In this presentation, we will point out the challenge of inconsistent information in the design, implementation, and verification phases of ISO/SAE 21434 and present the concept of an attack knowledge base to show how it can assist in those phases. We will also demonstrate the practical application of the attack knowledge base through case sharing. This presentation aims to provide a solution for automakers to address information inconsistencies and help create an in-vehicle environment that is both secure and resilient.