What Is the SSDLC? A Guide to Secure Development

Updated: 26 June, 2025

11 June, 2025

Most security issues in software stem from one simple problem: teams try to fix them too late. The Secure Software Development Lifecycle (SSDLC) changes that by bringing security into each phase of development, not just the end.

In this article, we explain what the SSDLC is, why it matters, and how to make it work in practice using clear steps and proven frameworks.

Key takeaways

• The Secure Software Development Lifecycle (SSDLC) is a practical approach to embedding security into every phase of software development.

• Implementing the SSDLC helps teams reduce risk, improve software quality, and address vulnerabilities earlier and more effectively.

• The SSDLC includes seven key phases, from planning and analysis to maintenance, each requiring tailored security practices.

• OWASP SAMM offers a structured way to implement the SSDLC and is widely adopted by the security community.

• Supporting functions like governance and operations, while outside the SSDLC itself, help sustain secure development over time.

• SAMMY helps teams understand where they are, plan improvements, and demonstrate those improvements with clarity.

Listen to the summary of this article on The AppSec Management Podcast:

What is the SSDLC?

The term SSDLC stands for Secure Software Development Lifecycle. It builds on the familiar concept of the SDLC, which refers to the process of developing software, from the initial idea to design, development, testing, deployment, and maintenance.

In an ideal world, security would already be part of each of those steps. It is a quality attribute, like performance or reliability, and should be treated the same way. But in practice, security is often handled separately, introduced too late, or added as a final check before release. That is why the industry has adopted the term SSDLC, to emphasize the need to build security into the development lifecycle from the beginning.

In many teams today, security is still treated as an afterthought. The focus is on delivering features, with security addressed through penetration testing right before deployment. Patching and issue tracking happen later, often without a clear connection to how the software was built. While these activities matter, they are reactive and can leave critical risks undetected until they are much harder to fix.

The SSDLC offers a different approach. It is a structured way of building software that integrates security into the core activities of design, development, and testing. It encourages teams to identify and manage security risks throughout the entire lifecycle, using both proactive and preventative measures.

The SSDLC is not a fixed framework. It is a principle that can be applied using models like OWASP SAMM, Microsoft SDL, or NIST SSDF, each offering practical guidance for implementing security in development workflows.

Who should implement the SSDLC?

Any team involved in building or maintaining software can benefit from the SSDLC. This includes product developers, DevOps engineers, and teams working with internal or external codebases.

Smaller teams may begin with a simpler approach, but core SSDLC practices such as security requirements and threat modeling. For organizations in regulated industries or handling sensitive data, adopting the SSDLC is critical.

Security is everyone’s responsibility. The SSDLC helps make that responsibility part of everyday development.

What are the phases of the SSDLC?

The Secure Software Development Lifecycle (SSDLC) introduces security at every stage of building and maintaining software. The process is typically structured around several key phases that typically involve different sets of stakeholders.

1. Planning and analysis

Every software development process starts with understanding why the system is being built and what it needs to do. This phase defines the scope, objectives, and core requirements of the project. A secure approach means addressing security not only in the technical details later on, but also at this early stage.

A true SSDLC makes security part of the why and the what. This is done by identifying potential risks and translating them into security requirements. Doing so builds shared awareness across the team and ensures that risk is considered from the start, not just during implementation.

2. Design

Architecture decisions made in this phase shape how security will function. The focus is on choosing secure patterns, defining trust boundaries, and ensuring that designs can handle the threats identified earlier. This is also the right time to document how the system will enforce security controls.

3. Test planning

Security testing should be planned alongside functional testing, not treated as a separate activity. The starting point is the set of security requirements defined earlier in the process. Ideally, those requirements are mapped directly to unit and functional tests.

When that is not feasible, end-to-end acceptance tests can be used to validate critical controls. Planning these tests early helps avoid coverage gaps and ensures results are interpreted correctly.

4. Implementation

This is the phase where the software is written. Developers focus on applying secure coding practices, using safe defaults, and avoiding common security mistakes. While they use third-party components, managing and vetting those components is typically handled by governance or platform teams.

The goal during implementation is to write code that is maintainable and secure. This includes reviewing code, validating inputs, and following practices that reduce the risk of introducing vulnerabilities.

5. Testing

In this phase, security tests are written and executed. Ideally, they are part of the same regression test sets used for functional testing. These tests are based on the security requirements defined earlier, and they help ensure that critical controls behave as expected.

In more mature development processes, tests are written once and automatically run as part of the CI pipeline. In less mature environments, testing may still be manual and ad hoc. Security automation tools, such as static and dynamic analysis, can help fill gaps by performing additional checks, but they do not replace the need for custom tests that reflect the application’s specific risks.

All findings should be tracked and resolved through a clear process that supports accountability and long-term improvement.

6. Deployment

Deployment is the point where code moves into production, but it should not be the moment when security is introduced. By this stage, the software should already be tested and approved. The focus now is on making sure the deployment process itself does not create new risks.

This includes verifying that infrastructure and environment configurations are secure, secrets are handled correctly, and monitoring is in place. Mature teams rely on automated pipelines to enforce consistency and prevent accidental changes during release.

A secure deployment is repeatable and predictable. It should follow the same process every time, without introducing surprises.

7. Maintenance

Security does not end at deployment. Once the system is live, it must be continuously monitored and maintained to remain secure over time.

