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The IT Tether: What Actually Stops Your Line
Roger Hill ·
The IT Tether is a five-part executive briefing by Roger Hill, CEO of Hillstrong Group Security. It argues that the systems most likely to stop a production line sit above the control network, in ERP, MES, virtualization, and remote access, and that OT programs scoped to Levels 0 through 3 leave them out. It is written for plant and OT leaders, CISOs, and the COOs and CFOs who approve OT security budgets.
What is inside
- Chapter 1. The line stopped and nobody touched a PLC
- Chapter 2. Your ERP is a plant floor control system. Nobody scoped it that way.
- Chapter 3. The hypervisor under your plant floor
- Chapter 4. Who can still log into your factory at 2 a.m.
- Chapter 5. From asset inventories to stop-the-line maps
Order, host, and access
Roger names three strands. Order covers ERP and MES, which decide what the line builds and whether a pallet can ship. Host covers the virtualization cluster that now carries HMI servers, historians, and engineering workstations; if that cluster is encrypted, the PLC keeps running and nobody can see it. The eBook cites Huntress data showing hypervisor involvement in ransomware encryption rising from 3 percent of cases in the first half of 2025 to 25 percent in the second half. Access covers every path into the plant: the SSL VPN, the OEM’s remote tool, the integrator’s shared jump host account, and the cellular modem on a vendor skid.
Count what the line depends on
An asset inventory lists what you own. A stoppage comes from what you depend on. Roger asks for one page per line that names each enterprise dependency, its owner, and a restoration time somebody has timed. Two controls pay across all three strands: one privileged access review run against the map, and a restart sequence decided before an incident.
A closing self-test
Each chapter ends with actions for plant leaders, CISOs, and executives. The last asks three questions at your highest-value site. Roger reports that in most plants he walks, access is the strand nobody can answer.
To plan and test restoration by line, see OT disaster recovery and business continuity planning. To find the identity paths into your plants, see the Active Directory exposure audit.
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