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)
135 lines
4.6 KiB
Text
135 lines
4.6 KiB
Text
-----BEGIN PGP SIGNED MESSAGE-----
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=============================================================================
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FreeBSD-SA-01:56 Security Advisory
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FreeBSD, Inc.
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Topic: tcp_wrappers PARANOID hostname checking does not work
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Category: core
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Module: tcp_wrappers
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Announced: 2001-08-23
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Credits: Tony Finch <dot@dotat.at>
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Affects: FreeBSD 4.1.1-RELEASE
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FreeBSD 4.2-RELEASE
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FreeBSD 4.3-RELEASE
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FreeBSD 4.3-STABLE before the correction date
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Corrected: 2001-07-04 20:18:11 UTC (FreeBSD 4.3-STABLE)
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2001-07-04 20:18:54 UTC (RELENG_4_3)
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FreeBSD only: Yes
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I. Background
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FreeBSD has included Wietse Venema's tcp_wrappers since 3.2-RELEASE.
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tcp_wrappers allows one to add host-based ACLs to network
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applications, and additionally provides connection logging and some
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detection of DNS spoofing.
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II. Problem Description
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The addition of a flawed check for a numeric result during reverse DNS
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lookup causes tcp_wrappers to skip some of its sanity checking of DNS
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results. These sanity checks are only enabled by the 'PARANOID' ACL
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option in the configuration file, and simply weaken the 'PARANOID'
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host checks to the level of assurance provided by the regular host
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ACLs.
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This vulnerability was corrected prior to the (forthcoming) release of
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FreeBSD 4.4-RELEASE.
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III. Impact
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An attacker that can influence the results of reverse DNS lookups can
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bypass certain tcp_wrappers PARANOID ACL restrictions by impersonating
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a trusted host. Such an attacker would need to be able to spoof
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reverse DNS lookups, or more simply the attacker may be the
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administrator of the DNS zone including the IP address of the remote
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host.
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IV. Workaround
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None.
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V. Solution
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One of the following:
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1) Upgrade your vulnerable FreeBSD system to 4.3-STABLE or the
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RELENG_4_3 security branch after the respective correction dates.
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2) FreeBSD 4.x systems prior to the correction date:
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The following patche has been verified to apply to FreeBSD
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4.2-RELEASE, 4.3-RELEASE and 4.3-STABLE dated prior to the correction
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date. This patch may or may not apply to older, unsupported releases
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of FreeBSD.
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Download the patch and the detached PGP signature from the following
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locations, and verify the signature using your PGP utility.
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ftp://ftp.freebsd.org/pub/FreeBSD/CERT/patches/SA-01:56/tcp_wrappers.patch
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ftp://ftp.freebsd.org/pub/FreeBSD/CERT/patches/SA-01:56/tcp_wrappers.patch.asc
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# cd /usr/src/
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# patch -p < /path/to/patch
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# cd /usr/src/lib/libwrap
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# make depend && make all install
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One must also recompile any statically linked applications that link
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against libwrap.a. There are no such applications in the base system.
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3) FreeBSD 4.3-RELEASE systems:
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An experimental upgrade package is available for users who wish to
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provide testing and feedback on the binary upgrade process. This
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package may be installed on FreeBSD 4.3-RELEASE systems only, and is
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intended for use on systems for which source patching is not practical
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or convenient.
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If you use the upgrade package, feedback (positive or negative) to
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security-officer@FreeBSD.org is requested so we can improve the
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process for future advisories.
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During the installation procedure, backup copies are made of the
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files which are replaced by the package. These backup copies will
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be reinstalled if the package is removed, reverting the system to a
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pre-patched state.
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# fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/packages/SA-01:56/security-patch-tcp_wrappers-01.56.tgz
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# fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/packages/SA-01:56/security-patch-tcp_wrappers-01.56.tgz.asc
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Verify the detached PGP signature using your PGP utility.
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# pkg_add security-patch-tcp_wrappers-01.56.tgz
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VI. Correction details
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The following list contains the $FreeBSD$ revision numbers of each
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file that was corrected, for the supported branches of FreeBSD. The
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$FreeBSD$ revision of installed sources can be examined using the
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ident(1) command. The patch provided above does not cause these
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revision numbers to be updated.
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[FreeBSD 4.3-STABLE]
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Revision Path
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1.2.2.3 src/contrib/tcp_wrappers/socket.c
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[RELENG_4_3]
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Revision Path
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1.2.2.2.2.1 src/contrib/tcp_wrappers/socket.c
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VII. References
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<URL:http://www.freebsd.org/cgi/cvsweb.cgi/src/contrib/tcp_wrappers/socket.c#rev1.6>
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