Legacy systems and remote access are just the start. Discover the six urgent cybersecurity priorities every industrial operation must address now to prevent downtime and breach
That faint alarm in the back of your mind is right: your industrial network is more exposed than you think.
The convergence of IT and OT, the relentless pressure for connectivity, and the sophistication of modern threats have created a perfect storm. Ransomware gangs no longer just lock files; they target PLCs to halt production. Espionage campaigns don’t just steal data; they lurk in your SCADA network, waiting to disrupt physical processes. The old playbooks - air gaps, flat networks, and trust - are not just obsolete; they are dangerous.
After analyzing the evolving threat landscape and the realities of modern industrial operations, six critical priorities have emerged. These are not items for a future wish list. They are the foundational pillars that demand your immediate focus. This is your strategic blueprint.
The very feature that enables global expertise and efficient maintenance has become the most exploited entry point for attackers. Unsecured Remote Desktop Protocol (RDP) sessions, vendor portals with weak credentials, and broad network-level VPNs are the digital equivalent of leaving a master key under the mat.
The problem isn't remote access itself; it's how we've implemented it. Granting a third-party integrator full network access to service a single drive is a catastrophic overprovision of privilege. Modern adversaries know this and specifically scan for these vulnerable connections.
The shift is from broad network access to granular, asset-specific connectivity. The solution lies in adopting a Zero-Trust framework, where every connection attempt is verified, and access is granted on a least-privilege basis. Imagine a system where a vendor engineer is granted access to one specific HMI for a predefined four-hour window, with every keystroke logged and monitored. This isn't a futuristic concept; it's the new standard for secure remote operations that neutralizes the most common path of entry.
You cannot secure, monitor, or manage what you don't know exists. It’s a simple, undeniable truth, yet many industrial networks contain a shocking number of "shadow" assets - unauthorized devices, forgotten test equipment, or legacy PLCs that never made it into the inventory.
These blind spots are more than an administrative headache; they are unmonitored attack paths. An unauthorized device can be a rogue access point. An unaccounted-for engineering workstation can be the launchpad for a lateral movement attack. Without a dynamic, accurate asset inventory, your security efforts are built on quicksand.
The goal is not just a list; it's a living, breathing network map. This is achieved through passive monitoring techniques that listen to network traffic - using protocols like CIP Identity or LLDP - to identify every device without sending a single disruptive packet. Knowing exactly what you have, where it is, what firmware it runs, and how it communicates is the absolute prerequisite for every security action that follows, from patching to segmentation.
The myth of the protective air gap has been shattered by modern operational demands, where data must flow seamlessly from the sensor to the cloud. This connectivity, however, has exposed a critical flaw in many industrial operations: the flat network. In such an architecture, a single breach—like a phishing email in the corporate office - can spread unimpeded to critical control systems, transforming a limited IT incident into a catastrophic plant-wide shutdown.
The foundational strategy to contain this risk is OT network segmentation. This involves building deliberate internal boundaries, starting with an Industrial Demilitarized Zone (IDMZ) to securely broker data between IT and OT networks. Within the control environment, microsegmentation takes this further by creating isolated enclaves for specific processes, ensuring an incident in one area, like packaging, cannot spread to another, like batch reactor control.
This architectural shift moves beyond mere perimeter defense to create a defensible interior. By replacing the "every door is open" model of a flat network with controlled checkpoints, organizations can drastically limit the blast radius of any security incident, maintain operational continuity in unaffected areas, and build a network that is both secure and resilient.
At the heart of most industrial operations lies a profound paradox: the most critical systems are often the most vulnerable. Decades-old PLCs, RTUs, and DCS controllers were engineered for reliability and longevity in an era before cyber threats. They lack the processing power or architectural design for modern encryption, and their firmware often cannot be updated without risking operational stability.
The traditional IT mandate of "patch Tuesday" is a fantasy here. You cannot install an antivirus on a legacy PLC. This forces a fundamental shift in strategy: from changing the asset to changing the environment around the asset.
The focus moves to robust compensating controls. This includes:
This layered defence creates a secure fortress for assets that are, by themselves, inherently insecure.
The industrial protocols that form the foundation of your operations - Modbus TCP, PROFINET, DNP3 - were engineered for reliability in an era of isolated networks, not for today's security threats. This legacy creates a fundamental design flaw: they inherently trust any command they receive. These critical protocols transmit instructions in clear text, completely lacking the authentication to verify the sender or the integrity checks to prevent malicious tampering.
