The most important factor for sustainable development of secure IT services is security training for systems development staff. Security training helps to ensure that the staff members are aware of the security risks, requirements, and best practices that affect the IT services they develop. Security training also helps to improve the security skills and knowledge of the staff members,and to foster a security culture and behavior within the development team. Security training can also help to prevent or reduce security defects, vulnerabilities, or incidents in the IT services, and to enhance the security performance and quality of the IT services. Well-documented business cases, security architecture principles, and secure coding practices are also important factors for sustainable development of secure IT services, but they are not as important as security trainingfor systems development staff. References = Risk and Information Systems Control Study Manual, 7th Edition, Chapter 5, Section 5.1.1.2, page 2291

1: ISACA Certified in Risk and Information Systems Control (CRISC®) Exam Guide, Answer to Question 653.