Al Akram Chowdhury You are going towards a very hot topic in the research community. I would advise you to thoroughly read through the below papers for a complete understanding of machine learning applications in cyber security. At the end of the papers, there are many challenges and research questions. You can pick up any of your interests. All the best.
Article A Survey on Machine Learning Techniques for Cyber Security i...
Conference Paper Cyber Threat Detection Using Machine Learning Techniques: A ...
Article Performance Comparison and Current Challenges of Using Machi...
To me, with the progressive and gradual modernization of networking systems, mechanism to attack the system to disrupt them are also becoming sophisticated like DDos attack.