Security Engineer, OT

Fluidstack; Sacramento (CA); On-site; USD 150,000 - 210,000; Full time

Job summary

Fluidstack is building civilization-scale infrastructure for AI and needs a security expert to protect OT environments. You will threat-model OT estates, design safe network segmentation, and deploy end-to-end controls with controls engineers.

You’ll partner with hardware OEMs on security needs and guide incident response when threats reach OT layers. The role emphasizes hands-on use of OT security tools and collaboration with power, commissioning, and site teams to secure critical

Qualifications

• Experience securing substations, SCADA, or controls systems in production environments.
• Ability to model OT environments and translate results into segmentation and controls.
• Think in the Purdue Model and adapt when needed for virtualized PLCs and software-defined OT.
• Hands-on use of OT security tooling and known platforms (Claroty/Nozomi/Dragos).
• Familiarity with BMS/EPMS and cooling systems; collaboration with engineers.

Responsibilities

• Threat model OT systems and environments across the fleet: SCADA, BMS, EPMS, and power systems.
• Design architecture and segmentation to defend a gigawatt-scale OT estate.
• Deploy security controls with engineering teams for PLC code pipelines and SCADA layers.
• Advise power, controls, commissioning, and site teams; translate reviews into actionable guidance.
• Collaborate with detection/response to tune OT coverage and assist incident responders.
• Lead engagements with hardware OEMs on security requirements and supply-chain risk.

Skills

OT security experience

Threat modeling OT

Purdue Model awareness

OT security tooling

Industrial control systems

Tools

Claroty

Nozomi

Dragos

Job description

About Fluidstack

We exist to make humanity more free. For most of human history, you farmed or you starved. Technology gave people more time for the things they wanted to do, instead of things they had to do. Powerful AI will be the biggest lever for human choice we've ever built - but only if models are aligned with what humanity actually wants. There are groups building AI who don’t share these goals. Whoever deploys frontier compute infrastructure fastest will decide whether AI expands human freedom or shrinks it.

We’re singularly focused on delivering 10 to 100s of GWs of compute faster than anyone else, rethinking every layer of the stack. We acquire power, design and build data centers, and operate them - with teams spanning hardware and software. Speed and scale are our key differentiators. Come be a part of building civilization-scale infrastructure for AI.

We hire people who care deeply about this problem space.

How We Operate

Be a barrel.

Full autonomy. Own things end to end, take on scope without being asked, no permission required to operate outside your core role.

Insane urgency.

We drive everything forward as fast as possible.

Reason from first principles.

Challenge every assumption. Zero analogy thinking, no egos, the best idea wins.

Love of the game.

The frontier of AI is the most interesting problem of our time. We put in long hours at high intensity to push the frontier forward.

Build something that actually matters.

If you’re going to spend your time, spend it on something that matters to the world.

The Security Team

Examples of key problems the team is working on.

You’re securing the frontier of AI.

The model weights training on our infrastructure are the most valuable and most targeted artifacts in technology, and we’re standing up the compute to hold them faster than anyone ever has. A breach isn’t a leak, it’s the frontier walking out the door.

Build the entire security program from scratch.

Most leaders inherit someone else’s system and spend a career patching it. Here you own it end to end, bare metal to boardroom, as we scale across continents.

Your threat surface is measured in gigawatts.

The customers running on our infrastructure are building the most consequential technology in human history, and being responsible for the physical and logical security of that work makes everything else feel small.

Role Scope

• Threat model OT systems and environments across the fleet: SCADA platforms, BMS and EPMS, cooling and power systems, and the sensor networks that feed them.
• Design the architecture and segmentation that keeps a gigawatt-scale OT estate defensible: network zones, remote access paths, and the IT/OT boundary.
• Forward-deploy with controls engineering to secure operational deployments, from PLC code pipelines and virtualized controllers to the SCADA layer above them.
• Serve as the security consultant to power, controls, commissioning, and site teams as new capacity energizes, turning review requests into guidance teams can actually deploy.
• Work with the detection and response org to understand and tune OT-environment detection coverage, and respond alongside incident responders when attacks reach OT infrastructure.
• Lead engagements with hardware OEMs on product security requirements and use cases such as firmware security, tamper evidence, and counterfeit detection to address supply chain risk.

What We’re Looking For

The below is a starting point. We always make space for exceptional people, so if you don’t fit this role exactly, tell us where you would

• You’ve secured substations, SCADA, or controls systems in production: Ignition or comparable platforms, PLCs, relays, and the industrial protocols beneath them.
• You’ve threat modeled OT environments and turned the results into segmentation and controls that operators could live with.
• You think in the Purdue Model and know when to break it, because virtualized PLCs and software-defined OT don’t always fit the reference architecture.
• You’ve worked hands-on with common OT security tooling (Claroty, Nozomi, Dragos, or similar) and know what each class of tool can and can’t see.
• You know BMS, EPMS, and cooling systems well enough to hold your own with the engineers who run them.
• You’ve moved security forward in engineering teams that don’t report to you, through consultation and design review rather than mandate.

Bonus

• NERC CIP or IEC 62443 depth. Securing virtualized or containerized industrial control. Commissioning-phase security work at construction sites.

We are committed to pay equity and transparency.

Fluidstack is an Equal Employment Opportunity Employer. All qualified applicants will receive consideration for employment without regard to race, color, religion, sex, national origin, sexual orientation, gender identity, disability and protected veterans’ status, or any other characteristic protected by law.

Fluidstack will consider for employment qualified applicants with arrest and conviction records pursuant to applicable law.