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Home » Hacking News » SuSE Security Announcement: openssl (SuSE-SA:2003:011)

SuSE Security Announcement: openssl (SuSE-SA:2003:011)

by Nikola Strahija on February 26th, 2003 A security weakness has been found, known as "Vaudenay timing attack on CBC", named after one of the discoverers (Brice Canvel (EPFL), Alain Hiltgen (UBS), Serge Vaudenay (EPFL), and Martin Vuagnoux (EPFL, Ilion)). The weakness may allow an attacker to obtain a plaintext data block by observing timing differences in response to two different error cases (cipher padding errors vs. MAC verification errors).


Package: openssl
Announcement-ID: SuSE-SA:2003:011
Date: Wednesday, Feb. 26th 2003 15:20 MET
Affected products: 7.1, 7.2, 7.3, 8.0, 8.1
SuSE Linux Database Server,
SuSE eMail Server III, 3.1
SuSE Linux Enterprise Server 7
SuSE Linux Enterprise Server 8
SuSE Linux Firewall on CD/Admin host
SuSE Linux Connectivity Server
SuSE Linux Office Server
Vulnerability Type: remote attack on encryption
Severity (1-10): 5
SuSE default package: yes
Cross References: CAN-2003-0078

Content of this advisory:
1) security vulnerability resolved: openssl
problem description, discussion, solution and upgrade information
2) pending vulnerabilities, solutions, workarounds:
- vnc
- w3m
3) standard appendix (further information)

______________________________________________________________________________

1) problem description, brief discussion, solution, upgrade information

OpenSSL is an implementation of the Secure Sockets Layer and Transport
Layer Security protocols and provides strong cryptography for many
applications in a Linux system. It is a default package in all SuSE
products.

A security weakness has been found, known as "Vaudenay timing attack
on CBC", named after one of the discoverers (Brice Canvel (EPFL), Alain
Hiltgen (UBS), Serge Vaudenay (EPFL), and Martin Vuagnoux (EPFL, Ilion)).
The weakness may allow an attacker to obtain a plaintext data block by
observing timing differences in response to two different error cases
(cipher padding errors vs. MAC verification errors).
In order to exploit this vulnerability, the attacker has to meet certain
requirements: The network connection between client and server must be
of high quality to be able to observe timing differences, the attacker
must be able to perform a man-in-the-middle attack, the transactions
must repeatedly contain the same (encrypted) plain text block (such as
a pop password or alike), and decoding failures in the SSL layer must
not be propagated to the application that is using the SSL connection.
These exploitation conditions considerably reduce the security risk
imposed by the vulnerability. However, we recommend to completely
remedy this weakness by installing the update packages for your system
according to the following guidelines. There does not exist any temporary
workaround for this problem other than applying the update packages.


Please download the update package for your distribution and verify its
integrity by the methods listed in section 3) of this announcement.
Our maintenance customers are being notified individually. The packages
are being offered to install from the maintenance web.

SPECIAL INSTALLATION INSTRUCTIONS:
====================================
Please update your openssl package using the command
rpm -Fhv
The operation of this command must not be interrupted! An interrupted
update of the openssl package may cause large protions of your system to
fail.
After performing the update, it is adviseable to run the command
"ldconfig" to update the shared library loading cache.
After the update, running processes in your system will continue to
use the shared libraries from the old package before the update.
Generally, it is necessary to restart all of these processes to
completely fix the vulnerability in your system. The command
lsof -n 2>/dev/null | grep RPMDELETE
can be used to find the binaries and processes that still use the old
shared libraries. In all cases, the next reboot of the system will cause
the old shared libraries to be completely removed from the system.
Alternatively, a transition to runlevel 1 (single user mode) and back
to the default runlevel will have the same effect.



Intel i386 Platform:

SuSE-8.1:
ftp://ftp.suse.com/pub/suse/i386/update/8.1/rpm/i586/openssl-0.9.6g-55.i586.rpm
7fbf4d975180a20ff8dedc8adbdecc59
patch rpm(s):
ftp://ftp.suse.com/pub/suse/i386/update/8.1/rpm/i586/openssl-0.9.6g-55.i586.patch.rpm
6ed4321ec536aa718189702470c33091
source rpm(s):
ftp://ftp.suse.com/pub/suse/i386/update/8.1/rpm/src/openssl-0.9.6g-55.src.rpm
90fc753346dd2aff00eee4c530cea84a

SuSE-8.0:
ftp://ftp.suse.com/pub/suse/i386/update/8.0/sec1/openssl-0.9.6c-83.i386.rpm
d6246b820780993cc0e2b48597743a8f
patch rpm(s):
ftp://ftp.suse.com/pub/suse/i386/update/8.0/sec1/openssl-0.9.6c-83.i386.patch.rpm
2d933e913a9062de6a1fa35de969d211
source rpm(s):
ftp://ftp.suse.com/pub/suse/i386/update/8.0/zq1/openssl-0.9.6c-83.src.rpm
b4b887a7311e9734a14d11e1a380f76e

SuSE-7.3:
ftp://ftp.suse.com/pub/suse/i386/update/7.3/sec1/openssl-0.9.6b-154.i386.rpm
d3c0f892441c09c8c5a689e2af04ba55
source rpm(s):
ftp://ftp.suse.com/pub/suse/i386/update/7.3/zq1/openssl-0.9.6b-154.src.rpm
31ec962fe3549a713b9e6937190a88fb

