As reported by CISA, in collaboration with the Australian Signals Directorate's Australian Cyber Security Centre (ASD's ACSC), the FBI, and international partners, a new joint guidance document — CI Fortify: Advice for Isolating Vital Systems — has been released targeting critical infrastructure organizations. The timing of this release is not incidental. It arrives against a backdrop of escalating adversarial activity targeting operational technology (OT) environments, including documented campaigns by Russian intelligence services and state-aligned threat actors against energy, water, transportation, and communications sectors.
Why This Guidance Matters Now
For years, the cybersecurity community has debated the adequacy of network segmentation in OT environments. The CI Fortify guidance represents a meaningful shift in the conversation — moving beyond the concept of segmentation as a passive architectural control and toward deliberate, executable isolation as an operational capability. The difference is significant. Segmentation keeps networks separated under normal conditions. Isolation is what you do when normal conditions no longer apply.
The threat landscape driving this guidance is clear. Nation-state actors — particularly those aligned with Russian and Chinese intelligence services — have demonstrated both the intent and capability to pre-position within critical infrastructure networks, waiting for geopolitical triggers to activate destructive payloads. The Volt Typhoon campaign targeting U.S. CI sectors and the sustained targeting of industrial control systems by Sandworm-affiliated actors illustrate exactly why isolation on demand must be a planned, rehearsed capability rather than an improvised response.
Who Is Most at Risk
This guidance is most urgently relevant to organizations operating in sectors where OT and IT network convergence has accelerated — particularly:
Organizations that have undergone rapid IT/OT convergence — often driven by efficiency and remote monitoring initiatives — face the highest residual risk. Many of these environments were never designed with deliberate isolation in mind, meaning connection maps are incomplete and separation points are either nonexistent or untested under crisis conditions.
The Operational Gap Nobody Wants to Talk About
The most underappreciated aspect of this guidance is its emphasis on operating in isolation for an extended period. Most incident response planning assumes network connectivity will be restored within hours or days. The CI Fortify framework acknowledges a harder reality: during a sustained geopolitical crisis or coordinated multi-sector attack, organizations may need to operate essential services in a fully disconnected state for weeks.
The question is not whether your organization can survive a network cutover — it's whether your people, processes, and technology have ever actually practiced it.
This demands a level of operational resilience planning that goes far beyond traditional IT disaster recovery. It requires documented manual operating procedures, offline authentication mechanisms, local historian data that doesn't depend on cloud connectivity, and staff who are trained to recognize and execute isolation procedures under stress.
Shield53 Recommendations
Immediate Actions
- Map your OT connectivity comprehensively. You cannot isolate what you haven't documented. Commission or refresh a full network topology of your OT environment, including all IT/OT integration points, remote access paths, historian connections, and vendor maintenance channels.
- Identify and validate separation points. For each connection identified, determine whether a clean, tested isolation capability exists — not just a theoretical firewall rule, but a documented and exercised procedure.
- Conduct an isolation tabletop exercise. Simulate a scenario where your OT environment must operate in full network isolation for 72 hours. Identify the gaps in manual procedures, authentication, and data continuity that surface.
- Review remote access to OT systems. Third-party vendor remote access is consistently one of the highest-risk integration points. Ensure all remote access paths have documented kill switches and that those switches are actually accessible during a crisis.
- Engage your supply chain. Critical infrastructure operators often depend on vendors and managed service providers whose systems are also networked into OT environments. Understand how their connectivity affects your isolation posture.
Strategic Actions
- Integrate isolation planning into your OT incident response plan as a formal, rehearsed capability — not a footnote.
- Align your program with the NIST Cybersecurity Framework 2.0's Govern and Recover functions, which explicitly address resilience planning for critical functions.
- Consider pursuing ICS/OT-specific security assessments (such as those offered through CISA's CyHy and RVWP programs) to identify exposure before adversaries do.
The release of CI Fortify is a signal, not just a resource. Allied governments are telling critical infrastructure operators plainly: the threat environment has reached a threshold where isolation capability is no longer optional. Organizations that treat this as a compliance checkbox rather than an operational imperative do so at significant risk to themselves — and to the communities that depend on their services.
