Siemens Security Bulletin by Siemens ProductCERT

SSB-583110 © Siemens AG 2014 Page 1 of 2

SSB-583110: Customer Information about POODLE Attack on SSLv3 Protocol Vulnerabilities

Publication Date 2014-11-10 Last Update 2014-11-10 Current Version V1.0

Summary:

On October 15, 2014, a new attack on the encryption in SSLv3, called Padding Oracle On Downgraded Legacy Encryption (“POODLE”), was made public. The attack exploits a design vulnerability in the SSLv3 protocol, which is common to all software that uses SSLv3.

Siemens products also support this protocol and are therefore potentially vulnerable to this attack. However, an attacker would first have to compromise a user’s web browser (which is not a Siemens product). Then, if specific requirements are met, the vulnerability might allow an attacker to decrypt cipher text to obtain confidential information from data transferred over a network connection, leading to a potential compromise of Siemens industrial products.

Therefore, Siemens advises to deactivate SSLv3 in web browsers and use the recommended TLS protocol.

ATTACK REQUIREMENTS AND CRITICALITY

Only under certain circumstances an attack via POODLE may be successful (see figure above):

1. Both endpoint applications must be vulnerable to POODLE. So if either the client or the server application is not vulnerable to POODLE, the network connection is secure.

2. Web browsers must have an active web session on a server. The vulnerability is only exploitable when the web browser on the client accesses a server with an established active web session.

3. Attackers must be able to listen to and manipulate the network data that is exchanged between client and server.

4. Attackers must be able to manipulate the client, so that a high number of connections is established between client and server in a certain way. At the moment, only web browsers are known to be potentially exploitable.

This vulnerability was rated with low criticality: It has a CVSS score1 of 3.7 out of 10 (AV:N/AC:M/Au:N/C:P/I:N/A:N/E:POC/RL:W/RC:C).

1 The vulnerability classification has been performed by using the CVSSv2 scoring system.

Siemens Security Bulletin by Siemens ProductCERT

SSB-583110 © Siemens AG 2014 Page 2 of 2

COUNTER MEASURES

Siemens recommends the following measure for customers to mitigate the vulnerability:

Deactivate SSLv3 in web browsers and use the recommended TLS protocol. Deactivation of SSLv3 in the web browser is sufficient. Please refer to the documentation of the web browser on how to deactivate SSLv3.

In case SSLv3 cannot be deactivated on either client or server side:

Restrict use of SSLv3 connections to trusted networks.

Do not browse external sites while a web session to an SSLv3 capable device is active.

HISTORY DATA

V1.0 (2014-11-10): Publication Date

DISCLAIMER

See: http://www.siemens.com/terms_of_use