FreeBSD Security Advisory FreeBSD-SA-16:12.openssl

Fabricante: FreeBSD
Fecha: 10/03/2016
Identificador: FreeBSD-SA-16:12.openssl
FreeBSD Security Advisory FreeBSD-SA-16:12.openssl
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA512 ============================================================================= FreeBSD-SA-16:12.openssl Security Advisory The FreeBSD Project Topic: Multiple OpenSSL vulnerabilities Category: contrib Module: openssl Announced: 2016-03-10 Credits: OpenSSL Project Affects: All supported versions of FreeBSD. Corrected: 2016-03-04 00:40:15 UTC (stable/10, 10.2-BETA3) 2016-03-03 07:30:55 UTC (releng/10.2, 10.2-RELEASE-p13) 2016-03-03 07:30:55 UTC (releng/10.1, 10.1-RELEASE-p30) 2016-03-10 03:58:48 UTC (stable/9, 9.3-STABLE) 2016-03-10 10:03:28 UTC (releng/9.3, 9.3-RELEASE-p38) CVE Name: CVE-2016-0702, CVE-2016-0703, CVE-2016-0704, CVE-2016-0705 CVE-2016-0797, CVE-2016-0798, CVE-2016-0799, CVE-2016-0800 For general information regarding FreeBSD Security Advisories, including descriptions of the fields above, security branches, and the following sections, please visit . I. Background FreeBSD includes software from the OpenSSL Project. The OpenSSL Project is a collaborative effort to develop a robust, commercial-grade, full-featured Open Source toolkit implementing the Secure Sockets Layer (SSL v2/v3) and Transport Layer Security (TLS v1) protocols as well as a full-strength general purpose cryptography library. II. Problem Description A cross-protocol attack was discovered that could lead to decryption of TLS sessions by using a server supporting SSLv2 and EXPORT cipher suites as a Bleichenbacher RSA padding oracle. Note that traffic between clients and non-vulnerable servers can be decrypted provided another server supporting SSLv2 and EXPORT ciphers (even with a different protocol such as SMTP, IMAP or POP3) shares the RSA keys of the non-vulnerable server. This vulnerability is known as DROWN. [CVE-2016-0800] A double free bug was discovered when OpenSSL parses malformed DSA private keys and could lead to a DoS attack or memory corruption for applications that receive DSA private keys from untrusted sources. This scenario is considered rare. [CVE-2016-0705] The SRP user database lookup method SRP_VBASE_get_by_user had confusing memory management semantics; the returned pointer was sometimes newly allocated, and sometimes owned by the callee. The calling code has no way of distinguishing these two cases. [CVE-2016-0798] In the BN_hex2bn function, the number of hex digits is calculated using an int value |i|. Later |bn_expand| is called with a value of |i * 4|. For large values of |i| this can result in |bn_expand| not allocating any memory because |i * 4| is negative. This can leave the internal BIGNUM data field as NULL leading to a subsequent NULL pointer dereference. For very large values of |i|, the calculation |i * 4| could be a positive value smaller than |i|. In this case memory is allocated to the internal BIGNUM data field, but it is insufficiently sized leading to heap corruption. A similar issue exists in BN_dec2bn. This could have security consequences if BN_hex2bn/BN_dec2bn is ever called by user applications with very large untrusted hex/dec data. This is anticipated to be a rare occurrence. [CVE-2016-0797] The internal |fmtstr| function used in processing a "%s" formatted string in the BIO_*printf functions could overflow while calculating the length of a string and cause an out-of-bounds read when printing very long strings. [CVE-2016-0799] A side-channel attack was found which makes use of cache-bank conflicts on the Intel Sandy-Bridge microarchitecture which could lead to the recovery of RSA keys. [CVE-2016-0702] s2_srvr.c did not enforce that clear-key-length is 0 for non-export ciphers. If clear-key bytes are present for these ciphers, they displace encrypted-key bytes. [CVE-2016-0703] s2_srvr.c overwrites the wrong bytes in the master key when applying Bleichenbacher protection for export cipher suites. [CVE-2016-0704] III. Impact Servers that have SSLv2 protocol enabled are vulnerable to the "DROWN" attack which allows a remote attacker to fast attack many recorded TLS connections made to the server, even when the client did not make any SSLv2 connections themselves. An attacker who can supply malformed DSA private keys to OpenSSL applications may be able to cause memory corruption which would lead to a Denial of Service condition. [CVE-2016-0705] An attacker connecting with an