ICS Advisories

Risk evaluation

The affected products can act as OPC UA client or server and are vulnerable to two different kind of attacks via the OPC UA protocol. For both cases the attacker can send packets via the OPC UA protocol without the need to authenticate and 1. provoke a stack overflow resulting in denial of service of the product or 2. make the product disclose information to the attacker without authorization.

Mitigation summary

Consider limiting access to the network communication ports of affected server products. Also consider limiting where the affected client products are allowed to connect to. For example, this can be achived with Windows' built-in firewall by incoming rules for servers and outgoing rules for clients. Consider to minimize the ability of an attacker to hijack communication establishment from a client to a server. For example this can be achieved with the help of zones and conduits: Try to keep servers and clients within the same network zone and prevent intrusion into that zone. Try to enclose communication establishment within conduits like VPN channels (where one conduit can serve for many OPC UA connections) and prevent attackers from intruding into such channels. Consider updating the .NET Framework.