145 lines
5.4 KiB
Text
145 lines
5.4 KiB
Text
-----BEGIN PGP SIGNED MESSAGE-----
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Hash: SHA512
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=============================================================================
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FreeBSD-SA-17:05.heimdal Security Advisory
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The FreeBSD Project
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Topic: heimdal KDC-REP service name validation vulnerability
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Category: contrib
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Module: heimdal
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Announced: 2017-07-12
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Affects: All supported versions of FreeBSD.
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Corrected: 2017-07-12 07:26:07 UTC (stable/11, 11.1-PRERELEASE)
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2017-07-12 08:07:16 UTC (releng/11.1, 11.1-RC2-p1)
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2017-07-12 08:07:16 UTC (releng/11.1, 11.1-RC1-p1)
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2017-07-12 07:26:07 UTC (stable/11, 11.1-BETA3-p1)
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2017-07-12 08:07:36 UTC (releng/11.0, 11.0-RELEASE-p11)
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2017-07-12 07:26:07 UTC (stable/10, 10.3-STABLE)
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2017-07-12 15:16:01 UTC (releng/10.3, 10.3-RELEASE-p20)
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CVE Name: CVE-2017-11103
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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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I. Background
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Heimdal implements the Kerberos 5 network authentication protocols.
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The Kerberos protocol uses "tickets" to authenticate a client to a
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service.
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A Key Distribution Center (KDC) is trusted by all principals registered
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in that administrative "realm" to store a secret key in confidence, of
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which, the proof of knowledge is used to verify the authenticity of a
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principal.
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II. Problem Description
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There is a programming error in the Heimdal implementation that used an
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unauthenticated, plain-text version of the KDC-REP service name found
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in a ticket.
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III. Impact
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An attacker who has control of the network between a client and the
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service it talks to will be able to impersonate the service, allowing
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a successful man-in-the-middle (MITM) attack that circumvents the mutual
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authentication.
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IV. Workaround
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No workaround is available, but only Kerberos enabled clients are
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affected.
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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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A reboot is recommended.
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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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A reboot is recommended.
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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 https://security.FreeBSD.org/patches/SA-17:05/heimdal.patch
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# fetch https://security.FreeBSD.org/patches/SA-17:05/heimdal.patch.asc
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# gpg --verify heimdal.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/10/ r320907
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releng/10.3/ r320915
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stable/11/ r320907
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releng/11.0/ r320911
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releng/11.1/ r320910
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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:https://www.orpheus-lyre.info/>
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<URL:https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2017-11103>
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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-17:05.heimdal.asc>
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