CyberCertPrepOT Security FundamentalsOT Fundamentals: Securing Industrial Control SystemsEASYFree question
A field technician finds a PLC running production with its physical key switch left in the PROGRAM position. From a hardening standpoint, why should the switch be returned to RUN once commissioning is complete?
- A.PROGRAM mode disables the controller's Ethernet port and prevents the HMI from polling tags
- B.RUN mode encrypts all Modbus traffic leaving the controller
- C.PROGRAM mode allows remote logic downloads and online edits, so leaving it engaged lets an attacker push unauthorized ladder logic to the controller
- D.RUN mode is required for the controller to accept firmware signature verification
Why C is correct
Many PLCs use a physical key switch where PROGRAM (or REMOTE) permits logic downloads and online edits, while RUN blocks unauthorized program changes. Returning the switch to RUN is a basic least-functionality hardening step that forces a deliberate physical action before code can be altered.
Know someone studying for OT Security Fundamentals? Send them this one.