Closed security environment

A closed security environment is an "[e]nvironment providing sufficient assurance that applications and equipment are protected against the introduction of malicious logic during an IS life cycle. Closed security is based upon a system’s developers, operators, and maintenance personnel having sufficient clearances, authorization, and configuration control."

Source
National Information Systems Security (INFOSEC) Glossary (NSTISSI No. 4009 Sept. 2000).