A Hierarchical Framework of Security Situation Assessment for Information System

Security situation assessment is an effective way to analyze the situation of an information system, which helps administrator understand the current system risk status and make policy to response in time. However, the existing researches for security situation assessment mostly focus on network. The proposed methods for network are not so suitable for information systems. This paper proposes a hierarchical security situation analysis framework for information system, based on a classical NSSA [1] (network security situation analysis) model. The framework provides a standard flow for analyzing the security situation of information system. It consists a security situation analysis model of information system, an index system used in the model proposed, and a quantitative index fusion method to calculate a security situational value. We divided information system into 3 levels: sub-system level, composition level and index level. The collected information from the index level can be combined with grey model to determine the correlation degree between each major index and secondary index. Finally we calculate the whole system security situational value level by level. We use data from Tsinghua University information system to verify the proposed model and method. The result shows that this model can reflect the current security situation of information system comprehensively.