Advanced Persistent Threat (APT) attacks are complex, employing diverse attack elements and increasingly intelligent techniques. This paper introduces a tool for security risk assessment specifically designed for these attacks. This tool assists security teams in systematically analyzing APT attacks to derive adaptive security requirements for mission-critical target systems. Additionally, the tool facilitates the assessment of security risks, providing a comprehensive understanding of their impact on target systems. By leveraging this tool, security teams can enhance defense strategies, mitigating potential threats and ensuring the security of target systems.

With the significant increase of various cyber threats, the strategies of the attacks are becoming more diverse. In particular, more attention needs to be paid to Advanced Persistent Threat (APT) attacks since these attacks are continuously performed on a specific target for an apparent purpose through numerous tactics and techniques without being discovered for a long time. Although it is difficult to detect and respond to such APT attacks, it is more challenging to elicit security requirements that sufficiently reflect these complex characteristics for proactive defense. To address this problem, we propose a tool that recommends security requirements for APT attacks using the Case-Based Problem Domain Ontology specialized for APT attacks.