What is the secure software development lifecycle?

Software development traditionally follows a linear path: plan, code, test, deploy. For decades, security only entered the equation during the testing phase—after thousands of lines of code were already written.

SSDLC challenges this traditional approach by embedding security into all phases of the software development lifecycle (SDLC) from day one. The SSDLC is often structured into nine phases: requirements, analysis, planning, design, development, documentation, testing, deployment and maintenance.

Teams begin by discussing security concerns alongside functional requirements while developers write secure code by using validated inputs and authentication standards. Testing runs continuously, not just before release, often through automated code reviews.

This “shift left” approach—moving security earlier in the development process—can help transform how organizations build software. Instead of asking “Is this secure?” during testing, teams ask “How do we make this secure?” before writing the first line of code.

For example, consider a banking application. Traditional development might discover an SQL injection vulnerability during prelaunch testing, requiring developers to rewrite database interactions across hundreds of files. With an SSDLC, teams are far more likely to detect that vulnerability earlier because security checks run throughout design, build and test.

Recent data helps show why this proactive approach matters. According to a recent supply chain security study, software supply chain attacks rose 1300% in just three years.¹

SSDLC can help protect organizations against these cyberattacks and others by detecting vulnerabilities earlier—when fixes are simplest and least costly. It can also help maintain compliance with regulations such as the General Data Protection Regulation (GDPR) and Health Insurance Portability and Accountability Act (HIPAA).

There are generally nine SSDLC phases, which closely follow the SDLC model, except that every phase also incorporates security considerations:

• Requirements
• Analysis
• Planning
• Design
• Development
• Documentation
• Testing
• Deployment
• Maintenance

Teams discuss the capabilities of the finished software, defining security requirements alongside functional requirements from day one—for example, implementing encryption for sensitive data fields and establishing role-based access controls (RBAC). This discussion involves reviewing potential security risks plus compliance requirements such as GDPR’s data protection standards.

Organizations quantify potential vulnerabilities and map their threat landscape, planning for worst-case scenarios rather than best-case assumptions. For instance, a healthcare app might analyze the risks of patient data breaches, ransomware attacks and insider threats—planning responses for each.

Security teams and stakeholders establish roles, allocate resources and define acceptable baselines based on potential business impact. This planning enables prioritization of high-risk vulnerabilities while still meeting development deadlines. It also enables them to budget for security tools and training before coding begins.

The design phase involves threat modeling—a systematic analysis of potential security vulnerabilities in the planned architecture. This practice helps ensure that secure design is built into the system blueprint—from the best platform to the ideal UI—rather than added as a costly retrofit.

Developers apply secure coding practices based on secure coding standards established by organizations such as the Open Web Application Security Project (OWASP). These standards can include validating all inputs, implementing authentication techniques, using proper API calls, scanning repositories and handling errors securely.

Developers often use integrated development environments (IDEs) with security plug-ins to help catch issues earlier.

Teams evaluate software dependencies to mitigate security risks, with security testing beginning during development. For example, a payment processing module would undergo security testing while being built, not after integration. 

Teams document security controls and processes for audits, compliance checks and security reviews, enabling rapid incident response and ongoing regulatory compliance.

Testing combines code reviews with security testing. Teams validate both functionality and security before deployment.

Testing includes static analysis—such as static application security testing (SAST)—to analyze source code without running the program, and dynamic application security testing (DAST) to test applications while running.

Advanced testing can include ethical hackers challenging the code, penetration tests validating data security and simulations that exercise APIs. Software composition analysis (SCA) can also be run in parallel to help identify vulnerable open source dependencies and licensing issues.

Teams secure the deployment environment—servers, configurations and middleware—before releasing software. This helps prevent vulnerabilities from being introduced through misconfigured infrastructure.

Many teams also collect software telemetry—metrics, logs and traces—to see how code behaves in real environments. OpenTelemetry (OTel) is an open-source project from the Cloud Native Computing Foundation (CNCF) that enables vendor-neutral collection and transport of metrics, logs and traces, helping ensure consistent signals across services, pipelines and environments.

Continuous monitoring can help detect threats and vulnerabilities early, enabling rapid remediation throughout the software lifecycle. This phase can be especially critical for preventing zero-day exploits and responding to newly discovered vulnerabilities.

Organizations typically begin the secure software development lifecycle with established frameworks: comprehensive methodologies that include security benchmarks, security best practices and risk assessment tools. Some of the most common frameworks include:

The National Institute of Standards and Technology provides government-backed practices and benchmarks specific to secure development, including the Secure Software Development Framework, NIST SP 800-218.

This framework helps organizations establish baseline security requirements across all development teams. Compared to other frameworks, it provides more prescriptive federal standards, often making it ideal for government contractors and regulated industries. Organizations working with federal agencies frequently must comply with NIST standards as a contractual requirement.

The Open Web Application Security Project (OWASP) offers an open framework: the Software Assurance Maturity Model (SAMM).

