3571e53040
patches for easier mirroring, to eliminate a special copy, to make www.freebsd.org/security a full copy of security.freebsd.org and be eventually be the same. For now files are just sitting there. The symlinks are missing. Discussed on: www (repository location) Discussed with: simon (so)
109 lines
3.6 KiB
Text
109 lines
3.6 KiB
Text
-----BEGIN PGP SIGNED MESSAGE-----
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Hash: SHA1
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=============================================================================
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FreeBSD-SA-06:08.sack Security Advisory
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The FreeBSD Project
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Topic: Infinite loop in SACK handling
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Category: core
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Module: netinet
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Announced: 2006-02-01
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Credits: Scott Wood
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Affects: FreeBSD 5.3 and 5.4
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Corrected: 2006-01-24 01:16:18 UTC (RELENG_5, 5.4-STABLE)
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2006-02-01 19:43:10 UTC (RELENG_5_4, 5.4-RELEASE-p11)
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2006-02-01 19:43:36 UTC (RELENG_5_3, 5.3-RELEASE-p26)
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CVE Name: CVE-2006-0433
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For general information regarding FreeBSD Security Advisories,
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including descriptions of the fields above, security branches, and the
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following sections, please visit
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<URL:http://www.freebsd.org/security/>.
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I. Background
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SACK (Selective Acknowledgement) is an extension to the TCP/IP protocol
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that allows hosts to acknowledge the receipt of some, but not all, of
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the packets sent, thereby reducing the cost of retransmissions.
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II. Problem Description
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When insufficient memory is available to handle an incoming selective
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acknowledgement, the TCP/IP stack may enter an infinite loop.
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III. Impact
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By opening a TCP connection and sending a carefully crafted series of
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packets, an attacker may be able to cause a denial of service.
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IV. Workaround
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On FreeBSD 5.4, the net.inet.tcp.sack.enable sysctl can be used to
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disable the use of SACK:
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# sysctl net.inet.tcp.sack.enable=0
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No workaround is available for FreeBSD 5.3.
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V. Solution
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Perform one of the following:
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1) Upgrade your vulnerable system to 5-STABLE or to the RELENG_5_4 or
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RELENG_5_3 security branch dated after the correction date.
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2) To patch your present system:
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The following patch have been verified to apply to FreeBSD 5.3 and
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5.4 systems.
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a) Download the relevant patch from the location below, and verify the
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detached PGP signature using your PGP utility.
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# fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-06:08/sack.patch
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# fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-06:08/sack.patch.asc
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b) Apply the patch.
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# cd /usr/src
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# patch < /path/to/patch
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c) Recompile your kernel as described in
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<URL:http://www.freebsd.org/handbook/kernelconfig.html> and reboot the
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system.
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VI. Correction details
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The following list contains the revision numbers of each file that was
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corrected in FreeBSD.
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Branch Revision
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Path
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- -------------------------------------------------------------------------
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RELENG_5
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src/sys/netinet/tcp_sack.c 1.3.2.10
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RELENG_5_4
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src/UPDATING 1.342.2.24.2.20
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src/sys/conf/newvers.sh 1.62.2.18.2.16
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src/sys/netinet/tcp_sack.c 1.3.2.5.2.1
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RELENG_5_3
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src/UPDATING 1.342.2.13.2.29
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src/sys/conf/newvers.sh 1.62.2.15.2.31
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src/sys/netinet/tcp_sack.c 1.3.4.1
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- -------------------------------------------------------------------------
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VII. References
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http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2006-0433
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The latest revision of this advisory is available at
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ftp://ftp.freebsd.org/pub/FreeBSD/CERT/advisories/FreeBSD-SA-06:08.sack.asc
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