Here are some new and required subjects for a doctoral thesis on Cyber Threat Intelligence (CTI):

1. "AI-Powered CTI: Developing Machine Learning Models for Threat Prediction and Detection"

2. "CTI for IoT Security: Investigating Threats and Developing Mitigation Strategies"

3. "Cyber Threat Intelligence Sharing and Collaboration: A Study of International Frameworks and Best Practices"

4. "Dark Web Analysis for CTI: Exploring the Role of Dark Web Markets in Cyber Threats"

5. "Developing a CTI Framework for Critical Infrastructure Protection"

6. "Investigating the Role of Human Intelligence in CTI: A Social Network Analysis Approach"

7. "CTI for Cloud Security: Identifying and Mitigating Threats in Cloud Computing Environments"

8. "Cyber Threat Intelligence and Incident Response: Developing an Integrated Framework"

9. "Threat Hunting with CTI: Developing Techniques and Tools for Proactive Threat Detection"

10. "CTI for Supply Chain Security: Identifying and Mitigating Threats in Global Supply Chains"

11. "Developing a CTI Capability Maturity Model for Organizations"

12. "CTI and International Relations: Investigating the Geopolitical Implications of Cyber Threats"

13. "Investigating the Role of Open-Source Intelligence (OSINT) in CTI"

14. "Developing a CTI Framework for Small and Medium-Sized Enterprises (SMEs)"

15. "CTI and Crisis Management: Developing an Integrated Framework for Organizations"