OPC UA User Authentication Token Exploit

OPC Foundation (OPCF) announced a new Security Bulletin (CVE-2018-7559) on April 12, 2018 concerning a potential security exploit in OPC UA servers:

"The vulnerability can allow a remote attacker to determine a Server's private key by sending carefully constructed bad UserIdentityTokens as part of an oracle attack."

Although the original issue was announced for .NET stack applications only, we discovered that it also affects the applications built with Prosys OPC UA Java SDK. Since this part of user authentication tokens are only handled on the SDK level, it does not concern the OPCF Java Stack.

Prosys OPC UA products affected

The vulnerability affects directly:

• All applications built with Prosys OPC UA Java SDK 3.1.2 and earlier
• Prosys OPC UA Simulation Server 3.0.0 and earlier
• Prosys OPC UA Modbus Server 1.2.2 and earlier

Fixed products

The issue is fixed in the Prosys OPC UA Java SDK 3.1.4, Simulation Server 3.1.4 and Modbus Server 1.2.4 and we encourage everyone to update to these versions.

Avoiding the issue in existing products

The issue can also be avoided by disabling the Security Policy Basic128Rsa15 in the server applications. So, if you are not able to update or you have known applications that enable user name authentication running at customer sites, we advice you to disable Basic128Rsa15 from those applications.

Basic128Rsa15 and Basic256 are deprecated from OPC UA 1.04, and we recommend using the Basic256Sha256 policy for older applications. OPC UA 1.04 defines new security policies, Aes128-Sha256-RsaOaep and Aes-256-Sha256-RsaPss, which replace the older policies. We are working on providing support for these policies in a future SDK version, which will be based on OPC UA 1.04.

More security information

You will find the currently announced security issues in Prosys OPC products from the blog under the Security tag.

You might also like to read about the OPC UA Security Process of the OPC Foundation.