Why Remote Access to Industrial Operations Is the Biggest Unmanaged Risk
In an era marked by heightened connectivity, industrial operations find themselves increasingly balanced on a precipice of risk. Plants across various sectors have modernized, leaning heavily on third-party vendors, integrators, and remote experts for operational efficiency. Yet, despite these advancements, the practices used to grant access to industrial networks have lagged behind the increasingly sophisticated threat landscape.
Today, the connectivity that enables operational uptime and efficiency has inadvertently transformed into one of the most significant unmanaged attack surfaces within operational technology (OT). Threat actors, including those backed by nation-states, are consistently probing these access points, seeking vulnerabilities. Recent advisories from the Cybersecurity and Infrastructure Security Agency (CISA) have underscored that insecure remote access pathways represent a primary entry vector for attacks on critical infrastructure.
As a response to the escalating risks, there’s a pressing need to reconsider remote access practices from the ground up, proposing a shift towards a zero trust network access approach tailored specifically for industrial technology.
Challenges in Operational Technology
Historically, industrial technology has relied on VPNs and jump servers to provide remote access. However, these tools often create an illusion of security. VPNs, primarily designed for Information Technology (IT), were repurposed for OT environments but grant extensive network-level access. This potentially allows remote users to access critical systems such as programmable logic controllers (PLCs), human-machine interfaces, and safety instrumented systems, all on the same flat network. Additionally, jump boxes frequently go unpatched and remain poorly monitored, failing to enforce least-privilege protocols. The primary concern appears to be getting someone connected rather than ensuring that only authorized personnel interact with specific assets when necessary.
Security often takes a backseat to operational urgency. When a critical system experiences downtime, the methodical process involving VPN-based access may be too slow, prompting teams to adopt expedient workarounds. These practices can lead to a proliferation of shadow remote access tools, the circulation of shared credentials, and the normalization of temporary access points becoming permanent fixtures.
Moreover, access hygiene is frequently neglected. In many organizations, vendor accounts associated with projects from years past often remain active, and firewall rules opened for emergency support might stay inactive long after their necessity has ceased. Without centralized visibility and automated lifecycle management, these organizations accumulate security debt with each engagement.
The Intersection of Risk and Reality
Third-party vendors and original equipment manufacturers (OEMs) frequently represent one of the most significant and least regulated paths into operational technology environments. Often deploying their unique tools, devices, and shared accounts, these external suppliers underscore the need for a zero trust network access framework. This approach emphasizes identity verification before any connection is established, limiting access to specific assets, maintaining control over session durations, and ensuring comprehensive session recording.
The shift towards centralized remote operations, accelerated by the pandemic, has established a paradigm where engineers require access to controllers across multiple sites without needing to interact with historians or safety systems. Zero trust network access enables continuous posture verification and allows for granular, role-based policies to be managed centrally.
In emergency scenarios, such as a critical process alarm sounding at 2 a.m., the urgency for immediate access can lead to bypassing controls. Unfortunately, this temptation is one that cyber adversaries may exploit during times of crisis. Under a zero trust framework, pre-approved workflows and lightweight approval mechanisms lead to complete session recording. Furthermore, access is automatically revoked once the emergency window closes.
Transitioning from an IT Buzzword to Operational Practice
Zero trust is becoming an essential framework for addressing the most urgent vulnerabilities in industrial remote access. Essential principles include:
- Explicit Verification: Every user, device, and session must be authenticated based on identity, role, asset, and real-time context—never relying solely on network location for trust.
- Least-Privilege Access: Access should be limited to a specific asset and action rather than broad network segments, with no standing privileges.
- Assuming a Breach: Designing every layer so that a compromised credential cannot accidentally cascade into further systems is vital. This includes ruthless segmentation and maintaining comprehensive logging to track every action.
Tailoring Zero Trust Network Access for Operational Technology
Implementing a zero trust network access system within OT doesn’t necessitate a complete overhaul of existing infrastructures. Instead, it involves layering identity-centric, asset-level controls that can work in conjunction with legacy systems and proprietary protocols prevalent in the OT space.
Traditional VPN-based access creates a broad network pathway reliant on various assumptions, such as the validity of segmentation and that credentials aren’t shared among users. In contrast, zero trust network access champions enforcement, ensuring each session is authenticated, connections are scoped to specific assets, and privileges expire once the task is completed. Unauthorized users effectively find the attack surface has vanished.
The Importance of Gateway Placement for Zero Trust Network Access
Many zero trust solutions centralize their gateways in industrial demilitarized zones (DMZ), which can be ineffective due to distance from assets. In networks where IP addresses are reused, this configuration can necessitate exposing private IPs, thereby complicating lateral movement.
Cisco Cyber Vision’s Secure Equipment Access addresses this challenge by embedding the zero trust gateway directly into Cisco’s industrial switches and routers within the OT network. This strategy allows for localized enforcement close to each asset, effectively preventing unauthorized discovery.
A Call to Action
Organizations can no longer afford to delay the modernization of their operational technology remote access frameworks. The pressing question now is not whether to change but rather how swiftly to transition from ad hoc practices to a structured, principles-based zero trust network access approach suitable for the specific realities of operational technology.
Consider this: how many active vendor accounts currently exist within your organization? What level of access do they have, and can you provide an audit trail for every remote session conducted in the past 90 days? If the answers to these questions raise concerns, organizations must act promptly. Those that successfully navigate this transition will not only enhance their security posture but also achieve a greater level of operational resilience, ensure compliance readiness for audits, and confidently embrace industrial digital transformation.
For organizations aiming to tackle these formidable challenges, Cisco Cyber Vision’s Secure Equipment Access serves as an effective solution designed specifically for the unique demands of operational technology environments.