Why Securing Distributed Control Systems Is No Longer Optional

The distributed control system (DCS) is the core of industrial automation. It synchronises critical operations in power plants, chemical factories, pharmaceutical sites, and more. The system was designed to ensure process stability, high availability, and precise control—well before the concept of cybersecurity ever entered the conversation.

That’s exactly where the problem lies.

As operational technology (OT) environments become increasingly connected and remote access becomes the norm, DCS infrastructures are now exposed to risks they were never built to handle. From ransomware disrupting plant operations to unauthorised access compromising safety-critical processes, the attack surface has expanded far beyond traditional physical boundaries.

What once relied on air gaps and closed networks now demands secure identity, accountability, and traceability.

Rethinking the Role of a DCS in Today’s Threat Landscape

Distributed control systems are built to manage complex, continuous processes across a facility through decentralised intelligence. Each local controller operates semi-independently, reducing the risk of a single point of failure while enabling fast, real-time decisions at the edge.

But that same distributed nature introduces fragmented access points—each of them a potential vulnerability when protected only by default passwords or role-based logic that lacks robust identity binding. In most industrial sites, shared logins, outdated credential systems, and remote engineering workstations make it difficult to enforce accountability or even determine who accessed what, and when.

It’s not just about protecting against malware. It’s about ensuring only the right individual, at the right time, with the right authority, can execute control functions.

Common Misconceptions That Leave DCS Environments Exposed

• “The system is air-gapped.”
  Until it isn’t. Maintenance work, remote troubleshooting, and integration with IT systems often quietly punch holes in the supposed isolation.
• “We have firewalls.”
  Firewalls don’t stop a technician with shared credentials from bypassing intended controls. They don’t track identities or enforce one-time access.
• “Our engineers know what they’re doing.”
  Even the most skilled operator can’t secure a system that lacks fundamental access control and audit mechanisms.

What’s Really at Stake

When DCS access isn’t secured, it’s not just IP or data at risk—it’s uptime, safety, and regulatory compliance. A single compromised session can:

• Halt production
• Trigger cascading system errors
• Disable safety interlocks
• Breach NIS2, IEC 62443, or national security directives

And unlike IT systems, recovery isn’t as simple as restoring from backup. Physical systems may need recalibration, manual inspection, or complete shutdowns—at enormous cost.

Identity Is the New Perimeter in Industrial Control Systems

Modernising DCS cybersecurity starts with enforcing identity—not just at the network edge, but at every point of control. swIDch enables:

• Access without network dependency through OTAC (One-Time Authentication Code)
• Dynamic, non-replayable codes that bind access to specific individuals
• Authentication even on legacy equipment and offline systems
• Credential-less access that eliminates static passwords completely

Through solutions like PLC OTAC, OTAC Trusted Access Gateway (TAG), and MFA for PLCnext, it becomes possible to manage DCS access without needing to replace or retrofit every device. Security becomes part of the process layer—not just the IT layer.

Legacy Doesn't Have to Mean Vulnerable

Even if a DCS was deployed a decade ago, it doesn’t need to remain a soft target. Retrofitting modern authentication is not only possible—it’s increasingly necessary. With the right identity-first approach, it's possible to:

• Achieve compliance with NIS2 and IEC 62443
• Eliminate shared credentials across the board
• Ensure full auditability for every access event
• Improve operational safety by limiting unauthorised or accidental inputs

The Next Era of OT Security Starts with How You Log In

Industrial automation will always demand uptime, precision, and speed. But none of that is sustainable without trust—trust that the person interacting with the system is who they say they are.

Securing distributed control systems isn’t just about firewalls or segmentation. It’s about putting identity at the heart of control logic. And the companies that act now will be the ones leading the industry through the next wave of regulation, innovation, and resilience.

What Comes Next in DCS Protection

Distributed Control Systems are the foundation of modern industrial operations, managing continuous processes with high reliability and precision. From petrochemical refineries to water treatment plants, DCSs are critical not just for productivity, but for public safety.

However, their longevity is also their weakness. Many systems still operate on outdated software with minimal security features. As digital transformation accelerates and remote work becomes more common, the idea of an isolated or “air-gapped” system no longer holds up. Engineers access DCS environments remotely. Vendors are granted temporary credentials. Every convenience introduces a potential risk.

Cyber attackers are aware. From unpatched workstations to reused credentials, the attack surface keeps growing. And when a DCS is breached, the damage isn’t just digital—it's physical. Production lines halt. Safety mechanisms fail. Entire sites may need manual recovery or recalibration, driving up costs and risks.

Why Identity Is the Next Step for Operational Resilience

Traditional security controls like firewalls and role-based access were built for a different era. They help, but they don't answer the most critical questions: Who is accessing the system? Are they authorised? Can we verify and audit every action?

Identity-first security offers a new approach. Instead of relying on shared logins or static credentials, access is granted through dynamic authentication that ties each session to a verified individual. swIDch’s OTAC technology enables this even on legacy systems—without needing a network connection or major infrastructure overhaul.

This isn't just about better cybersecurity—it’s about operational trust. When every login is traceable and every action accountable, organisations gain confidence in their systems and reduce the risk of human error or insider threats.
As regulatory pressure increases under cybersecurity frameworks like NIS2 and IEC 62443, retrofitting secure identity controls is becoming essential. With lightweight solutions built for OT environments, even the most complex DCS can be modernised without disruption.

Cybersecurity doesn’t have to be a tradeoff with uptime. It can be the very thing that sustains it.