A Control UI is the operator-facing interface used to manage an agent or automation system. It typically exposes functions such as session selection, permission grants, browser control, approval prompts, and status monitoring. In platforms that can act inside web sessions, the Control UI is often the place where an operator decides what the agent may read, click, submit, or retain.
It matters in cyber security because the Control UI can become part of the trust boundary. If it is poorly designed, an attacker may abuse it through session hijacking, confused-deputy behavior, or overly broad approvals. Defenders harden it with role-based access, clear consent flows, credential masking, audit logging, and strict separation between users, sessions, and browser profiles. In real deployments, the Control UI is where least-privilege policy becomes practical enforcement.