In recent years, there have been increased efforts to recruit talented K-12 students into cybersecurity fields. These efforts led to many K-12 extracurricular programs organized by higher education institutions. In this paper, we first introduce a weeklong K-12 program focusing on critical thinking, problem-solving, and igniting interest in information security through hands-on activities performed in a state-of-the-art virtual computer laboratory. Then, we present an inquiry-based approach to design hands-on activities to achieve these goals. We claim that hands-on activities designed based on this inquiry-based framework improve K-12 students’ self-efficacy in cybersecurity as well as their problem-solving skills. The evaluation of the program showed that the participants made significant progress towards achieving the learning outcomes of the program and developed self-efficacy in cybersecurity.