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Category:   Application (Security)  >   OpenSSL Vendors:   OpenSSL.org
(Conectiva Issues Fix) OpenSSL Uses Potentially Predictable Pseudo-Random Number Generator
SecurityTracker Alert ID:  1002369
SecurityTracker URL:  http://securitytracker.com/id/1002369
CVE Reference:   GENERIC-MAP-NOMATCH   (Links to External Site)
Date:  Sep 8 2001
Impact:   Disclosure of authentication information
Fix Available:  Yes  Vendor Confirmed:  Yes  
Version(s): up to 0.9.6a
Description:   OpenSSL announced a vulnerability in the cryptographic toolkit's pseudo-random number generator (PRNG) that could allow an attacker to predict future PRNG output.

The pseudo-random number generator (PRNG) in SSLeay/OpenSSL reportedly contains a design error that weakens the function such that it could become predictable.

The PRNG function (source code file crypto/md_rand.c) uses a hash function to update its internal secret state and to generate output. The secret state consists of two items: 1) a chaining variable message digest 'md' that is the output of the hash function, and 2) a large buffer variable 'state' that is is accessed circularly and used for storing additional entropy.

When generating output bytes, vulnerable versions of OpenSSL set the 'md' variable to the hash of one half of its previous value (which is also the same half that was used as PRNG output, meaning that it is not a secret value) and some other data, including bytes from 'state'. In addition, the number of bytes used from 'state' depended on the number of bytes requested as PRNG output and could be as small as one, making a brute-force analysis of all possible cases feasible.

These two design flaws make it possible to reconstruct the complete internal PRNG state from the output of one large PRNG request (large enough gain knowledge on the 'md' variable) followed by enough consecutive 1-byte PRNG requests to cycle through all of 'state'.

Impact:   A user could potentially determine future PRNG output, which could lead to an attack of the system using the PRNG output.
Solution:   The vendor has released a fix. See the Source Message for the vendor's advisory containing directions on how to obtain the appropriate fix.
Vendor URL:  www.openssl.org/ (Links to External Site)
Cause:   Randomization error
Underlying OS:   Linux (Conectiva)

Message History:   This archive entry is a follow-up to the message listed below.
Jul 10 2001 OpenSSL Uses Potentially Predictable Pseudo-Random Number Generator


 Source Message Contents
Date:  Thu, 30 Aug 2001 16:11:54 -0300
Subject:  [conectiva-updates] [CLA-2001:418] Conectiva Linux Security Announcement - openssl


-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

- --------------------------------------------------------------------------
CONECTIVA LINUX SECURITY ANNOUNCEMENT 
- --------------------------------------------------------------------------

PACKAGE   : openssl
SUMMARY   : Several vulnerabilities in the OpenSSL library
DATE      : 2001-08-30 16:11:00
ID        : CLA-2001:418
RELEVANT
RELEASES  : 4.0, 4.0es, 4.1, 4.2, 5.0, prg graficos, ecommerce, 5.1, 6.0, 7.0

- -------------------------------------------------------------------------

DESCRIPTION
 OpenSSL is a library providing several crypto and digital certificate
 handling functions.
 Several vulnerabilities have been addressed in newer versions of this
 library:
 1. OpenSSL now avoids using environment variables when running as
 root;
 2. The result of RSA-CRT is now checked to reduce the possibility of
 deducing the private key from an incorrectly calculated signature;
 3. Changes to prevent Bleichenbacher's DSA attack;
 4. OpenSSL now zeroes the premaster secret after deriving the master
 secret in DH ciphersuites;
 5. Fix for a vulnerability in the pseudo random number generator
 which allowed an attacker to predict the internal state of the PRNG
 and thus predict future PRNG output.
 The first four vulnerabilities have been addressed in the 0.9.6a
 version of the library and affect Conectiva Linux <= 6.0 only, while
 the last one was fixed with the 0.9.6b release and affects Conectiva
 Linux 7.0 and earlier.
 The packages available through this update have been patched to fix
 all these vulnerabilities. Thanks to the OpenSSL team for releasing
 the new versions and to Nalin Dahyabhai from Redhat for providing
 patches for older versions.


SOLUTION
 All users should upgrade the OpenSSL library. After the update,
 programs which use the library, such as apache and openssh, should be
 restarted.
 
 IMPORTANT: updated packages for Conectiva Linux 4.0 and 4.0es are not
 yet available.
 
