156 lines
6.2 KiB
Text
156 lines
6.2 KiB
Text
-----BEGIN PGP SIGNED MESSAGE-----
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Hash: SHA512
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=============================================================================
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FreeBSD-SA-16:37.libc Security Advisory
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The FreeBSD Project
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Topic: link_ntoa(3) buffer overflow
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Category: core
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Module: libc
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Announced: 2016-12-06, revised on 2016-12-08
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Affects: All supported versions of FreeBSD.
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Corrected: 2016-12-07 23:19:46 UTC (stable/11, 11.0-STABLE)
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2016-12-07 23:29:42 UTC (releng/11.0, 11.0-RELEASE-p5)
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2016-12-07 23:20:26 UTC (stable/10, 10.3-STABLE)
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2016-12-07 23:31:07 UTC (releng/10.3, 10.3-RELEASE-p14)
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2016-12-07 23:32:42 UTC (releng/10.2, 10.2-RELEASE-p27)
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2016-12-07 23:34:06 UTC (releng/10.1, 10.1-RELEASE-p44)
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2016-12-07 23:20:50 UTC (stable/9, 9.3-STABLE)
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2016-12-07 23:35:15 UTC (releng/9.3, 9.3-RELEASE-p52)
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CVE Name: CVE-2016-6559
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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:https://security.FreeBSD.org/>.
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0. Revision history.
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v1.0 2016-12-06 Initial release.
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v1.1 2016-12-08 Revised patches to address regressions.
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I. Background
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The link_ntoa(3) function generates ASCII representation of a link-level
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address and is avaliable as part of standard C library (libc).
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II. Problem Description
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A specially crafted argument can trigger a static buffer overflow in the
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library, with possibility to rewrite following static buffers that belong to
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other library functions.
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III. Impact
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Due to very limited use of the function in the existing applications,
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and limited length of the overflow, exploitation of the vulnerability
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does not seem feasible. None of the utilities and daemons in the base
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system are known to be vulnerable. However, careful review of third
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party software that may use the function was not performed.
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IV. Workaround
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No workaround is available.
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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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Restart all daemons that use the library, or reboot the system.
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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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[*** v1.1 NOTE ***] If your sources are not yet patched using the initially
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published patch, then you need to apply libc.patch. If your sources are
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already updated, or patched with patch from the initial advisory, then you
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need to apply the incremental patch, named libc-inc.patch.
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[FreeBSD system, not patched with initial SA-16:37 patch]
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# fetch https://security.FreeBSD.org/patches/SA-16:37/libc.patch
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# fetch https://security.FreeBSD.org/patches/SA-16:37/libc.patch.asc
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# gpg --verify libc.patch.asc
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[FreeBSD system, initial SA-16:37 patch already applied]
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# fetch https://security.FreeBSD.org/patches/SA-16:37/libc-inc.patch
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# fetch https://security.FreeBSD.org/patches/SA-16:37/libc-inc.patch.asc
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# gpg --verify libc-inc.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/patch
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c) Recompile the operating system using buildworld and installworld as
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described in <URL:https://www.FreeBSD.org/handbook/makeworld.html>.
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Restart all daemons that use the library, or reboot the system.
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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/ r309691
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releng/9.3/ r309697
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stable/10/ r309690
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releng/10.1/ r309696
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releng/10.2/ r309694
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releng/10.3/ r309693
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stable/11/ r309689
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releng/11.0/ r309692
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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:https://svnweb.freebsd.org/base?view=revision&revision=NNNNNN>
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VII. References
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<URL:http://www.kb.cert.org/vuls/id/548487>
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<URL:https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2016-6559>
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<URL:https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=215105>
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The latest revision of this advisory is available at
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<URL:https://security.FreeBSD.org/advisories/FreeBSD-SA-16:37.libc.asc>
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