SuSE-7.2:
ftp://ftp.suse.com/pub/suse/i386/update/7.2/sec1/openssl-0.9.6a-78.i386.rpm
d14f67c34c589f168b750b18c9162508
source rpm(s):
ftp://ftp.suse.com/pub/suse/i386/update/7.2/zq1/openssl-0.9.6a-78.src.rpm
2ba5a416d6ca3cb75c9aabb5a25bb532

SuSE-7.1:
ftp://ftp.suse.com/pub/suse/i386/update/7.1/sec1/openssl-0.9.6a-78.i386.rpm
c6b711573555982fadd31cfa179dd9dc
source rpm(s):
ftp://ftp.suse.com/pub/suse/i386/update/7.1/zq1/openssl-0.9.6a-78.src.rpm
d00df30aa6ec6a3872c58da709181879



Sparc Platform:

SuSE-7.3:
ftp://ftp.suse.com/pub/suse/sparc/update/7.3/sec1/openssl-0.9.6b-87.sparc.rpm
6a8f19a49a698b93e740121321f59e5d
source rpm(s):
ftp://ftp.suse.com/pub/suse/sparc/update/7.3/zq1/openssl-0.9.6b-87.src.rpm
50712c3fd35042278063622ad5cc77c7

AXP Alpha Platform:
The packages for the 7.1-axp distribution will be published soon.



PPC Power PC Platform:

SuSE-7.3:
ftp://ftp.suse.com/pub/suse/ppc/update/7.3/sec1/openssl-0.9.6b-147.ppc.rpm
051ef85d8e711819b2de38f55dc0023a
source rpm(s):
ftp://ftp.suse.com/pub/suse/ppc/update/7.3/zq1/openssl-0.9.6b-147.src.rpm
58631776b8fa88932eb57069a7f2878e

SuSE-7.1:
ftp://ftp.suse.com/pub/suse/ppc/update/7.1/sec1/openssl-0.9.6a-28.ppc.rpm
da5e7caa177316f3016dd98497e580de
source rpm(s):
ftp://ftp.suse.com/pub/suse/ppc/update/7.1/zq1/openssl-0.9.6a-28.src.rpm
b317144556c8f1890d15f304d95c5764



______________________________________________________________________________

2) Pending vulnerabilities in SuSE Distributions and Workarounds:

- vnc
VNC (Virtual Network Computing) uses a weak cookie generation process
which can be exploited by an attacker to bypass authentication.
New packages are currently being tested and will be available on our
FTP servers soon.

- w3m
The textbased web-browser w3m does not properly escape HTML tags.
A malicious HTML page or img alt attribute may lead to information
leakage. New packages will be available soon.
______________________________________________________________________________

3) standard appendix: authenticity verification, additional information

- Package authenticity verification:

SuSE update packages are available on many mirror ftp servers all over
the world. While this service is being considered valuable and important
to the free and open source software community, many users wish to be
sure about the origin of the package and its content before installing
the package. There are two verification methods that can be used
independently from each other to prove the authenticity of a downloaded
file or rpm package:
1) md5sums as provided in the (cryptographically signed) announcement.
2) using the internal gpg signatures of the rpm package.

1) execute the command
md5sum
after you downloaded the file from a SuSE ftp server or its mirrors.
Then, compare the resulting md5sum with the one that is listed in the
announcement. Since the announcement containing the checksums is
cryptographically signed (usually using the key [email protected]),
the checksums show proof of the authenticity of the package.
We disrecommend to subscribe to security lists which cause the
email message containing the announcement to be modified so that
the signature does not match after transport through the mailing
list software.
Downsides: You must be able to verify the authenticity of the
announcement in the first place. If RPM packages are being rebuilt
and a new version of a package is published on the ftp server, all
md5 sums for the files are useless.

2) rpm package signatures provide an easy way to verify the authenticity
of an rpm package. Use the command
rpm -v --checksig
to verify the signature of the package, where is the
filename of the rpm package that you have downloaded. Of course,
package authenticity verification can only target an un-installed rpm
package file.
Prerequisites:
a) gpg is installed
b) The package is signed using a certain key. The public part of this
key must be installed by the gpg program in the directory
~/.gnupg/ under the user's home directory who performs the
signature verification (usually root). You can import the key
that is used by SuSE in rpm packages for SuSE Linux by saving
this announcement to a file ("announcement.txt") and
running the command (do "su -" to be root):
gpg --batch; gpg < announcement.txt | gpg --import
SuSE Linux distributions version 7.1 and thereafter install the
key "[email protected]" upon installation or upgrade, provided that
the package gpg is installed. The file containing the public key
is placed at the top-level directory of the first CD (pubring.gpg)
and at ftp://ftp.suse.com/pub/suse/pubring.gpg-build.suse.de .


- SuSE runs two security mailing lists to which any interested party may
subscribe:

[email protected]
- general/linux/SuSE security discussion.
All SuSE security announcements are sent to this list.
To subscribe, send an email to
.

[email protected]
- SuSE's announce-only mailing list.
Only SuSE's security announcements are sent to this list.
To subscribe, send an email to
.

For general information or the frequently asked questions (faq)
send mail to:
or
respectively.

=====================================================================
SuSE's security contact is or .
The public key is listed below.
=====================================================================
______________________________________________________________________________

The information in this advisory may be distributed or reproduced,
provided that the advisory is not modified in any way. In particular,
it is desired that the clear-text signature shows proof of the
authenticity of the text.
SuSE Linux AG makes no warranties of any kind whatsoever with respect
to the information contained in this security advisory.


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