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Posted on 05 May 2016
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FreeBSD-SA-16:17.openssl Security Advisory
The FreeBSD Project
Topic: Multiple OpenSSL vulnerabilities
Category: contrib
Module: openssl
Announced: 2016-05-04
Credits: OpenSSL Project
Affects: All supported versions of FreeBSD.
Corrected: 2016-05-03 18:54:20 UTC (stable/10, 10.3-STABLE)
2016-05-04 15:25:47 UTC (releng/10.3, 10.3-RELEASE-p2)
2016-05-04 15:26:23 UTC (releng/10.2, 10.2-RELEASE-p16)
2016-05-04 15:27:09 UTC (releng/10.1, 10.1-RELEASE-p33)
2016-05-04 06:53:02 UTC (stable/9, 9.3-STABLE)
2016-05-04 15:27:09 UTC (releng/9.3, 9.3-RELEASE-p41)
CVE Name: CVE-2016-2105, CVE-2016-2106, CVE-2016-2107, CVE-2016-2109,
CVE-2016-2176
For general information regarding FreeBSD Security Advisories,
including descriptions of the fields above, security branches, and the
following sections, please visit <URL:https://security.FreeBSD.org/>.
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
The padding check in AES-NI CBC MAC was rewritten to be in constant time
by making sure that always the same bytes are read and compared against
either the MAC or padding bytes. But it no longer checked that there was
enough data to have both the MAC and padding bytes. [CVE-2016-2107]
An overflow can occur in the EVP_EncodeUpdate() function which is used for
Base64 encoding of binary data. [CVE-2016-2105]
An overflow can occur in the EVP_EncryptUpdate() function, however it is
believed that there can be no overflows in internal code due to this problem.
[CVE-2016-2106]
When ASN.1 data is read from a BIO using functions such as d2i_CMS_bio()
a short invalid encoding can casuse allocation of large amounts of memory
potentially consuming excessive resources or exhausting memory.
[CVE-2016-2109]
ASN1 Strings that are over 1024 bytes can cause an overread in applications
using the X509_NAME_oneline() function on EBCDIC systems. [CVE-2016-2176]
FreeBSD does not run on any EBCDIC systems and therefore is not affected.
III. Impact
A MITM attacker can use a padding oracle attack to decrypt traffic
when the connection uses an AES CBC cipher and the server support
AES-NI. [CVE-2016-2107]
If an attacker is able to supply very large amounts of input data then a
length check can overflow resulting in a heap corruption. [CVE-2016-2105]
Any application parsing untrusted data through d2i BIO functions are vulnerable
to memory exhaustion attack. [CVE-2016-2109] TLS applications are not affected.
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 daemons that use 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 daemons that use 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 10.x]
# fetch https://security.FreeBSD.org/patches/SA-16:17/openssl-10.patch
# fetch https://security.FreeBSD.org/patches/SA-16:17/openssl-10.patch.asc
# gpg --verify openssl-10.patch.asc
[FreeBSD 9.3]
# fetch https://security.FreeBSD.org/patches/SA-16:17/openssl-9.patc
# fetch https://security.FreeBSD.org/patches/SA-16:17/openssl-9.patch.asc
# gpg --verify openssl-9.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 <URL:https://www.FreeBSD.org/handbook/makeworld.html>.
Restart all daemons that use 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/ r299053
releng/9.3/ r299068
stable/10/ r298999
releng/10.1/ r299068
releng/10.2/ r299067
releng/10.3/ r299066
- -------------------------------------------------------------------------
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:
<URL:https://svnweb.freebsd.org/base?view=revision&revision=NNNNNN>
VII. References
<URL:https://www.openssl.org/news/secadv/20160503.txt>
<URL:https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2016-2105>
<URL:https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2016-2106>
<URL:https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2016-2107>
<URL:https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2016-2109>
<URL:https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2016-2176>
The latest revision of this advisory is available at
<URL:https://security.FreeBSD.org/advisories/FreeBSD-SA-16:17.openssl.asc>
