MALICIOUS ACCESS-DETECTING APPARATUS, MALICIOUS ACCESS-DETECTING METHOD, MALICIOUS ACCESS-DETECTING PROGRAM, AND DISTRIBUTED DENIAL-OF-SERVICE ATTACK-DETECTING APPARATUS

A malicious access-detecting apparatus which is cable of grasping the whole aspect of an attack which can occur, before it actually occurs. A monitoring information-collecting section collects monitoring information including the network events detected by the monitoring devices on networks. A malicious apparatus group-deriving section retrieves a corresponding piece of the event information from an event information storage device, and derives, based on the retrieved piece of the event information, apparatuses that are involved in relevant detected network events which belong to the predetermined type of network events and of which addresses of senders or recipients are same, as a malicious apparatus group involved in the predetermined type of malicious access. A storage section stores information on each derived malicious apparatus group. An output section outputs a list of the each derived malicious apparatus group.