Over the past two decades, the Internet has transcended human civilization to the information age. Cyberspace has now become a part of our ecosystem, an essential and indispensable element of our life. However, with the rise of Internet users, it has also become a playground of reprobaters who are constantly threatening the computer systems with ever evolving threats. These threats target various computing platforms like PCs, laptops, tablets, mobiles, IoT devices, etc. Security agencies globally are striving hard to combat these threats but fail to keep pace with their rising complexity and variety. Artificial Intelligence (AI), which heralded the growth of smart cognitive systems in the last decade, gives hope to cybersecurity agencies to contain cyber threats. This thesis is a step in this direction. The work done in this thesis is at the intersection of AI and Cybersecurity. The following two sections, 1.1 and 1.2, describe the broad areas covered in the thesis, Cybersecurity, and AI, respectively. Subsequent sections describe the research gaps (1.3), the main contribution of the thesis (1.5), and the thesis organization (1.6).