Abstract: An apparatus includes a memory, and a processor coupled to the memory and configured to specify a communication source device that performs a plurality of traffic confirmations of communications with a plurality of first devices, and control to discard a plurality of first authentication requests for the plurality of first devices generated by the communication source device after performing the plurality of traffic confirmations of communications.

Abstract: A log analysis device that classifies, based on a log collected from a network device, a plurality of attack target communication devices receiving attacks from an attack source communication device includes a correlation coefficient calculation unit that calculates, based on the log, a correlation coefficient relating to the number of the attacks in a time period during which the attacks were carried out for a combination of the plurality of attack target communication devices, the time period including a detection time at which and the detection period of time during which the network device detected the attack, and an extraction unit that extracts, as a high-correlation communication device group, a combination of the plurality of attack target communication devices, for which the correlation coefficient is equal to or greater than a prescribed threshold and of which the attack source communication device is identical in the time period.

Abstract: An apparatus includes a memory, and a processor coupled to the memory and configured to specify a communication source device that performs a plurality of traffic confirmations of communications with a plurality of first devices, and control to discard a plurality of first authentication requests for the plurality of first devices generated by the communication source device after performing the plurality of traffic confirmations of communications.

Abstract: The method is for detecting theft of authentication information for a communication device that provides a service for a user. The method includes storing, for each log-in request, a record of information on a log-in request source, authentication information that the log-in request source submits to the communication device when the log-in is performed, and information indicating a success or failure of the log-in using the authentication information; receiving information on an attack source against the communication device, from a management device of a network in which the communication device exists; determining that authentication information in the record is stolen by the attack source when information that indicates success of the log-in is stored in the record, the record including information on the log-in request source which is matched with the information on the attack source; and outputting the authentication information that is determined to be stolen.

Abstract: A log analysis device that classifies, based on a log collected from a network device, a plurality of attack target communication devices receiving attacks from an attack source communication device includes a correlation coefficient calculation unit that calculates, based on the log, a correlation coefficient relating to the number of the attacks in a time period during which the attacks were carried out for a combination of the plurality of attack target communication devices, the time period including a detection time at which and the detection period of time during which the network device detected the attack, and an extraction unit that extracts, as a high-correlation communication device group, a combination of the plurality of attack target communication devices, for which the correlation coefficient is equal to or greater than a prescribed threshold and of which the attack source communication device is identical in the time period.