CVE Name:       CAN-2004-0079
FreeBSD only:   NO

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

I.   Background

FreeBSD includes software from the OpenSSL Project.  The OpenSSL
Project is a collaborative effort to develop a robust, commercial-
grade, full-featured, and 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

When processing an SSL/TLS ChangeCipherSpec message, OpenSSL may fail to
check that a new cipher has been previously negotiated.  This may result
in a null pointer dereference.

III. Impact

A remote attacker could perform a specially crafted SSL/TLS handshake
with an application that utilizes OpenSSL, triggering the null pointer
dereference and causing the application to crash.  Depending upon the
specifics of the application, this may result in an effective
denial-of-service.

IV.  Workaround

No workaround is known.

V.   Solution

Perform one of the following:

1) Upgrade your vulnerable system to 4-STABLE; or to the RELENG_5_2,
RELENG_4_9, or RELENG_4_8 security branch dated after the correction
date.

2) To patch your present system:

The following patches have been verified to apply to FreeBSD 4.8,
4.9, 5.1, and 5.2 systems.

a) Download the relevant patch from the location below, and verify the
detached PGP signature using your PGP utility.

# fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-04:05/openssl.patch
# fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-04:05/openssl.patch.asc

b) Execute the following commands as root:

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

c) Recompile the operating system as described in
<URL: http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/makeworld.html >.

Note that any statically linked applications that are not part of the
base system (i.e. from the Ports Collection or other 3rd-party sources)
must be recompiled.

All affected applications must be restarted for them to use the
corrected library.  Though not required, rebooting may be the easiest
way to accomplish this.

VI.  Correction details

The following list contains the revision numbers of each file that was
corrected in FreeBSD.

Branch                                                                                    Revision
           Path
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VII. References

<URL: http://www.openssl.org/news/secadv_20040317.txt >
<URL: http://cvs.openssl.org/chngview?cn=12033 >