Use Case
Protecting Distributed Control Systems from Unmonitored Controller Mode Changes
Industry: USE CASE | CHEMICALS
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Protecting Chemical Processing Operations from Unmonitored DCS Controller Mode Changes
A DCS controller could be switched from Run to Program mode from an everyday operator workstation — and nobody would have known.
A chemical processing site running a continuous reactor and distillation process on a distributed control system found, during a routine architecture review, that its Safety Instrumented System (SIS) shared network infrastructure with the DCS instead of standing apart from it as an independent layer.
Shieldworkz verified true separation between the two and added monitoring for the controller state changes that had never been watched before.
Value proposition: Verify true independence between the DCS and safety instrumented system, monitor controller mode and configuration changes, and ensure unauthorized or accidental changes are caught immediately rather than discovered later.
Chemical Industry OT Security Challenges
Chemical processing environments depend on distributed control systems and safety instrumented systems to operate and protect continuous processes. During an architecture review, the site identified several gaps between documented process-safety assumptions and the actual OT environment.
Shared BPCS/SIS Infrastructure
The safety instrumented system, meant to be an independent layer, shared switches and parts of the same subnet as the DCS.
Unmonitored Controller Mode Changes
DCS controllers could be switched between Run and Program mode from a standard engineering workstation with no approval or log.
One Workstation, Two Roles
The same engineering workstation configured both process control logic and safety logic, with no separation of duties.
No Controller State Baseline
Nobody could say what a normal pattern of mode changes or configuration downloads looked like across either unit.
PSM/RMP Documentation Gaps
An upcoming process safety management audit expected evidence of monitoring and access control around safety-critical systems.
Understanding the Chemical OT Risk Landscape
On paper, the safety system was independent. On the network, it was not quite as separate as the process safety documentation assumed.
The chemical processing site operated continuous reactor and distillation processes on a distributed control system. Its safety instrumented system shared network infrastructure with the DCS rather than standing apart from it as an independent layer.
At the same time, DCS controllers could be switched between Run and Program mode from a standard engineering workstation without approval or logging. The same workstation also configured both process-control logic and safety logic.
Without visibility into controller state changes or configuration downloads, the site could not establish what normal activity looked like or immediately identify unauthorized or accidental changes.
Shieldworkz addressed these gaps through passive asset discovery, SIS independence verification, OT NDR and continuous monitoring, controller state-change detection, OT vulnerability assessment, IEC 62443 zone and conduit modeling, engineering role separation, change-approval workflows, PSM/RMP compliance mapping, and managed OT SOC monitoring.
Common Cyber and Operational Risks Affecting Chemical Processing
DCS controllers switched between Run and Program mode without approval or logging
Shared switches and subnet infrastructure between BPCS/DCS and SIS
One engineering workstation configuring both process-control and safety logic
No established baseline for normal controller mode changes or configuration downloads
Configuration downloads and program uploads occurring outside approved windows
Insufficient separation of engineering roles for process and safety logic
Limited visibility into controller state and configuration changes
How Shieldworkz Solves Chemical DCS & SIS Security Challenges
Shieldworkz delivers an end-to-end OT program covering discovery, separation, monitoring, compliance support, and managed OT security.
Passive Asset Discovery
Every DCS controller, SIS controller, and engineering workstation is mapped across the reactor and distillation units.
SIS Independence Verification
BPCS and SIS network paths are reviewed and confirmed as truly independent, not just documented as such.
OT NDR & Continuous Monitoring
Traffic is monitored for configuration downloads and program uploads occurring outside approved windows.
Controller State Change Detection
Alerts are specifically tuned to Run/Program mode transitions and logic changes on DCS and SIS controllers.
OT Vulnerability Assessment
DCS and SIS controller firmware and workstation software are reviewed for exposure tied to the shared network path.
IEC 62443 Zone & Conduit Model
Zones are defined to separate BPCS, SIS, and engineering access for each unit.
Engineering Role Separation
Workstation access is reworked with separate credentials for process-logic versus safety-logic changes.
End-to-End Chemical DCS Protection Capabilities
DCS & SIS Asset Visibility
Every DCS controller, SIS controller, and engineering workstation mapped across the reactor and distillation units.
DCS/SIS Independence Verification
Network-level confirmation that BPCS and SIS paths are truly independent
Controller State Monitoring
Detection of Run/Program mode transitions and controller state changes.
Configuration Change Monitoring
Monitoring of configuration downloads and program uploads outside approved windows.
Engineering Access Governance
Separate credentials for process logic and safety logic changes.
OT Vulnerability Assessment
Review of DCS and SIS controller firmware and workstation software for exposure.
IEC 62443 Zone & Conduit Alignment
Zones defined to separate BPCS, SIS, and engineering access.
The Business Value of Verified DCS & SIS Integrity
Knowing that DCS and SIS environments are actually separated — and being able to continuously verify controller activity — provides value beyond cybersecurity.
True Safety-System Independence
True independence between the DCS and safety instrumented system was confirmed and enforced.
Complete OT Asset Visibility
Every DCS controller, SIS controller, and engineering workstation was mapped across both process units.
Real-Time Controller Visibility
Controller mode changes are now logged and flagged in real time, compared with having no visibility previously.
Stronger Engineering Accountability
Engineering access is separated into distinct roles for process logic and safety logic changes.
Improved PSM/RMP Audit Readiness
PSM/RMP audit documentation was prepared ahead of the site's next process safety review.
Secure Your Chemical Processing Environment
Your DCS and SIS should be independent in practice, not just on paper.
Verify true DCS and SIS separation. Monitor controller mode and configuration changes. Strengthen engineering access and maintain visibility across your critical process-control environment.
Talk to Shieldworkz OT Security Experts about protecting your distributed control systems from unmonitored controller mode changes.
Schedule Your Free OT Security Consultation
Get the Full Chemical DCS Protection Use Case Understand how Shieldworkz helped a chemical processing site verify true DCS/SIS independence, detect previously unmonitored controller mode changes, separate engineering roles, and prepare PSM/RMP audit documentation ahead of the site's next process safety review.
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