SYSTEM SECURITY APPROACHES UTILIZING A HIERARCHICAL MEMORY SYSTEM

A method and system for ensuring system security is disclosed. Based on the content of the data units the method and system monitor, the method and system retrieve the states and the dependency relationships among these states that are representative of unwanted patterns. The method and system store the states and the dependency relationships mentioned above in different types of memories according to the frequency of accessing the states. The frequency is calculated by comparing a number of test data patterns with the states in a sequence specified by the dependency relationships. The method and system further identify a set of suspected data units by comparing the data units with the retrieved states in a sequence specified by the retrieved dependency relationships, wherein the content of the set of the suspected data units collectively matches any of the unwanted patterns.