BECKHOFF: Null Pointer Dereference vulnerability in products with OPC UA technology

By tricking clients of the mentioned products into contacting malicious OPC UA servers and thereby acting as OPC UA clients, a crash of the component can be provoked.

The mentioned products can be used as clients which contact an OPC UA server. If such connection is made with SecurityMode=None for the connection then the client can receive a malformed message during the conversation which provokes a null pointer dereference within the OPC UA stack of the product. The product crashes then by memory access violation. Though this is uncommon and not recommended, such connections with SecurityMode=None may even be used by OPC UA Servers, for example if they act as client to register at a Discovery Server.

Have your applications configured to use other than SecurityMode=None for all OPC UA connections. Avoid that these connect to an unknown OPC UA server with SecurityMode=None. In particular, avoid that your applications connect to servers which they discover via mDNS, a Local Discovery Server (LDS), an untrusted Global Discovery Server (GDS) or even trusted GDS using SecurityMode=none. Especially in the latter case an adversary might be able to apply the 'man in the middle' pattern to attack the connection and inject a bad message which triggers the vulnerability.

Please update to a recent version of the affected product.