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OpenSSL Security Vulnerability (KEPServerEX 5.21 Release)

Last Update: 11/12/2018
Customers using the KEPServerEX OPC UA server or OPC UA Client driver should be aware of security vulnerabilities discovered in OpenSSL that impact KEPServerEX version 5.20.396 and earlier. Customers not using the OPC UA server or OPC UA Client driver for KEPServerEX can disregard this article.

OpenSSL is an open-source library used by many OPC UA applications to secure communications. KEPServerEX uses OpenSSL to secure communications with the OPC UA server and OPC UA Client driver. Recently discovered vulnerabilities in OpenSSL could impact these products by allowing a remote attacker to intercept, decrypt, and manipulate data between KEPServerEX and a UA endpoint.

The following link documents the vulnerability in OpenSSL:

The vulnerability relates to the AES-NI implementation in OpenSSL before 1.0.1t and 1.0.2 before 1.0.2h. Those versions do not consider memory allocation during a certain padding check, which allows remote attackers to obtain sensitive clear-text information via a padding-oracle attack against an AES CBC session. This can lead to unauthorized access to sensitive information.

The more accessible the OPC UA server is, the more vulnerable it is to this attack. For example, if the OPC UA server is only available on the LAN or controls network, the exposure is limited. A rogue application would need to penetrate this network and exploit the vulnerability from a compromised machine on the network. If the OPC UA server is accessible via the WAN, it is more susceptible to this vulnerability. Any machine that can access the OPC UA server on the network could exploit this vulnerability.

Because KEPServerEX only installs a Localhost UA endpoint by default, only applications running on the same machine as KEPServerEX could exploit this vulnerability. Enabling a non-localhost endpoint makes a machine more susceptible, but it depends on how accessible the OPC UA server is on the network.

Kepware addressed these issues by upgrading to OpenSSL version 1.0.2h in KEPServerEX version 5.21.112, which was released on August 16, 2016.

We apologize for any inconvenience this may cause.
Related Products
OPC UA Client

Related Protocols
OPC Unified Architecture (UA)