That is, when it is determined at step S225 that the current CPU usage of the one-way fuzzing target is equal to the previous CPU usage thereof, the transmission rate of fuzzing data may be decreased at step S226. When the current CPU usage of the one-way fuzzing target is not equal to the previous CPU usage thereof, the transmission rate of fuzzing data may be increased at step S227.

Also, at step S220, the transmission rate of fuzzing data may be set at step S228.

That is, at step S228, the transmission rate of fuzzing data, set based on the CPU usage, may be set as the current transmission rate of fuzzing data.

Also, at step S230, the effectiveness of the fuzzing data may be determined.

Here, at step S230, the effectiveness of the fuzzing data may be determined based on whether the data that the one-way-fuzzing-target-processing unit 11 transmits to the target counterpart device is collected.

Because fuzzing data consumes more fuzzing time without crashing the target counterpart software, information about the effectiveness of the currently transmitted data may be identified.

Here, at step S230, in order to determine the effectiveness of the fuzzing data, the communication interface between the one-way fuzzing target and the target counterpart software is monitored at steps S231 to S234, or the memory of the one-way fuzzing target is monitored, whereby the effectiveness of the fuzzing data may be determined at steps S235 to S239.

Referring to FIG. 5, at step S230, whether the one-way fuzzing target transmits data may be checked at step S231.