CORE (COllaborative Review Environment) system is designed for a networked intelligent manufacturing system that uses virtual reality technology for design review, simulation and virtual manufacturing. Most virtual environment architectures, including CORE system, have mainly paid attention to the quality of service with little or no concern of information security of the virtual reality system. In this paper, we introduce CORE system and analyze architecture of the system. We find out possible security vulnerabilities according to five areas of information assurance and propose security countermeasures against the vulnerabilities.