Disclosed herein is an apparatus for enhancing network security, which includes an information collection unit for collecting information about states of hosts that form a network and information about connectivity in the network; an attack surface analysis unit for analyzing attack surfaces by creating an attack graph using the information about the states and the information about connectivity; a security-enhancing strategy establishment unit for establishing a security-enhancing strategy based on the attack graph; and a security-enhancing strategy implementation unit for delivering a measure based on the security-enhancing strategy to a corresponding host, thereby taking a security-enhancing measure.