Abnormal frame determination device, abnormal frame determination method, and non-transitory computer readable medium

An abnormal frame determination method executed by an abnormal frame determination device connected to an electronic control unit configured to transmit data frames at a predetermined period, the method comprising:

• receiving a first data frame estimated to have been transmitted from the electronic control unit;
• calculating a receipt interval between the first data frame and a second data frame, the second data frame being a data frame received immediately before the receiving of the first data frame;
• adding a predetermined value to a determination value stored in a storage based on determining that the receipt interval is shorter than a threshold;
• and
• determining that the second data frame is an abnormal frame based on determining that the determination value reaches a limit value and the receipt interval is longer than a proximity receipt interval that is a criterion for determining whether the first data frame and the second data frame are received in proximity to each other.

A non-transitory computer readable medium storing an abnormal frame determination program comprising instructions executable by an abnormal frame determination device connected to an electronic control unit configured to transmit data frames at a predetermined period, the instructions being configured to, when the program is executed by the abnormal frame determination device, cause the abnormal frame determination device to carry out:

• receiving a first data frame estimated to have been transmitted from the electronic control unit;
• calculating a receipt interval between the first data frame and a second data frame, the second data frame being a data frame received immediately before the receiving of the first data frame;
• adding a predetermined value to a determination value stored in a storage based on determining that the receipt interval is shorter than a threshold;
• and
• determining that the second data frame is an abnormal frame based on determining that the determination value reaches a limit value and the receipt interval is longer than a proximity receipt interval that is a criterion for determining whether the first data frame and the second data frame are received in proximity to each other.