Firmware rewriting apparatus, firmware rewriting method, and non-transitory computer readable medium storing program

A firmware rewriting method comprising:

• a call position specifying step of specifying, among instructions described in a program of firmware stored in a memory, the instructions for changing a control flow;
• a free area specifying step of specifying a free area in a storage area of the memory, the program not being stored in the free area;
• and
• a program rewriting step of rewriting the instruction specified in the call position specifying step into a call instruction of a frequency adjustment code and writing the frequency adjustment code for calling an inspection code at a frequency corresponding to a frequency of calling the frequency adjustment code and the inspection code for performing a security check of the program in response to a call from the frequency adjustment code into the free area specified in the free area specifying step.

A non-transitory computer readable medium storing a program for causing a computer to execute:

• call position specifying processing of specifying, among instructions described in a program of firmware stored in a memory, the instructions for changing a control flow;
• free area specifying processing of specifying a free area in a storage area of the memory, the program not being stored in the free area;
• and
• program rewriting processing of rewriting the instruction specified in the call position specifying processing into a call instruction of a frequency adjustment code and writing the frequency adjustment code for calling an inspection code at a frequency corresponding to a frequency of calling the frequency adjustment code and the inspection code for performing a security check of the program in response to a call from the frequency adjustment code into the free area specified in the free area specifying processing.