Research into the ethics of cybersecurity is an established and growing topic of investigation, however the translation of this research into practice is lacking: there exists a small number of professional codes of ethics or codes of practice in cybersecurity, however these are very broad and do not offer much insight into the ethical dilemmas that can be faced while performing specific cybersecurity activities. In order to address this gap, we leverage ongoing work on the Cyber Security Body of Knowledge (CyBOK) to help elicit and document the responsibilities and ethics of the profession. Based on a literature review of the ethics of cybersecurity, we use CyBOK to frame the exploration of ethical challenges in the cybersecurity profession through a series of 15 interviews with cybersecurity experts. Our approach is qualitative and exploratory, aiming to answer the research question "What ethical challenges, insights, and solutions arise in different areas of cybersecurity?". Our findings indicate that there are broad ethical challenges across the whole of cybersecurity, but also that different areas of cybersecurity can face specific ethical considerations for which more detailed guidance can help professionals in those areas. In particular, our findings indicate that security decision-making is expected of all security professionals, but that this requires them to balance a complex mix of technical, objective and subjective points of view, and that resolving conflicts raises challenging ethical dilemmas. We conclude that more work is needed to explore, map, and integrate ethical considerations into cybersecurity practice; the urgent need to conduct further research into the ethics of cybersecurity AI; and highlight the importance of this work for individuals and professional bodies who seek to develop and mature the cybersecurity profession in a responsible manner.