ICS/OT Vendor Management-The Risk No One Owns

 

By Muhammad Ali Khan ICS/ OT Cybersecurity Specialist — AAISM | CISSP | CISA | CISM | CEH | ISO27001 LI | CHFI | CGEIT | CDCP

In most industrial environments, vendor management is treated as a procurement task. Contracts are signed, access is granted, and systems go live. Once production starts, vendors quietly fade into the background until something breaks.

In ICS and OT environments, that assumption is dangerous.

Vendors do not just supply technology. They become part of the control system itself. They configure PLCs, maintain HMIs, manage firmware, and often retain remote access for years. Yet their role in cybersecurity is rarely defined with the same seriousness as their role in operations.

This gap shows up during outages, incidents, and recovery, when assumptions about trust collide with reality.

Why Vendor Management Is Fundamentally Different in OT

In IT, vendor access is typically limited, logged, and governed by standardized controls. In OT, vendors often require privileged access to live systems that cannot be easily isolated, patched, or restarted.

Industrial systems are designed to run continuously. Downtime is expensive, safety is paramount, and changes are tightly controlled. As a result, vendors are frequently granted exceptions, persistent credentials, shared accounts, or unrestricted remote access because “that’s how the system works.”

Over time, these exceptions become normal. And normal becomes invisible risk.

In many plants, vendors end up with more authority over critical systems than internal teams, without being treated as part of the security boundary.

Where Traditional Vendor Management Quietly Fails

Most organizations rely on familiar vendor risk processes: questionnaires, SLAs, and compliance checklists. These tools were built for IT environments. They do not translate cleanly into OT reality.

Security assessments rarely account for:

• long equipment lifecycles measured in decades
• vendor-controlled patch schedules
• proprietary protocols and tooling
• safety constraints that override security controls

Procurement contracts often define uptime and support obligations, but remain silent on incident response roles, access revocation, or post-incident accountability.

On paper, the vendor is “approved.” In practice, no one is managing what actually matters.

The Risks Vendors Introduce — Without Malice

Most OT vendor risk is not the result of negligence or bad intent. It comes from structural trust.

Common realities include:

• Vendor laptops connecting to multiple customer environments
• shared credentials reused across plants
• Emergency access is granted during outages and never revoked
• remote connections that are rarely monitored once production stabilizes

Individually, these practices seem manageable. Together, they create a condition where recovery speed, system authority, and safety assurance are partially outsourced.

In that state, an incident does not need to be sophisticated to be effective. It only needs to occur at a moment when the vendor is unavailable, unprepared, or outside your control.

When Vendor Trust Collides With Incident Response

The most uncomfortable moment in OT cybersecurity often comes during recovery.

The plant is down. Safety systems are holding. Operations wants to restart. But only the vendor has credentials to modify the PLC logic. The internal team can see the issue but cannot change it. Remote access is disabled “for security,” and the vendor engineer who understands the system is not on-site.

Six hours pass while calls are made, approvals are chased, and access is re-enabled under emergency conditions. No attacker is involved. No malware is present. The delay is caused entirely by vendor dependency that was never addressed when the system was stable.

At this point, vendor management stops being a governance issue and becomes a resilience issue. If vendor roles, access boundaries, and responsibilities were never defined ahead of time, response speed suffers, not because of malware, but because of dependency.

What Effective ICS/OT Vendor Management Actually Looks Like

Mature OT organizations approach vendor management as a security and operational control, not a procurement checkbox.

That means:

• Treating vendor access as temporary, scoped, and observable
• integrating vendors into incident response planning
• managing vendor tools as OT assets, not external utilities
• aligning security requirements with operational reality, not IT assumptions

Most importantly, it means recognizing that trust in OT must be continuously validated — not assumed.

Vendor Management Is About Power, Not Paperwork

At its core, ICS/OT vendor management is about one question:

Who can change your process when it matters most?

If the answer is unclear, unmanaged, or undocumented, then no amount of network monitoring or threat detection will compensate for it.

If a third party can change your process faster than your own engineers during a crisis, then you are leasing your control system

In industrial environments, the most dangerous risks are rarely loud. They are embedded, accepted, and invisible — until the moment they decide how fast you recover.

Final takeaway

If you cannot clearly answer these under pressure, your problem is not visibility or tooling.

• Which vendors can access your control systems?
• When did they last connect?
• what are they allowed to change?
• and how they participate during incidents?

It is that you have allowed operational authority to drift outside your organization, and you will only notice when recovery slows to a crawl.