Zero Trust: Securing Your OT Environment

To begin the process of securing operational technology, organizations must adopt the “never trust, always verify” model.

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In 2021, the manufacturing industry continues to be at significant cybersecurity risk, and arguably that risk is growing. The 2021 Verizon Data Breach Incident Report found that the manufacturing industry experienced 585 cybersecurity incidents in the past year – 270 of which were confirmed data breaches. That same report also found that 85 percent of breaches (across industries) involved human error. And on top of this, a new Fortinet report found that 42 percent of OT leaders reported that their organization experienced an insider breach – up from 18 percent the prior year. 

The pandemic events of last year resulted in IT and OT digital connectivity on a wider scale than ever before as manufacturers instituted new options to enable and extend remote business activity for employees. Organizations no longer had the choice to keep OT isolated, but instead were faced with the additional cybersecurity challenges created by potentially exposing their OT systems to internet criminals. 

As IT and OT networks continue to converge and the attack vector increases, manufacturing organizations must amplify the need for cybersecurity measures – and this is where Zero Trust comes in. 

Understanding Zero Trust

To begin the process of securing operational technology (OT), organizations must adopt the “never trust, always verify” model, which insists on protection at every wired and wireless node as part of ensuring that all endpoint devices are validated. With the risk dynamics introduced today by enabled sensors for OT systems and exponential growth, Zero Trust is crucial to defending the cyber-physical environment. To elevate trust and establish a consistent security access baseline, it’s equally important to practice the principle of least privilege across both internal and external communications.

Historically, the traditional network security model was perimeter-based, so the thinking was that assets comprising the inside of the network could be trusted while assets external to the network would be treated as untrusted by default. With today’s cybersecurity landscape, that model is far too simplistic to be effective.

The Zero Trust model takes a different tack, no longer assuming trust based on location. It examines every device, user, and application interaction independently, not relying on IP address or network location. Context and identity mechanisms form the basis of trust.

OT leaders gain extra layers of enterprise boundary protection from an array of attack vectors when they insist on only the minimally required access and integrate an internal segmentation firewall at multiple points within the networks. In this manner, they achieve network visibility, along with least privileged enforcement, helping to prevent vertical or lateral movement within the target environment.

Getting Started 

To initiate the steps essential to achieving Zero Trust, OT leaders need to scrap the “trust but verify” model and instead start enforcing the aforementioned “never trust, always verify” model. Similarly, they need to implement the principle of least privilege across internal and external network communications by providing only the minimally required access.  

The integration of an internal segmentation firewall at multiple points within the network affords extra layers of enterprise protection from an array of attack vectors. This makes the practice of network security more granular while achieving greater attack resistance. In this instance, employing segmentation essentially invokes a containment strategy that restricts vertical or lateral movement within the target environment. 

Of course the foundation upon which segmentation is based combines the advantages of a Next Generation Firewall (NGFW) with the integration of intelligent switching. This is imperative for OT system owners who seek a high degree level of control and awareness of access privileges and related infrastructure communication.  

For example, when a  NGFW is properly configured with secure and scalable Ethernet switches, the yield is micro-segmentation. Again, the primary goal is to control and prohibit access or communication that is not approved by the NGFW policy. The increased investment yields network security with great depth and improved attack-resistance. 

To overcome cyberattacks that involve stealing identity, there are processes that can be implemented as a zero-trust access deterrent. OT leaders implementing multi-factor authentication (MFA) as part of this Zero Trust model can significantly raise the bar on earned trust by requiring the presence of two or more pieces of evidence or factors of authentication.  The very act of combining at least two credentials for access controls increases the difficulty of accomplishing theft via masquerade and thereby substantially enhances the level of cyber resilience. 

OT and IT network digital connectivity was clearly on the rise to a fair degree before the pandemic hit. That penchant for connectivity and data sharing was kicked into high gear for many manufacturers to necessitate and extend access to accommodate working from the home front. A stronger security paradigm became imminently critical to protect the connected OT/IT environment.

The Zero Trust model works well for this purpose, removing the static perimeter-based idea of network security with a “never trust, always verify” protocol. Combining least privilege, segmented and integrated firewalls and MFA, Zero Trust creates greater protection and visibility for manufacturing environments. By implementing this strategy, OT leaders can move forward with confidence that they’ve made major strides toward ensuring the security of their networks. 


Rick Peters is the CISO for Operational Technology, North America for Fortinet Inc.

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