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)
105 lines
3.5 KiB
Text
105 lines
3.5 KiB
Text
-----BEGIN PGP SIGNED MESSAGE-----
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Hash: SHA1
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=============================================================================
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FreeBSD-SA-06:04.ipfw Security Advisory
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The FreeBSD Project
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Topic: ipfw IP fragment denial of service
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Category: core
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Module: ipfw
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Announced: 2006-01-11
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Credits: Oleg Bulyzhin
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Affects: FreeBSD 6.0-RELEASE
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Corrected: 2006-01-11 08:02:16 UTC (RELENG_6, 6.0-STABLE)
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2006-01-11 08:03:18 UTC (RELENG_6_0, 6.0-RELEASE-p2)
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CVE Name: CVE-2006-0054
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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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ipfw(8) is a system facility which provides IP packet filtering,
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accounting, and redirection. Among the many features, while discarding
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packets it can perform actions defined by the user, such as sending
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back TCP reset or ICMP unreachable packets. These operations can be
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performed by using the reset, reject or uncreach actions.
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II. Problem Description
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The firewall maintains a pointer to layer 4 header information in the
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event that it needs to send a TCP reset or ICMP error message to
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discard packets. Due to incorrect handling of IP fragments, this
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pointer fails to get initialized.
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III. Impact
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An attacker can cause the firewall to crash by sending ICMP IP
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fragments to or through firewalls which match any reset, reject or
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unreach actions.
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IV. Workaround
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Change any reset, reject or unreach actions to deny. It should be
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noted that this will result in packets being silently discarded.
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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 6-STABLE or to the RELENG_6_0
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security branch dated after the correction date.
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2) To patch your present system:
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The following patches have been verified to apply to FreeBSD 6.0
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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-06:04/ipfw.patch
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# fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-06:04/ipfw.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_6
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src/sys/netinet/ip_fw2.c 1.106.2.6
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RELENG_6_0
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src/UPDATING 1.416.2.3.2.7
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src/sys/conf/newvers.sh 1.69.2.8.2.3
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src/sys/netinet/ip_fw2.c 1.106.2.3.2.1
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- -------------------------------------------------------------------------
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VII. References
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http://cve.mitre.org/cgi-bin/cvename.cgi?name=CAN-2006-0054
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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-06:04.ipfw.asc
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