 
 REFERENCES
 1. http://www.securityfocus.com/bid/3004
 2. http://www.openssl.org
 3.http://marc.theaimsgroup.com/?l=openssl-announce&m=98655255404174&w=2


DIRECT DOWNLOAD LINKS TO THE UPDATED PACKAGES
ftp://atualizacoes.conectiva.com.br/4.1/SRPMS/openssl-0.9.5a-2U41_1cl.src.rpm
ftp://atualizacoes.conectiva.com.br/4.1/i386/openssl-devel-0.9.5a-2U41_1cl.i386.rpm
ftp://atualizacoes.conectiva.com.br/4.1/i386/openssl-0.9.5a-2U41_1cl.i386.rpm
ftp://atualizacoes.conectiva.com.br/4.2/SRPMS/openssl-0.9.5a-2U42_1cl.src.rpm
ftp://atualizacoes.conectiva.com.br/4.2/i386/openssl-devel-0.9.5a-2U42_1cl.i386.rpm
ftp://atualizacoes.conectiva.com.br/4.2/i386/openssl-0.9.5a-2U42_1cl.i386.rpm
ftp://atualizacoes.conectiva.com.br/5.0/SRPMS/openssl-0.9.5a-2U50_1cl.src.rpm
ftp://atualizacoes.conectiva.com.br/5.0/i386/openssl-devel-0.9.5a-2U50_1cl.i386.rpm
ftp://atualizacoes.conectiva.com.br/5.0/i386/openssl-0.9.5a-2U50_1cl.i386.rpm
ftp://atualizacoes.conectiva.com.br/5.1/SRPMS/openssl-0.9.5a-2U51_1cl.src.rpm
ftp://atualizacoes.conectiva.com.br/5.1/i386/openssl-0.9.5a-2U51_1cl.i386.rpm
ftp://atualizacoes.conectiva.com.br/5.1/i386/openssl-devel-0.9.5a-2U51_1cl.i386.rpm
ftp://atualizacoes.conectiva.com.br/6.0/SRPMS/openssl-0.9.6-4U60_1cl.src.rpm
ftp://atualizacoes.conectiva.com.br/6.0/RPMS/openssl-0.9.6-4U60_1cl.i386.rpm
ftp://atualizacoes.conectiva.com.br/6.0/RPMS/openssl-devel-0.9.6-4U60_1cl.i386.rpm
ftp://atualizacoes.conectiva.com.br/7.0/SRPMS/openssl-0.9.6a-3U70_1cl.src.rpm
ftp://atualizacoes.conectiva.com.br/7.0/RPMS/openssl-doc-0.9.6a-3U70_1cl.i386.rpm
ftp://atualizacoes.conectiva.com.br/7.0/RPMS/openssl-devel-0.9.6a-3U70_1cl.i386.rpm
ftp://atualizacoes.conectiva.com.br/7.0/RPMS/openssl-0.9.6a-3U70_1cl.i386.rpm
ftp://atualizacoes.conectiva.com.br/7.0/RPMS/openssl-devel-static-0.9.6a-3U70_1cl.i386.rpm
ftp://atualizacoes.conectiva.com.br/7.0/RPMS/openssl-progs-0.9.6a-3U70_1cl.i386.rpm
ftp://atualizacoes.conectiva.com.br/ferramentas/ecommerce/SRPMS/openssl-0.9.5a-2U50_1cl.src.rpm
ftp://atualizacoes.conectiva.com.br/ferramentas/ecommerce/i386/openssl-devel-0.9.5a-2U50_1cl.i386.rpm
ftp://atualizacoes.conectiva.com.br/ferramentas/ecommerce/i386/openssl-0.9.5a-2U50_1cl.i386.rpm
ftp://atualizacoes.conectiva.com.br/ferramentas/graficas/SRPMS/openssl-0.9.5a-2U50_1cl.src.rpm
ftp://atualizacoes.conectiva.com.br/ferramentas/graficas/i386/openssl-devel-0.9.5a-2U50_1cl.i386.rpm
ftp://atualizacoes.conectiva.com.br/ferramentas/graficas/i386/openssl-0.9.5a-2U50_1cl.i386.rpm


ADDITIONAL INSTRUCTIONS
 Users of Conectiva Linux version 6.0 or higher may use apt to perform 
 upgrades of RPM packages:
 - add the following line to /etc/apt/sources.list if it is not there yet
   (you may also use linuxconf to do this):

 rpm [cncbr] ftp://atualizacoes.conectiva.com.br 6.0/conectiva updates

(replace 6.0 with the correct version number if you are not running CL6.0)

 - run:                 apt-get update
 - after that, execute: apt-get upgrade

 Detailed instructions reagarding the use of apt and upgrade examples 
 can be found at http://distro.conectiva.com.br/atualizacoes/#apt?idioma=en


- -------------------------------------------------------------------------
All packages are signed with Conectiva's GPG key. The key and instructions
on how to import it can be found at 
http://distro.conectiva.com.br/seguranca/chave/?idioma=en
Instructions on how to check the signatures of the RPM packages can be
found at http://distro.conectiva.com.br/seguranca/politica/?idioma=en
- -------------------------------------------------------------------------
All our advisories and generic update instructions can be viewed at
http://distro.conectiva.com.br/atualizacoes/?idioma=en

- -------------------------------------------------------------------------
subscribe: conectiva-updates-subscribe@papaleguas.conectiva.com.br
unsubscribe: conectiva-updates-unsubscribe@papaleguas.conectiva.com.br
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Version: GnuPG v1.0.6 (GNU/Linux)
Comment: For info see http://www.gnupg.org

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