Why VPN and MFA Alone Fall Short in Securing OT Environments

For many industrial organizations, securing remote access follows a familiar formula: deploy a Virtual Private Network (VPN), require multi-factor authentication (MFA), and consider the risk largely addressed. These controls are essential and form the backbone of secure connectivity in both IT and OT environments.

However, operational technology systems support safety-critical processes, specialized devices, and tightly coupled engineering workflows that demand far more than basic identity verification. VPN and MFA confirm who is accessing the environment, but they do not address the actions a user may take, the systems with which they can interact, or how those actions may affect physical operations. As industrial environments become more interconnected and increasingly reliant on remote capabilities, identity alone is no longer enough.

Detection Has Improved—But Recovery Remains Slow and Complex

The data reveals an important contrast. Many organizations are improving their ability to detect incidents—nearly half identify ICS/OT incidents within 24 hours, and more than 65% take containment action within the following day. This reflects stronger monitoring, better SOC alignment, and improved collaboration between IT and OT teams.

However, remediation timelines remain long. Twenty-two percent of organizations require two to seven days to fully recover, while others take months—or longer—to return to normal operations. This is not a failure of identity controls. It reflects the inherent complexity of safely restoring industrial systems.

OT Reconstitution Demands Visibility into Actions, Not Just Access

Unlike IT assets, ICS devices cannot simply be reimaged or replaced. Recovery often requires validating alarm limits, controller logic, process sequences, and operational modes against current conditions. Without visibility into what actions were performed remotely, organizations struggle to safely and efficiently reconstitute systems.

This underscores a critical requirement: OT security teams must track user actions, not just user identities.

Cloud Connectivity Expands the Remote Access Attack Surface

Cloud adoption adds another layer of complexity. Only 17% of organizations report no cloud usage across their IT/OT environments. OEM portals, predictive maintenance platforms, analytics tools, and enterprise historians increasingly provide remote access pathways that may not traverse traditional VPNs.

Only 13% of organizations have fully integrated cloud activity into monitoring and detection workflows. This is not a weakness in VPN or MFA; it reflects the reality that modern industrial architectures now include multiple authentication models, embedded agents, and third-party access channels that operate outside traditional controls.

You Can’t Secure What You Haven’t Inventoried

A particularly concerning finding: 31% of organizations do not maintain a formal inventory of remote access points.

Remote access in OT extends far beyond corporate VPNs. It includes vendor portals, OEM support channels, cloud dashboards, portable engineering laptops, contractor sessions, cellular modems, and temporary diagnostics tools. Each exists for a valid operational reason, but without centralized governance, they create blind spots.

Organizations with comprehensive remote access inventories demonstrate stronger detection capabilities, more consistent policy enforcement, and better IT/OT coordination. In OT, visibility is not optional—it is foundational.

Detecting Misuse Requires ICS-Aware Monitoring

Only 13% of organizations report full visibility across the ICS Cyber Kill Chain, with the largest gaps at remote or unmanned facilities that rely heavily on remote access.

Indicators of misuse often include after-hours sessions, unusual cloud-originated access, unauthorized PLC or HMI changes, firmware manipulation, or unexpected activity on engineering workstations. Detecting these behaviors requires tools that understand ICS protocols, engineering workflows, and normal operational patterns, capabilities that identity controls alone cannot provide.

Remote Access Must Be Treated as a Safety-Critical Function

Remote access is one of the most impactful components of industrial cybersecurity. VPN and MFA are essential, but they represent only one layer of a far more complex risk landscape.

Organizations demonstrating the highest levels of preparedness share common traits: complete remote access inventories, ICS-aware access controls, integrated IT/OT monitoring, engaged engineering teams, and regular operationally realistic exercises. They treat remote access not as an IT convenience, but as a safety-critical function requiring engineering-grade rigor.

VPN and MFA remain vital, but true OT defensibility requires controls that account for context, behavior, and consequences. By building on this foundation with ICS-specific access governance, organizations can transform remote access from a persistent risk into a transparent, resilient, and well-controlled component of modern industrial operations.