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Home » Hacking News » NetBSD 2003-007: encryption weakness in OpenSSL

NetBSD 2003-007: encryption weakness in OpenSSL

by Nikola Strahija on March 26th, 2003 Czech cryptologists Vlastimil Klima, Ondrej Pokorny, and Tomas Rosa have come up with an extension of the "Bleichenbacher attack". This attack allows an attacker to perform a single RSA private key operation on a ciphertext of its choice using the server's RSA key.


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NetBSD Security Advisory 2003-007
=================================

Topic: (Another) Encryption weakness in OpenSSL code

Version: NetBSD-current: source prior to March 21, 2003
NetBSD-1.6.1: not affected
NetBSD-1.6: affected
NetBSD-1.5.3: affected
NetBSD-1.5.2: affected
NetBSD-1.5.1: affected
NetBSD-1.5: affected
NetBSD-1.4*: not affected
pkgsrc: prior to openssl-0.9.6gnb2

Severity: Attacker can perform crypto operations using server's private
keys.

Fixed: NetBSD-current: March 21, 2003
NetBSD-1.6 branch: March 21, 2003
NetBSD-1.5 branch: March 21, 2003
pkgsrc: openssl-0.9.6gnb2


Abstract
========

Quote from bugtraq posting:

Czech cryptologists Vlastimil Klima, Ondrej Pokorny, and Tomas Rosa
have come up with an extension of the "Bleichenbacher attack" on RSA
with PKCS #1 v1.5 padding as used in SSL 3.0 and TLS 1.0. Their
attack requires the attacker to open millions of SSL/TLS connections
to the server under attack; the server's behaviour when faced with
specially made-up RSA ciphertexts can reveal information that in
effect allows the attacker to perform a single RSA private key
operation on a ciphertext of its choice using the server's RSA key.
Note that the server's RSA key is not compromised in this attack.

No services using SSL/TLS are enabled by default in NetBSD, however, by
enabling services built with these libraries, a system could become
vulnerable to the compromise.

NOTE: Two OpenSSL advisories have appeared within 2 days of each other.
while the patches affect libssl in this SA, and libcrypto in
2003-005, please be aware that there are two separate issues
with separate sets of patches.


Technical Details
=================

http://marc.theaimsgroup.com/?l=bugtraq&m=104811162730834&w=2


Solutions and Workarounds
=========================

The following instructions describe how to upgrade your libssl
binaries by updating your source tree and rebuilding and installing
a new version of libssl.

Be sure to restart running instances of programs that use the libssl
library after upgrading.

If you have any statically-linked binaries that linked against a
vulnerable libssl, you need to recompile them.


* NetBSD-current:

Systems running NetBSD-current dated from before 2003-02-21
should be upgraded to NetBSD-current dated 2003-02-21 or later.

The following file needs to be updated from the
netbsd-current CVS branch (aka HEAD):
crypto/dist/openssl/ssl/s3_srvr.c

To update from CVS, re-build, and re-install libssl:
# cd src
# cvs update -d -P crypto/dist/openssl/ssl/s3_srvr.c
# cd lib/libssl
# make USETOOLS=no cleandir dependall
# make USETOOLS=no install


* NetBSD 1.6:

The binary distribution of NetBSD 1.6 is vulnerable.

If a source-based point upgrade is required, sources from the
NetBSD 1.6 branch dated 2003-03-21 or later should be used.

The following file needs to be updated from the
netbsd-1-6 CVS branch:
crypto/dist/openssl/ssl/s3_srvr.c

To update from CVS, re-build, and re-install libssl:
# cd src
# cvs update -d -P -r netbsd-1-6 crypto/dist/openssl/ssl/s3_srvr.c
# cd lib/libssl
# make USETOOLS=no cleandir dependall
# make USETOOLS=no install


* NetBSD 1.5, 1.5.1, 1.5.2, 1.5.3:

The binary distribution of NetBSD 1.5.3 is vulnerable.

Systems running NetBSD-1.5.x dated from before 2003-03-20
should be upgraded to NetBSD-1.5 branch dated 2003-03-21 or later.

The following file needs to be updated from the
netbsd-1-5 CVS branch:
crypto/dist/openssl/ssl/s3_srvr.c

To update from CVS, re-build, and re-install libssl:
# cd src
# cvs update -d -P -r netbsd-1-5 crypto/dist/openssl/ssl/s3_srvr.c
# cd lib/libssl
# make cleandir dependall
# make install


* NetBSD 1.4, 1.4.1, 1.4.2, 1.4.3:

OpenSSL was not included in the base system in NetBSD-1.4.*
Follow the directions for pkgsrc if you have installed it from
pkgsrc.


* pkgsrc:

openssl (pkgsrc/security/openssl) prior to openssl-0.9.6gnb2 are
vulnerable. Upgrade to openssl-0.9.6gnb2 or later.

Packages which require openssl can be found by running 'pkg_info
openssl'. Depending on the method you choose to update pkgsrc
packages, a rebuild of the packages on that list may be
performed for you by the package system. If you update using the
experimental 'make replace' target, you will need to manually
update any packages which build static binaries with libssl.a.

If you have statically linked binaries in pkgsrc, they have to be
rebuilt. Statically linked binaries can be identified by the
following command (note: be sure to include the directory you install
pkgsrc binaries to, if you've changed LOCALBASE from the default of
/usr/pkg)

file /usr/pkg/{bin,sbin,libexec}/* | grep static


Thanks To
=========

Bugtraq and the OpenSSL team.


Revision History
================

2003-03-26 Initial release

More Information
================

An up-to-date PGP signed copy of this release will be maintained at
ftp://ftp.netbsd.org/pub/NetBSD/security/advisories/NetBSD-SA2003-007.txt.asc

Information about NetBSD and NetBSD security can be found at
http://www.NetBSD.ORG/ and http://www.NetBSD.ORG/Security/.


Copyright 2003, The NetBSD Foundation, Inc. All Rights Reserved.

$NetBSD: NetBSD-SA2003-007.txt,v 1.5 2003/03/26 05:51:26 david Exp $

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