Secure Space & Physical Access
This guide defines the physical security requirements for spaces housing critical OT infrastructure — including locked access, tamper-evident seals, visitor supervision and surveillance — as required for Category II and III systems.
In maritime OT, the “Perimeter” isn’t just a firewall; it’s a locked door. If an unauthorized person can physically touch a PLC or a switch, they can bypass all digital security by performing a factory reset or “man-in-the-middle” attack.
Defining the Secure Space
A Secure Space is any area housing critical OT infrastructure, such as the Bridge, ECR, or dedicated Server Rooms. To satisfy a class surveyor, the ETO must prove that these areas are not just “off-limits” by policy, but secured by physical barriers.
Administrative Controls
- Access Logs: Maintain a logbook for visitors (vendors/contractors) entering the Server Room.
- Key Management: Keys to OT cabinets must be kept in a secure locker, never left in the cabinet door.
Technical Controls
- Cabinet Security: All racks must be locked. Use tamper-evident seals for remote outstations.
- Port Security: Physically block unused RJ45 ports in public areas with plastic port locks.
Tamper Detection & Surveillance
Since 24/7 physical guarding of every PLC cabinet is impossible, we rely on evidence of tampering and tiered access controls.
Visitor & Non-Technical Access Control
E26 §4.2.4.3.2 requires that visitors — port officials, port agents, Class surveyors, PSC officers, chandlers, and any other non-crew personnel — are supervised or restricted when in spaces housing Category II and III systems. This is a separate requirement from service engineer access (covered in the Supply Chain playbook) and applies to anyone who enters an OT space without a technical role.
Who this applies to
- Port state control (PSC) officers
- Port agents and harbour officials
- Class society surveyors
- Flag state inspectors
- Ship chandlers and suppliers
- Any visitor with no assigned technical task
The two permitted approaches
- Supervision: A crew member accompanies the visitor throughout their time in any OT space — never leaving them unattended near CBS
- Restriction: The visitor is physically prevented from entering the OT space entirely — door remains locked, access not granted
Compliance Documentation
Templates supporting local control documentation and IRP integration.
Physical access controls are a recognised compensating measure under IACS E26 §3.2. The CBS Risk Assessor factors in the physical location and access level of each component — if your OT equipment is in a restricted ECR or server room, that reduces the assessed severity of network-layer findings accordingly.
Open CBS Risk Assessor →The specific regulatory requirements this playbook satisfies. Use these references when preparing for Class survey or responding to a surveyor's checklist.
