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Category:   Application (VPN)  >   OpenSSL Vendors:
(FreeBSD Issues Fix) OpenSSL DTLS Retransmission Error May Let Remote Users Deny Service
SecurityTracker Alert ID:  1029627
SecurityTracker URL:
CVE Reference:   CVE-2013-6450   (Links to External Site)
Date:  Jan 15 2014
Impact:   Denial of service via network
Fix Available:  Yes  Vendor Confirmed:  Yes  
Version(s): 1.0 - 1.0.1e
Description:   A vulnerability was reported in OpenSSL. A remote user can cause denial of service conditions.

The DTLS retransmission implementation does not properly maintain data structures for digest and encryption contexts. A remote user conducting a man-in-the-middle attack or a remote server may be able to trigger the use of a different context and cause the target client to crash.

Dmitry Sobinov reported this vulnerability.

Impact:   A remote user may be able to conduct man-in-the-middle attacks to deny service.
Solution:   FreeBSD has issued a fix.

The FreeBSD advisory is available at:

Vendor URL: (Links to External Site)
Cause:   State error
Underlying OS:  UNIX (FreeBSD)
Underlying OS Comments:  10.0-PRERELEASE

Message History:   This archive entry is a follow-up to the message listed below.
Jan 1 2014 OpenSSL DTLS Retransmission Error May Let Remote Users Deny Service

 Source Message Contents

Subject:  FreeBSD Security Advisory FreeBSD-SA-14:03.openssl

Hash: SHA512

FreeBSD-SA-14:03.openssl                                    Security Advisory
                                                          The FreeBSD Project

Topic:          OpenSSL multiple vulnerabilities

Category:       contrib
Module:         openssl
Announced:      2014-01-14
Affects:        FreeBSD 10.0 prior to 10.0-RC5
Corrected:      2014-01-07 20:04:41 UTC (stable/10, 10.0-PRERELEASE)
                2014-01-07 20:06:20 UTC (releng/10.0, 10.0-RC5)
                2014-01-07 20:06:20 UTC (releng/10.0, 10.0-RC4-p1)
                2014-01-07 20:06:20 UTC (releng/10.0, 10.0-RC3-p1)
                2014-01-07 20:06:20 UTC (releng/10.0, 10.0-RC2-p1)
                2014-01-07 20:06:20 UTC (releng/10.0, 10.0-RC1-p1)
CVE Name:       CVE-2013-4353, CVE-2013-6449, CVE-2013-6450

For general information regarding FreeBSD Security Advisories,
including descriptions of the fields above, security branches, and the
following sections, please visit <URL:>.

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 carefully crafted invalid TLS handshake could crash OpenSSL with a NULL
pointer exception. [CVE-2013-4353]

A flaw in DTLS handling can cause an application using OpenSSL and DTLS to
crash. [CVE-2013-6450]

A flaw in OpenSSL can cause an application using OpenSSL to crash when using
TLS version 1.2. [CVE-2013-6449]

III. Impact

An attacker can send a specifically crafted packet that could cause an OpenSSL
enabled application to crash, resulting in a Denial of Service.

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.

2) 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.

# fetch
# fetch
# gpg --verify openssl.patch.asc

b) Execute the following commands as root:

# cd /usr/src
# patch < /path/to/patch

Recompile the operating system using buildworld and installworld as
described in <URL:>.

Restart all deamons using the library, or reboot the system.

3) 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

VI.  Correction details

The following list contains the correction revision numbers for each
affected branch.

Branch/path                                                      Revision
- -------------------------------------------------------------------------
stable/10/                                                        r260404
releng/10.0/                                                      r260405
- -------------------------------------------------------------------------

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://

Or visit the following URL, replacing NNNNNN with the revision number:


VII. References


The latest revision of this advisory is available at

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