This phase includes incident detection and response, patching of vulnerabilities, and updating components as threats evolve. Monitoring tools should be in place to alert teams to suspicious behavior or system anomalies. When incidents do occur, clear response procedures help reduce impact and recover quickly.

Maintenance also includes proactive tasks. These range from reviewing logs and system health to auditing access controls and refreshing outdated dependencies. As new risks emerge and the system evolves, security controls must be reviewed and adjusted to stay effective.

A well-maintained system is not only more secure, it is also more resilient and easier to operate in the long run.

How to implement the SSDLC?

Putting the SSDLC into practice means integrating security into every stage of the software lifecycle. But in large organizations, moving from awareness to action is often the hardest part. Even when teams agree that secure development is important, aligning priorities, changing workflows, and building new habits takes time. Progress can be slow, especially across multiple business units or distributed development teams.

This is where OWASP SAMM becomes especially valuable. It provides not only structure and clarity, but also a maturity-based approach that supports iterative improvement. Rather than requiring perfection from the start, SAMM helps teams take manageable steps forward, build on what works, and scale gradually across the organization.

SAMM is a flagship project of the OWASP Foundation, the organization that leads the way in secure software guidance. Thousands of security professionals, developers, and organizations have contributed to and adopted SAMM, making it one of the most trusted models in the industry.

What business functions in SAMM cover the SSDLC?

SAMM translates the principles of the SSDLC into concrete security practices that teams can adopt across the core development business  functions: Design, Implementation, and Verification. Each business function is broken down into three security practices, each with two streams and clearly defined maturity levels. This gives teams a way to start simple and improve progressively.

For example:

• During design, SAMM requires teams to perform threat assessments and define meaningful security requirements as part of a structured, risk-driven approach.
• During implementation, SAMM prescribes secure build practices, proper dependency management, and the consistent use of coding standards.
• During verification, it provides structured guidance for testing against security goals and risk models.

SAMM is intentionally flexible and agnostic. It is not tied to any specific technology, team size, or development methodology. This makes it well suited to a wide range of organizations, from startups to global enterprises. While it provides clear structure and guidance, it allows each team to apply practices in a way that fits their context, promoting measurable and sustainable improvement over time.

In addition to the core development activities, SAMM also includes Governance and Operations functions. These cover areas such as policy definition, training, incident response, and environment hardening. While not strictly part of the SSDLC, these practices provide essential support and help ensure that secure development is backed by clear strategy and operational readiness.

For these reasons, SAMM is more than just compatible with the SSDLC. It represents the most complete and community-backed definition of what an OWASP-aligned SSDLC should look like in practice.

If you want to explore this idea in more depth, we recommend reading our dedicated article on how OWASP SAMM serves as OWASP’s recommended SSDLC.

Case study: Applying the SSDLC with OWASP SAMM at Zebra Technologies

Zebra Technologies, a Fortune 500 enterprise with multiple business units and development teams, needed a structured way to strengthen application security across the organization. Rather than creating a new process from scratch, they chose to adopt OWASP SAMM to guide the implementation of their Secure Software Development Lifecycle.

The initiative began with internal self-assessments. Each team evaluated their maturity across key security practices in the design, implementation, and verification functions. These assessments highlighted strengths, revealed gaps, and provided a baseline for improvement.

From there, teams set risk-aligned improvement targets. Each group worked toward goals that matched their context, such as better threat modeling practices or stronger security testing coverage. SAMM’s maturity levels made it possible to track progress incrementally.

To encourage adoption and engagement, Zebra introduced a gamified approach. Teams compared SAMM scores and shared improvement stories, creating friendly competition and cross-team learning.

Most importantly, the results went beyond compliance. Teams that improved their SAMM maturity also reported broader gains in quality, such as fewer security defects in production and faster response to incidents. This helped demonstrate that secure development is not a trade-off, but a catalyst for better software overall.

For a detailed look at how this was achieved, read our full case study: OWASP SDLC guidance: A story of OWASP SAMM implementation

Tooling to implement the SSDLC

Bringing the SSDLC to life is easier when teams have the right tools to support their process. OWASP SAMM offers the structure, but applying it in a consistent and measurable way across multiple teams and projects requires more.

That is where SAMMY comes in.

SAMMY is Codific’s platform designed to help organizations implement the SSDLC using OWASP SAMM. It allows you to assess maturity across the 15 security practices, identify gaps, and build structured improvement plans. SAMMY makes it easier to collaborate across teams and keep everyone aligned on what matters most.

The platform includes:

• A built-in assessment engine based on the official SAMM model

• Visual dashboards to track maturity, risk, and progress

• Team-specific improvement planning with clear ownership

• Support for multi-project or multi-team environments

SAMMY is free to use and can be set up in minutes. For teams serious about improving how they build secure software, it is a practical next step that bridges strategy and execution.

Conclusion

The SSDLC is not just a security ideal, it is a practical necessity. As systems grow more complex and threats more advanced, secure development must be built into how we work, not added as an afterthought.

OWASP SAMM provides a clear and flexible way to implement the SSDLC across real-world teams and projects. It brings structure without being rigid, and it makes continuous improvement both possible and measurable.

Whether you are just getting started or looking to improve an existing process, combining SSDLC principles with the guidance of OWASP SAMM can help your team move forward with clarity and purpose.

To support your journey, tools like SAMMY are available to help you apply SAMM in a structured and consistent way. It is free to use and designed to help teams like yours take the next step toward building software that is secure by design.