Abstract: When industrial control systems (ICS) in petrochemical enterprise access other information systems connected to Internet, they may suffer cyber attacks from external networks. In order to achieve secure data exchange between ICS of petrochemical enterprise and its corporate networks, a non-network formula which employed unilateral data transmission method is discussed in this paper. It discusses the principles of unilateral data transmission method and many security policies employed. In addition, the paper offers tests to prove that non-network formula can protect ICS in petrochemical enterprise from being tampered or attacked by hackers, Trojans or virus from Internet, and the design could ensure the safe running of ICS in petrochemical enterprises.

Key words: industrial control systems (ICS), cyber attack, non-network connection, unilateral data transmission, SCADA