Securing OT Networks in Grain Elevators: 5 Best Practices

Grain elevators play a crucial role in agriculture, and their operational efficiency hinges on well-protected Operational Technology (OT) networks. David Smit, an OT architect at Interstates, presented insights at GEAPS Exchange 2024, highlighting the distinctions between OT and IT networks, the risks they face, and actionable strategies to mitigate threats. Here's how organizations can secure these vital systems:

1. Establish a Layered Defense with Firewalls

Firewalls are the first line of defense, safeguarding against unauthorized access. Smit underscores the necessity of at least one OT firewall, preferably with layers:

“I have a couple of nonnegotiables, and having an OT firewall is a nonnegotiable,” Smit said. “You won’t convince me otherwise—you absolutely need to have an OT firewall.”

He emphasized the importance of layered firewalls, including perimeter firewalls for external access and zone-specific firewalls to manage and protect internal connections.

2. Isolate and Segment Networks

Proper network segmentation separates critical OT assets from corporate IT zones. Using demilitarized zones (DMZs) isolates sensitive systems and prevents lateral movement of threats.

“By implementing a demilitarized zone (DMZ), manufacturing zones can be isolated from corporate zones, preventing direct communication between IT and OT networks,” Smit explained. He also recommended placing critical resources like Active Directory servers and historians in these secure zones to ensure controlled access.

3. Adopt Software-Defined Networking (SDN)

Software-Defined Networking (SDN) enhances visibility and control, enabling rapid quarantining of infected devices and improving response to emerging threats.

“SDN allows for the creation of separate zones and the immediate quarantine of compromised devices, reducing the risk of widespread infections,” Smit noted. Its flexibility supports secure zone creation and granular traffic management.

4. Foster Cybersecurity Awareness Among Team Members

Team members can be the weakest link or strongest defense against cyberattacks. Smit emphasized the growing threat posed by sophisticated phishing campaigns and AI-crafted scams:

“AI or ChatGPT is changing this threat landscape,” he said. “I envision three years from now, the percentage of compromised accounts will be much higher due to growing AI capabilities. Phishing emails are no longer from somebody crafting messages claiming the police must collect your overdue parking tickets. AI is now making language models that will look incredibly real and can act like an email from your supervisor. They can learn what tools and systems your company uses and expertly craft phishing emails with that information.”

Training programs on phishing recognition, supported by regular simulations, prepare teams to counter these evolving threats.

5. Monitor Traffic for Anomalies

Continuous traffic monitoring with Intrusion Detection Systems (IDS) and Intrusion Prevention Systems (IPS) helps identify and mitigate potential security incidents. Smit recommends tools like Shodan.io to locate and address exposed assets promptly:

“I encourage you to go to Shodan.io and search for your company’s IP ranges,” Smit said. “This site shows all the devices and network infrastructure that are publicly exposed, including PLCs. If you have assets on Shodan.io, get rid of them immediately or unplug them until you have a migration plan to get them off the network. They are sitting ducks waiting for someone to find your information that’s available on the internet now.”

Layered Security is Key

The interconnected nature of modern OT networks requires a comprehensive, layered security approach. Smit concluded with an emphasis on defense in depth:

“Don’t just do one of them—do all of them,” Smit advised. “Because if you just put SDN on your network, you just put a controls firewall on your network, just run antivirus on your system, or are just patching, it does not mean you will be all right. Defense in depth is about layering all those together.”

By integrating multiple strategies—firewalls, segmentation, SDN, employee training, and monitoring—grain elevator operators can safeguard their operations, protect workers, and ensure system integrity.

This article was originally published in Feed & Grain.