What is the SDLC?

The Software Development Lifecycle (SDLC) is the structured process organizations follow to plan, design, build, test, deploy, and maintain software. It provides a repeatable framework that helps teams deliver software on time, within scope, and with acceptable quality.

The Phases of the SDLC

1. Planning: Define the scope, goals, timeline, and resources. Identify stakeholders and constraints.
2. Requirements analysis: Document what the software must do — functional and non-functional requirements.
3. System design: Translate requirements into architecture, data models, interfaces, and component design.
4. Implementation: Write the code that fulfills the design.
5. Testing: Verify that the implementation meets requirements and is free from defects.
6. Deployment: Release the software to production.
7. Maintenance: Monitor, fix bugs, apply patches, and extend the software over its operational life.

SDLC Models

Why the SDLC Matters for Security

The SDLC matters for security because the phase in which a vulnerability is introduced determines how hard it is to remove. Vulnerabilities introduced in the requirements phase (missing security requirements) propagate through every subsequent phase. Vulnerabilities introduced in implementation are confined to the code, but may be replicated across many features if the root cause is systemic. Each phase is both an opportunity to introduce vulnerabilities and an opportunity to catch them.

Security in Each SDLC Phase

• Planning: Define security objectives. Identify regulatory requirements. Budget for security activities.
• Requirements: Write security requirements alongside functional ones. Define what "secure" means for this feature.
• Design: Conduct threat modeling. Review architecture for security anti-patterns. Define trust boundaries.
• Implementation: Apply secure coding standards. Use SAST and dependency scanning in CI.
• Testing: Run DAST against staging. Conduct penetration testing for high-risk applications.
• Deployment: Verify secrets management. Review production configurations. Enable runtime monitoring.
• Maintenance: Apply security patches promptly. Monitor for emerging vulnerabilities in dependencies.

SDLC and Autonomous Code Governance

Autonomous code governance integrates with the SDLC at the implementation and maintenance phases, where the greatest volume of code changes occur. Platforms like Hydra provide continuous security and quality analysis across every phase of ongoing development, ensuring that the security controls established in design and requirements are actually enforced in the code that ships. The result is an SDLC where security is not a periodic gate but a continuous property of the development process.