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)
150 lines
5.7 KiB
Text
150 lines
5.7 KiB
Text
-----BEGIN PGP SIGNED MESSAGE-----
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=============================================================================
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FreeBSD-SA-01:51 Security Advisory
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FreeBSD, Inc.
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Topic: OpenSSL 0.9.6a and earlier contain flaw in PRNG [REVISED]
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Category: core
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Module: openssl
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Announced: 2001-07-30
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Revised: 2001-07-31
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Credits: Markku-Juhani O. Saarinen <markku-juhani.saarinen@nokia.com>
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The OpenSSL Project <URL:http://www.openssl.org/>
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Affects: All releases of FreeBSD 4.x prior to 4.4,
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FreeBSD 4.3-STABLE prior to the correction date
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Corrected: 2001-07-19 21:00:45 UTC (FreeBSD 4.3-STABLE)
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2001-07-19 21:01:08 UTC (FreeBSD 4.3-SECURITY aka RELENG_4_3)
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FreeBSD only: NO
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0. Revision History
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v1.0 2001-07-30 Initial release
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v1.1 2001-07-31 Corrected patch instructions
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I. Background
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FreeBSD includes software from the OpenSSL Project. The OpenSSL
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Project is a collaborative effort to develop a robust,
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commercial-grade, full-featured, and Open Source toolkit implementing
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the Secure Sockets Layer (SSL v2/v3) and Transport Layer Security (TLS
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v1) protocols as well as a full-strength general purpose cryptography
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library.
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II. Problem Description
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A flaw in the pseudo-random number generator (PRNG) of OpenSSL
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versions previous to 0.9.6b allows an attacker to determine the PRNG
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state and future output under certain restricted conditions, thereby
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weakening the strength of the PRNG and any cryptographic protection
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which is derived from it. In effect, the flaw is that a portion of
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the PRNG state is incorrectly used as the PRNG output, allowing
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attackers to gain knowledge of the internal state of the PRNG by
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observing the output if they can sample it in a certain way.
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An attack taking advantage of this flaw has been identified that can
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recover the complete state of the PRNG from the output of one
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carefully sized PRNG request followed by a few hundred consecutive
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1-byte PRNG requests.
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This access pattern is not typically obtainable in real-world uses of
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the PRNG in cryptographic protocols, and no exploit against a protocol
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supported by OpenSSL is currently known.
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III. Impact
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By successfully exploiting a flaw in the PRNG, an attacker can gain
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important information that may allow him to deduce nonces (leading to
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the compromise of the protocol session) or encryption keys (allowing
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the attacker to obtain the plaintext of the encrypted data).
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Whether or not this flaw is exploitable depends upon the specifics of
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the application using OpenSSL. No vulnerable applications or
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protocols are currently known.
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IV. Workaround
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None applicable.
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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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4.3-SECURITY (aka RELENG_4_3) security branch after the respective
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correction dates.
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2) FreeBSD 4.x systems prior to the correction date:
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The following patch have 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. These patches may or may not apply to older, unsupported
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releases 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-01:51/openssl.patch
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ftp://ftp.freebsd.org/pub/FreeBSD/CERT/patches/SA-01:51/openssl.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/secure/lib/libcrypto/
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# make depend && make all install
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One must also recompile any statically linked applications that use
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OpenSSL's PRNG. 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 files
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which are replaced by the package. These backup copies will be
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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-01:51/security-patch-openssl-01.51.tgz
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# fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/packages/SA-01:51/security-patch-openssl-01.51.tgz.asc
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Verify the detached PGP signature using your PGP utility.
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# pkg_add security-patch-openssl-01.51.tgz
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VI. Correction details
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The following list contains the revision numbers of each file that was
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corrected for the maintained versions of FreeBSD.
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FreeBSD Version and CVS Tag
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Path Revision
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- -------------------------------------------------------------------------
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FreeBSD 4.3-SECURITY (tag: RELENG_4_3)
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src/crypto/openssl/crypto/rand/md_rand.c 1.1.1.1.2.2.2.1
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FreeBSD 4.3-STABLE (tag: RELENG_4)
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src/crypto/openssl/crypto/rand/md_rand.c 1.1.1.1.2.4
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- -------------------------------------------------------------------------
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VII. References
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<URL:http://www.openssl.org/source/exp/CHANGES>
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<URL:http://www.securityfocus.com/bid/3004>
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-----BEGIN PGP SIGNATURE-----
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Version: GnuPG v1.0.6 (FreeBSD)
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Comment: For info see http://www.gnupg.org
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=R/xp
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-----END PGP SIGNATURE-----
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