Abstract: Embodiments of the present invention relate to systems and methods for optimizing and reducing the memory requirements of state machine algorithms in pattern matching applications. Memory requirements of an Aho-Corasick algorithm are reduced in an intrusion detection system by representing the state table as three separate data structures. Memory requirements of an Aho-Corasick algorithm are are also reduced by applying a banded-row sparse matrix technique to the state transition table of the state table. The pattern matching performance of the intrusion detection system is improved by performing a case insensitive search, where the characters of the test sequence are converted to uppercase as the characters are read. Testing reveals that state transition table with sixteen bit elements outperform state transition table with thirty-two bit elements and do not reduce the functionality of intrusion detection systems using the Aho-Corasick algorithm.

Abstract: Embodiments of the present invention relate to systems and methods for optimizing and reducing the memory requirements of state machine algorithms in pattern matching applications. Memory requirements of an Aho-Corasick algorithm are reduced in an intrusion detection system by representing the state table as three separate data structures. Memory requirements of an Aho-Corasick algorithm are also reduced by applying a banded-row sparse matrix technique to the state transition table of the state table. The pattern matching performance of the intrusion detection system is improved by performing a case insensitive search, where the characters of the test sequence are converted to uppercase as the characters are read. Testing reveals that state transition tables with sixteen bit elements outperform state transition tables with thirty-two bit elements and do not reduce the functionality of intrusion detection systems using the Aho-Corasick algorithm.

Abstract: The threat probability of events generated by a security device on a computer network is assessed by comparing the threat probability to a global threat probability. An abstract data type is used to describe how the events are combined to form a threat. If an event matches an unpopulated member of an instance of an abstract data type, the event is added to the instance and the probability of the instance is computed. If the probability of the instance is greater than a global threat probability, a dynamic threat assessment event is generated. A system for dynamically assessing threats to computers and computer networks system includes at least one security device that generates events, an event collection database, policy configuration information, and a dynamic threat assessment engine.