The Professional Risk Manager (PRM) certification is an online certification program for risk managers. To become a PRM, you need to pass four exams, each one testing you on different areas. The exam is conducted online and there is no specific rules on how you prepare for the exam. PRMIA, the body that conducts the exam, provides a detailed syllabus and exam pattern and in the exam the students are tested on the syllabus.
PRMIA also provides a PRM Handbook which is the official book for PRM Certification. There is no other prescribed book. So candidates have a choice of either studying using the handbook or purchase from the many available online courses. Finance Train also has a collection of tutorials prepared specifically for PRM Exams.
For PRM Exam 4, which is about case studies, there is list of online resources available on PRMIA website. You can also find these risk management case studies here.
PRMIA also conducts another exam called Associate PRM. This certification is one level below the the PRM exam. For Associate PRM exam, the official reading is The Essentials of Risk Management. This is an extremely well written book and is the prescribed reading for APRM exam. Again case studies can be studied from the online material.