169 lines
6.6 KiB
Text
169 lines
6.6 KiB
Text
-----BEGIN PGP SIGNED MESSAGE-----
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Hash: SHA1
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=============================================================================
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FreeBSD-SA-14:20.rtsold Security Advisory
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The FreeBSD Project
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Topic: rtsold(8) remote buffer overflow vulnerability
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Category: core
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Module: rtsold
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Announced: 2014-10-21
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Credits: Florian Obser, Hiroki Sato
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Affects: FreeBSD 9.1 and later.
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Corrected: 2014-10-21 20:20:07 UTC (stable/10, 10.1-PRERELEASE)
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2014-10-21 20:20:36 UTC (releng/10.1, 10.1-RC2-p1)
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2014-10-21 20:20:36 UTC (releng/10.1, 10.1-RC1-p1)
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2014-10-21 20:20:36 UTC (releng/10.1, 10.1-BETA3-p1)
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2014-10-21 20:21:10 UTC (releng/10.0, 10.0-RELEASE-p10)
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2014-10-21 20:20:17 UTC (stable/9, 9.3-STABLE)
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2014-10-21 20:21:10 UTC (releng/9.3, 9.3-RELEASE-p3)
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2014-10-21 20:21:10 UTC (releng/9.2, 9.2-RELEASE-p13)
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2014-10-21 20:21:10 UTC (releng/9.1, 9.1-RELEASE-p20)
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CVE Name: CVE-2014-3954
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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 <URL:http://security.FreeBSD.org/>.
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I. Background
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As part of the stateless addess autoconfiguration (SLAAC) mechanism,
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IPv6 routers periodically broadcast router advertisement messages on
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attached networks to inform hosts of the correct network prefix,
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router address and MTU, as well as additional network parameters such
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as the DNS servers (RDNSS), DNS search list (DNSSL) and whether a
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stateful configuration service is available. Hosts that have recently
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joined the network can broadcast a router solicitation message to
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solicit an immediate advertisement instead of waiting for the next
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periodic advertisement.
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The router solicitation daemon, rtsold(8), broadcasts router
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solicitation messages at startup or when the state of an interface
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changes from passive to active. Incoming router advertisement
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messages are first processed by the kernel and then passed on to
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rtsold(8), which handles the DNS and stateful configuration options.
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II. Problem Description
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Due to a missing length check in the code that handles DNS parameters,
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a malformed router advertisement message can result in a stack buffer
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overflow in rtsold(8).
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III. Impact
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Receipt of a router advertisement message with a malformed DNSSL
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option, for instance from a compromised host on the same network, can
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cause rtsold(8) to crash.
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While it is theoretically possible to inject code into rtsold(8)
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through malformed router advertisement messages, it is normally
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compiled with stack protection enabled, rendering such an attack
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extremely difficult.
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When rtsold(8) crashes, the existing DNS configuration will remain in
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force, and the kernel will continue to receive and process periodic
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router advertisements.
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IV. Workaround
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No workaround is available, but systems that do not run rtsold(8) are
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not affected.
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As a general rule, SLAAC should not be used on networks where trusted
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and untrusted hosts coexist in the same broadcast domain.
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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 a supported FreeBSD stable or
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release / security branch (releng) dated after the correction date.
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2) To update your vulnerable system via a binary patch:
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Systems running a RELEASE version of FreeBSD on the i386 or amd64
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platforms can be updated via the freebsd-update(8) utility:
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# freebsd-update fetch
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# freebsd-update install
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3) To update your vulnerable system via a source code patch:
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The following patches have been verified to apply to the applicable
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FreeBSD release branches.
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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 http://security.FreeBSD.org/patches/SA-14:20/rtsold.patch
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# fetch http://security.FreeBSD.org/patches/SA-14:20/rtsold.patch.asc
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# gpg --verify rtsold.patch.asc
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b) Apply the patch. Execute the following commands as root:
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# cd /usr/src
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# patch < /path/to/rtsold.patch
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c) Recompile rtsold. Execute the following commands as root:
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# cd /usr/src/usr.sbin/rtsold
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# make && make install
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4) Restart the affected service
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To restart the affected service after updating the system, either
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reboot the system or execute the following command as root:
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# service rtsold restart
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VI. Correction details
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The following list contains the correction revision numbers for each
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affected branch.
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Branch/path Revision
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- -------------------------------------------------------------------------
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stable/9/ r273412
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releng/9.1/ r273415
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releng/9.2/ r273415
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releng/9.3/ r273415
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stable/10/ r273411
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releng/10.0/ r273415
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releng/10.1/ r273414
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- -------------------------------------------------------------------------
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To see which files were modified by a particular revision, run the
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following command, replacing NNNNNN with the revision number, on a
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machine with Subversion installed:
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# svn diff -cNNNNNN --summarize svn://svn.freebsd.org/base
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Or visit the following URL, replacing NNNNNN with the revision number:
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<URL:http://svnweb.freebsd.org/base?view=revision&revision=NNNNNN>
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VII. References
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<URL:http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2014-3954>
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The latest revision of this advisory is available at
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<URL:http://security.FreeBSD.org/advisories/FreeBSD-SA-14:20.rtsold.asc>
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