This vulnerability is not theoretical. An attacker who gains a foothold on your network can easily eavesdrop on operations to learn process patterns. More dangerously, they can spoof a legitimate master device to send malicious "stop," "override," or "dangerous setpoint change" commands directly to your controllers. Your PLCs will obediently comply, unable to distinguish a legitimate command from a catastrophic one.
Standard IT security tools are blind to this layer of communication. Effective defense requires a protocol-aware approach. Specialized Industrial Intrusion Detection and Prevention Systems (IDS/IPS) perform deep packet inspection to understand the actual semantics of the communication. By establishing a behavioral baseline of "normal" operations, they can flag or block anomalous commands - such as a write to a critical register from an unauthorized IP - securing the inherently vulnerable language of your control systems.
The most sophisticated technical controls can be undone by a single click on a phishing email or the use of a shared, default password. The human element - whether through inadvertent error, lack of training, or malicious intent - remains one of the most significant vulnerabilities in any system.
In OT environments, this risk is amplified. Engineers often require high-level access to perform their duties, and the cultural divide between OT and IT can lead to inconsistent security policies. A targeted "spear-phishing" attack against a control system engineer can yield credentials that are far more valuable than those of a standard office worker.
Building a "Human Firewall" requires a dual approach of technology and culture. Technologically, this means enforcing Identity and Access Management (IAM) principles: multi-factor authentication (MFA), role-based access control (RBAC) to ensure least privilege, and session recording for critical systems. Culturally, it demands ongoing, OT-specific security awareness training and fostering a collaborative environment where OT and IT share the responsibility for cybersecurity.
Answering some of the key questions asked.
Absolutely. Attempting segmentation without a complete asset inventory is like building walls in a city you haven't mapped. You will inevitably break critical communications, causing operational downtime. A living asset inventory tells you what needs to talk to what, making your segmentation strategy accurate and effective from the start.
Yes, and it's more scalable than the alternative. A modern Zero-Trust Network Access (ZTNA) solution simplifies the process. Instead of managing complex VPN clients and firewall rules, you can send a vendor a secure, time-limited link. They click it, authenticate, and are dropped directly onto the one device they need. It reduces your administrative overhead while drastically improving security.
While the vulnerability in the device may be permanent, the exploit path is not. This is the core of the compensating control strategy. By using network-level virtual patching, strict segmentation, and protocol monitoring, you are building layers of defence that prevent an attacker from ever reaching the PLC's vulnerability. You're making the exploit path so difficult that attackers move on to softer targets.
The key is using passive monitoring tools like network TAPs (Test Access Points) or switch SPAN ports. These create a copy of the traffic for your monitoring and IDS tools without introducing latency or a single point of failure into the live network. The control traffic continues unimpeded, while your security team gains full visibility.
OT environments have unique constraints: older HMIs may not support modern authentication agents, and interrupting an engineer during a critical process for an MFA push could have safety consequences. The implementation must be tailored. This might mean applying MFA at the network gateway level for remote access or using specialized IAM systems that can manage credentials for both users and machines (PLCs, HMIs) without disrupting real-time operations.
AI is a powerful tool, particularly for anomaly detection (Pillar #5), but it is not a silver bullet. AI models require the clean, structured data that comes from having a solid asset inventory (Pillar #2). Their alerts are useless without a skilled human who understands process logic to interpret them. AI will augment your efforts, but it cannot replace the foundational work of building a secure architecture.
These six pillars are not isolated projects; they are interconnected layers of a unified defence strategy. Addressing them requires a shift from reactive firefighting to proactive, architectural security.
The knowledge to build this resilient operation exists today. The time to act is now.
Subscribe to the Link & Layer | Smart Learning Hub to receive exclusive, in-depth content that breaks down each of these pillars. We provide the actionable insights and strategic guidance you need to transform your industrial cybersecurity from a persistent worry into a competitive advantage.
Unsecured vendor RDP and VPNs are the primary entry for ICS attacks. Discover how to implement zero-trust remote access that enables experts without exposing your control network
Unknown devices create unmonitored attack paths in industrial networks. Discover passive discovery techniques to build a dynamic OT asset inventory without disrupting operations
Securing remote access for legacy PLCs is the critical, often overlooked, frontier in industrial cybersecurity. This guide reveals a practical, defense-in-depth strategy to protect your vital assets without a full-scale rip-and-replace