The MITRE ATT&CK® knowledge base for ICS is now publicly available. If you've not got time to check it out now, at least click on this link and bookmark it.
This is a database of adversary tactics and techniques based on real-world observations. It contains very useful knowledge for those performing risk assessments and/or setting up monitoring.
So if you're the person responsible for security of your site's industrial networks, I strongly recommend you take a look if you aren't familiar already:
Need help getting on top of the security of your industrial networks?