invalid username can cause memory leak, which could eventually lead to a Denial of Service condition. [CVE-2016-0798] An attacker who can inject malformed data into an application may be able to cause memory corruption which would lead to a Denial of Service condition. [CVE-2016-0797, CVE-2016-0799] A local attacker who has control of code in a thread running on the same hyper-threaded core as the victim thread which is performing decryptions could recover RSA keys. [CVE-2016-0702] An eavesdropper who can intercept SSLv2 handshake can conduct an efficient divide-and-conquer key recovery attack and use the server as an oracle to determine the SSLv2 master-key, using only 16 connections to the server and negligible computation. [CVE-2016-0703] An attacker can use the Bleichenbacher oracle, which enables more efficient variant of the DROWN attack. [CVE-2016-0704] IV. Workaround No workaround is available. V. Solution Perform one of the following: 1) Upgrade your vulnerable system to a supported FreeBSD stable or release / security branch (releng) dated after the correction date. Restart all deamons using the library, or reboot the system. 2) To update your vulnerable system via a binary patch: Systems running a RELEASE version of FreeBSD on the i386 or amd64 platforms can be updated via the freebsd-update(8) utility: # freebsd-update fetch # freebsd-update install Restart all deamons using the library, or reboot the system. 3) To update your vulnerable system via a source code patch: The following patches have been verified to apply to the applicable FreeBSD release branches. a) Download the relevant patch from the location below, and verify the detached PGP signature using your PGP utility. [FreeBSD 9.3] # fetch https://security.FreeBSD.org/patches/SA-16:12/openssl-9.3.patch.xz # fetch https://security.FreeBSD.org/patches/SA-16:12/openssl-9.3.patch.xz.asc # gpg --verify openssl-9.3.patch.xz.asc Note that the initial patch version contains a serious regression that would lead to crash. The following patch must be applied to address it. # fetch https://security.FreeBSD.org/patches/SA-16:12/openssl-9.3-fix.patch # fetch https://security.FreeBSD.org/patches/SA-16:12/openssl-9.3-fix.patch.asc # gpg --verify openssl-9.3-fix.patch.asc [FreeBSD 10.1] # fetch https://security.FreeBSD.org/patches/SA-16:12/openssl-10.1.patch.xz # fetch https://security.FreeBSD.org/patches/SA-16:12/openssl-10.1.patch.xz.asc # gpg --verify openssl-10.1.patch.xz.asc [FreeBSD 10.2] # fetch https://security.FreeBSD.org/patches/SA-16:12/openssl-10.2.patch # fetch https://security.FreeBSD.org/patches/SA-16:12/openssl-10.2.patch.asc # gpg --verify openssl-10.2.patch.asc b) Apply the patch. Execute the following commands as root: # cd /usr/src # patch < /path/to/patch c) Recompile the operating system using buildworld and installworld as described in . Restart all deamons using the library, or reboot the system. VI. Correction details The following list contains the correction revision numbers for each affected branch. Branch/path Revision - ------------------------------------------------------------------------- stable/9/ r296598 releng/9.3/ r296611 stable/10/ r296371 releng/10.1/ r296341 releng/10.2/ r296341 - ------------------------------------------------------------------------- To see which files were modified by a particular revision, run the following command, replacing NNNNNN with the revision number, on a machine with Subversion installed: # svn diff -cNNNNNN --summarize svn://svn.freebsd.org/base Or visit the following URL, replacing NNNNNN with the revision number: VII. References The latest revision of this advisory is available at -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.1.11 (FreeBSD) iQIcBAEBCgAGBQJW4UchAAoJEO1n7NZdz2rnNC8P/2YSnc2DaOH37BZXKBKCt2iv rzTlQ6Cdr2n3r0k6Ayp1MonEfndWl9d86us6Z5ssfMrNsmJGWZv3Yj1Y8H12HE8+ ZhHCJ44ZYbyaDSe/vigG1S+xYILKP6uOxJYPWH5lXD9Yr20dHIJ8s3e9Jsai8aY2 aXMSVz67t84QJUoxAf5yEDsmY2drA5myppkRCRB1Xcb3qVebgwwQ4XkB+rJjjNjg rG0DFbTxLnStr/geEDC+WdeAzLH6D035gFRkHL6uIOfOX8UcYNnf4pVXUgymWJzI E/su+Cij/ckhV6UuOyNvKgN8uEs5XCny/10LKHqpPDhcYY6L8Dg47rI+2acOdFUi 5+79rx7+gUs71zC4D6hFCldUqOVpNYDRBYhX+MNqYkLn5XYEffbckv5zSkg53+aE Rf1G90VcC+yHRFu2hgCTOGXsayOAJhvCRTnuqLncKpznFSRD+1a3XUm2zS79gfpN f/uYIYmPbE1/uCU4StAlemdiH5vhYoWsP8tkBJsL8s6jMbV1REqukPJUPdDSaJmj rHLvige7yr1QTWYBQ1ghRXJml+3xDSst/RZzqn+QelsDoUwa1wJa6kc5Ki74eXmi XyuklOME8cbfUc8TPLqv4Lqbvr0nGK71jT0M7zG+eQTJsUls5EFBPhWL/6+SU29I Lb+5Q4Wn9Qlmxfj0Nm3U =f6Cw -----END PGP SIGNATURE-----