What is The Purple Book Community's Scalable Software Security Maturity Model (S3M2)?

Purple Book Community
June 29, 2023

The Purple Book Community's Scalable Software Security Maturity Model (S3M2) is a framework designed to help organizations assess and improve their software security practices. It provides a structured approach to measuring and enhancing an organization's maturity in software security, focusing on scalability and community collaboration.

  • S3M2 emphasizes scalability and community collaboration, meaning it aims to provide a framework that can be adapted and applied to organizations of different sizes and industries. It also encourages organizations to engage with the software security community, share knowledge, and leverage collective expertise to enhance their security practices.

The model is broken down into three major categories with sub-categories beneath each of them:

  • People – Relates to the people aspect of software development organizations and addresses the needs for awareness, training, and Security Champions.
  • Process – Describes the relative maturity across internal processes to address software security.
  • Technology – Covers the selection, procurement, and use of software security and DevOps tools to help operate and report on the effectiveness of  a software security program.

For each of the major categories, the Purple Book Community’s S3M2 model consists of five maturity levels, each representing a higher degree of software security practices. These levels are as follows:

1. Level 1: Reactive/Ad-hoc 

  • At this level, the software security practices within the organization are reactive and ad-hoc. There is limited – if any --  awareness and attention given to security issues. Security measures are implemented only in response to incidents or as a temporary fix. There is no defined strategy or consistent approach to software security.

2. Level 2: Proactive 

  • At Level 2, the organization transitions towards a proactive approach to software security. There is an acknowledgment of the importance of security, and efforts are made to implement preventive measures. Security controls and processes are integrated into the software development lifecycle (SDLC), and the organization takes steps to address common vulnerabilities and establish secure coding practices.

3. Level 3: Managed 

  • In Level 3, the organization establishes a managed software security program. There is the beginnings of strategy and policies in place for software security. Roles and responsibilities are defined, and security activities are integrated into the SDLC. The organization follows established standards, guidelines, and best practices for secure software development.

4. Level 4: Optimized 

  • At Level 4, the organization focuses on optimizing its software security practices. There is a data-driven approach, with metrics and measurements used to evaluate the effectiveness of security controls. Lessons learned from previous incidents and experiences are used to continuously improve security practices. The organization strives for efficiency, automation, and streamlining of security processes.

5. Level 5: Dynamic 

  • Level 5 represents the highest level of maturity in the Purple Book Community model. At this stage, the organization has a dynamic and advanced software security program. There is a culture of innovation, collaboration, and continuous learning. The organization actively engages with the broader software security community, shares knowledge, and adopts emerging technologies and methodologies. It strives for excellence in software security by anticipating and adapting to evolving threats and industry trends.

The Purple Book Community's Scalable Software Security Maturity Model provides organizations with an ability to develop a custom roadmap to enhance their software security practices. It encourages a progression from reactive and ad-hoc measures towards a proactive, managed, optimized, and dynamic approach to ensure the resilience and security of software systems.

By using S3M2, organizations can assess their current software security maturity, identify gaps and areas for improvement, and develop a roadmap to advance their security practices. It provides a structured approach that enables organizations to incrementally enhance their software security capabilities while fostering collaboration within the broader community.