OWASP SAMM helps organizations assess existing software security practices and build iterative improvement programs that are tailored to their specific risk profiles. 

For this reason, it is often favored by organizations seeking flexible, maturity-based approaches rather than rigid compliance requirements. For instance, a startup can begin with basic security practices in critical areas such as authentication, then gradually expand to comprehensive security testing as the team and budget grow.

The OWASP DevSecOps Guideline details pipeline implementation with integrated security testing tools: SAST, DAST, SCA (software composition analysis), and IAST (interactive application security testing). Following this guideline can help make it easier to embed security testing into existing continuous integration and continuous delivery (CI/CD) pipelines without disrupting development workflows.

As a result, organizations seeking to automate security without slowing release cycles might favor the OWASP DevSecOps Guideline—such as fintech companies deploying updates daily while maintaining PCI DSS compliance.

Many organizations implement SSDLC through DevOps and DevSecOps practices, which automate security testing and integrate it into CI/CD pipelines—speeding development while maintaining security standards. Using DevSecOps techniques, development teams are responsible for application security in addition to secure design, building, operations and maintenance. To iterate quickly and avoid bottlenecks, they often use automation for security testing.

SLSA (‘salsa’) is a community framework—originally proposed by Google and now under the OpenSSF—for safeguarding software supply chains. 

Its guidelines help organizations prevent tampering, verify artifact integrity and automate verification of build processes and dependencies. Organizations that want to optimize for supply chain security and build provenance might implement SLSA to prove their software hasn’t been tampered with during the build process. For example, a software vendor that is distributing enterprise applications needs to prove to customers that their releases are authentic and untampered.

SSDLC can provide organizations with several critical benefits. 

SSDLC’s “shift left” approach helps organizations detect and fix vulnerabilities when they’re often the easiest and least expensive to address: during design and development rather than after deployment.

For instance, a design-phase review might find that a planned architecture would expose sensitive customer data through an unsecured API endpoint. Detecting this issue early enables more secure architecture from the start, avoiding the potential damage of a data breach and the costly retrofit of security controls.

Organizations can also see reduced costs when a breach occurs. According to the Cost of a Data Breach Report, a DevSecOps approach (including SSDLC) was the number-one factor in reducing data breach costs. Organizations that use this approach experienced USD 227,192 lower costs per data breach.

SSDLC can help prevent system downtime by identifying security issues before deployment, potentially avoiding emergency fixes and improving software stability. Threat modeling and detailed code reviews at all stages can also enhance this stability.

SSDLC helps protect the software supply chain, which includes all infrastructure and people who touch the code from development through the CI/CD pipeline to deployment. It combines risk management practices (such as threat modeling and dependency scanning) with cybersecurity controls (such as access restrictions and code signing) to prevent vulnerabilities across the entire lifecycle.

For instance, SSDLC can help organizations implement software bills of materials (SBOMs) to track all components and dependencies. This approach makes it easier to identify and remediate vulnerabilities when they’re discovered in third-party libraries.

SSDLC helps organizations maintain compliance by building security controls and documentation into each development phase. This process is critical for organizations that need to consistently meet industry-specific security standards such as General Data Protection Regulation (GDPR), the Health Insurance Portability and Accountability Act (HIPAA) and the California Consumer Privacy Act (CCPA). More reliable compliance can help ensure fewer legal issues and potential fines. 

When implementing SSDLC, development, operations and security teams must frequently work closely together to surface multiple viewpoints in software development. This necessary collaboration can help break down silos between departments and head off security issues that might become costly later.

Despite its many benefits, a few challenges can arise when organizations move to adopt SSDLC. 

Stakeholders who want faster time-to-market can often see security requirements as impediments to development speed. They might even request to defer security testing until later phases. 

While this approach can accelerate initial development, it often leads to costlier delays when vulnerabilities surface after deployment.

Skipping threat modeling during design, for instance, can leave critical attack paths exposed. Without systematic threat analysis, teams might miss security gaps in authorization systems, data access controls or third-party service integrations—vulnerabilities that become exponentially more expensive to fix in production.

As the threat landscape continues to evolve, development teams must maintain current security knowledge. Organizations without dedicated security expertise might need more training, specialized hires or external consultants to implement SSDLC effectively.

For example, developers new to secure coding might not know when to use static analysis tools or how to interpret their findings. Without proper training, these tools might flag critical vulnerabilities that go unaddressed, or generate false positives that waste development time. Even experienced developers often need ongoing education to stay current with emerging threats and security practices.

Complex software architectures with multiple integrations can sometimes require sophisticated security tools and processes, potentially increasing development time and costs. For instance, integrating IoT devices that use different data formats and communication protocols can create other attack surfaces that teams must secure.

Consider an encryption API implementation, where the API must operate with minimal access privileges while supporting various use cases. Some services might need encryption capabilities without decryption rights. This process can require careful planning around access controls, authentication and transport layer security (TLS), adding complexity around each integration point that teams must address without compromising security or functionality.