SSH Communications Security 
   Helsinki, Finland - October 1, 2003

SSH Secure Shell Security Vulnerability in BER Decoding

Description

   A vulnerability has been detected in the way Secure Shell handles the decoding of BER/DER
   encoded packets. BER/DER encoding is applied in digital certificates, which are used for
   authenticating a user to a host. Certificates are also commonly used for authenticating
   SSL/TLS connections.
   Using malformed BER/DER packets, the receiving host can potentially crash making a
   Denial-of-Service (DoS) attack possible.
   Please note that this vulnerability does not apply for users of non-commercial versions of
   SSH Secure Shell (Unix), since the non-commercial versions do not contain ASN.1 related
   libraries.

Affected Products

   You are vulnerable if:
     * You are using certificate based authentication in commercially available versions of SSH
       Secure Shell with the "Pki" definition in the configuration file. This applies to Windows
       and Unix Secure Shell Servers.
     * You are using hostbased authentication for the server and the client. It is not possible
       to disable certificate authentication in hostbased configurations.
     * You are using the commercial or non-commercial version of the SSH Secure Shell Client for
       Windows.

   Your server is not vulnerable if:
     * You are using password authentication only
     * You use the non-commercial Unix distribution that does not contain the PKI functionality.
     * You allow public key authentication WITHOUT specifying the "Pki" keyword in the server
       configuration file (sshd2_config).

Action

   We strongly advise you to upgrade your installation to the 3.2.9 version of SSH Secure Shell
   as soon as possible.
   Customers may download the SSH Secure Shell update from the Updates and Packages at Download
   Section. A valid license file is required for all the binaries. Depending on your license
   file the Unix binaries will function as SSH Secure Shell for Workstations or SSH Secure Shell
   for Servers product. If you wish to obtain a license file, please visit our online store or
   contact your sales representative.
   Updating SSH Secure Shell from 3.1.x to 3.2.5
   If you have a commercial license for 3.1.x or 3.2.x versions, you can install the 3.2.9
   version binaries on top of the old 3.1.x or 3.2.x ones.
   Updates and Packages
   SSH Secure Shell for Workstations 3.2
   SSH Secure Shell for Servers 3.2
   SSH Secure Shell for Windows Servers 3.2

Versions

   All versions from version 3.0 to 3.2.5 are affected.

SSH Communications Security is committed to utmost security

   SSH Communications Security apologizes for any inconvenience caused. We take security of the
   systems of our customers very seriously and do our utmost to provide secure software. We
   strongly urge all customers to consider the implications of this vulnerability and to make an
   educated decision on whether or not to update/upgrade.