VEHICLE SYSTEM AND CONTROL METHOD

A vehicle system (100) is a vehicle system used for a vehicle, and includes: a plurality of in-vehicle apparatuses (110) installed in the vehicle; and a controller (120) that, in accordance with a depth of penetration of a malicious attack carried out on the plurality of in-vehicle apparatuses (110), changes at least one of a communication method with an outside of the vehicle, a defense method against the malicious attack, or a storage method for logs pertaining to the plurality of in-vehicle apparatuses (110).