FreeBSD 5.2.1 affected by this exploit ? On Tue, 2 Mar 2004, FreeBSD Security Advisories wrote: > -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA1 > > ============================================================================= > 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=vulnerabilities>; > -----BEGIN PGP SIGNATURE----- > Version: GnuPG v1.2.4 > > iD8DBQFAROKHFdaIBMps37IRAu9EAJ9VY70IDYdjr6GkKJCJCGyvBV3OcQCeIXwL > UDTQ4rcO/SP2rFRZ0Mcj1iQ= > =Gkct > -----END PGP SIGNATURE----- > _______________________________________________ > freebsd-security@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-security > To unsubscribe, send any mail to "freebsd-security-unsubscribe@freebsd.org" >
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