159 lines
6 KiB
Text
159 lines
6 KiB
Text
-----BEGIN PGP SIGNED MESSAGE-----
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Hash: SHA512
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=============================================================================
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FreeBSD-SA-16:11.openssl Security Advisory
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The FreeBSD Project
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Topic: OpenSSL SSLv2 ciphersuite downgrade vulnerability
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Category: contrib
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Module: openssl
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Announced: 2016-01-30
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Affects: All supported versions of FreeBSD.
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Corrected: 2016-01-28 21:42:10 UTC (stable/10, 10.2-STABLE)
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2016-01-30 06:12:03 UTC (releng/10.2, 10.2-RELEASE-p12)
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2016-01-30 06:12:03 UTC (releng/10.1, 10.1-RELEASE-p29)
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2016-01-30 06:09:38 UTC (stable/9, 9.3-STABLE)
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2016-01-30 06:12:03 UTC (releng/9.3, 9.3-RELEASE-p36)
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CVE Name: CVE-2015-3197
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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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FreeBSD includes software from the OpenSSL Project. The OpenSSL Project is
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a collaborative effort to develop a robust, commercial-grade, full-featured
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Open Source toolkit implementing the Secure Sockets Layer (SSL v2/v3)
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and Transport Layer Security (TLS v1) protocols as well as a full-strength
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general purpose cryptography library.
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II. Problem Description
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A malicious client can negotiate SSLv2 ciphers that have been disabled on
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the server and complete SSLv2 handshakes even if all SSLv2 ciphers have
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been disabled, provided that the SSLv2 protocol was not also disabled via
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SSL_OP_NO_SSLv2.
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III. Impact
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An active MITM attacker may be able to force a protocol downgrade to SSLv2,
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which is a flawed protocol and intercept the communication between client
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and server.
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IV. Workaround
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No workaround is available, but only applications that do not explicitly
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disable SSLv2 are affected.
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To determine if a server have SSLv2 enabled, a system administrator can
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use the following command:
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% openssl s_client -ssl2 -connect <host>:<port> </dev/null 2>&1 | grep DONE
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which will print "DONE" if and only if SSLv2 is enabled. Note that this
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check will not work for services that uses STARTTLS or DTLS.
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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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Restart all deamons using the library, or reboot the system.
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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 deamons using 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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[FreeBSD 10.2]
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# fetch https://security.FreeBSD.org/patches/SA-16:11/openssl-10.2.patch
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# fetch https://security.FreeBSD.org/patches/SA-16:11/openssl-10.2.patch.asc
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# gpg --verify openssl-10.2.patch.asc
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[FreeBSD 10.1]
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# fetch https://security.FreeBSD.org/patches/SA-16:11/openssl-10.1.patch
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# fetch https://security.FreeBSD.org/patches/SA-16:11/openssl-10.1.patch.asc
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# gpg --verify openssl-10.1.patch.asc
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[FreeBSD 9.3]
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# fetch https://security.FreeBSD.org/patches/SA-16:11/openssl-9.3.patch
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# fetch https://security.FreeBSD.org/patches/SA-16:11/openssl-9.3.patch.asc
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# gpg --verify openssl-9.3.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 deamons using 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/ r295060
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releng/9.3/ r295061
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stable/10/ r295016
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releng/10.1/ r295061
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releng/10.2/ r295061
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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.openssl.org/news/secadv/20160128.txt>
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<URL:https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2015-3197>
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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-16:11.openssl.asc>
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