Abstract: A system dividing unit (110) divides a target system into a plurality of sub-systems. A root system selection unit (122) selects a sub-system in which a threat on security occurs, as a root system from among the plurality of sub-systems. A root tree generation unit (131) generates an attack tree of the root system, as a root tree. A descendant system selection unit (132) selects one sub-system or more located on an intrusion course to the root system, as one descendent system or more from among the plurality of sub-systems. A descendant tree generation unit (133) generates one attack tree or more corresponding to the one descendent system or more, as one descendent tree or more. A sub-attack tree integration unit (140) integrates the root tree and the one descendent tree or more, to thereby generate an attack tree of the target system.

Abstract: A system dividing unit (110) divides a target system into a plurality of sub-systems. A root system selection unit (122) selects a sub-system in which a threat on security occurs, as a root system from among the plurality of sub-systems. A root tree generation unit (131) generates an attack tree of the root system, as a root tree. A descendant system selection unit (132) selects one sub-system or more located on an intrusion course to the root system, as one descendent system or more from among the plurality of sub-systems. A descendant tree generation unit (133) generates one attack tree or more corresponding to the one descendent system or more, as one descendent tree or more. A sub-attack tree integration unit (140) integrates the root tree and the one descendent tree or more, to thereby generate an attack tree of the target system.

Abstract: An evaluation tree generation unit (101) generates as an evaluation tree, an attack tree about an information system, which is based on inference using predicate logic. A gold tree generation unit (102) generates a gold tree which covers an intrusion route to the information system and reflects an intrusion procedure for the information system, by using network configuration information indicating a network configuration of the information system and intrusion procedure information indicating an intrusion procedure assumed in intrusion into the information system. A tree comparison unit (103) compares the evaluation tree with the gold tree.

Abstract: In an input error detection device (100), a selection unit (108) selects a group of words that appear common to a system specification document (117) describing a specification of an information system in a natural language, and an analysis object document (116) describing at least either one of analysis device input information (111) being input information to an analysis device that analyzes the information system, and analysis device output information (112) being output information from the analysis device, in a natural language. A learning unit (109) learns a meaning of an individual word in each of the system specification document (117) and the analysis object document (116), wherein the individual word belongs to the group of words selected by the selection unit (108).