The devices that consolidate inputs and outputs, taking the instructions from the operators to make changes in the field. Controllers can be programmed or updated in the field (remotely). These devices were designed as if they were in a “trusted” (the network map should show information about the trusted vs. un-trusted environments) environment. Therefore, when given a command, they obey or respond. Most do not authenticate to make sure they are receiving commands from a specific source.
Copyright: Cybersecurity & Infrastructure Security Agency