OT systems are no longer isolated from other systems. With increasing digitalisation, OT systems are starting to depend on IT systems and external sources of information, as well as information source for business processes. This increases the need for OT systems to connect with the outside.
This whitepaper examines possible use cases and related threats of connecting to the outside. The paper also defines a best practice architecture to protect against these threats. Grid operators can use this work for their own security architecture and in risk assessments.