Approach a security development lifecycle (SDL) as a continuous, risk-driven way to build, release, and operate software—not as a tool you install or a final security test. Assign owners, define security and privacy requirements, model threats during design, build and verify against those requirements, and keep monitoring and incident response connected to the next development cycle.
What does an SDL include?
Microsoft describes five core SDL phases: requirements, design, implementation, verification, and release. Training supports work across those phases, while response continues after release. This structure is a useful starting point, not a requirement that every organization copy Microsoft’s internal process. Controls and approval thresholds should fit the system’s risks, architecture, delivery method, and obligations.
An SDL is a governance and engineering practice, not a single software package. NIST’s Secure Software Development Framework (SSDF), Version 1.1, published in 2022, offers a high-level set of practices that can be integrated into an existing software development lifecycle. NIST notes that few SDLC models address software security in detail, so security practices often need to be added to the model an organization already uses.
How do you put an SDL in place?
Start with a small set of requirements and controls that apply to the product, assign people to own them, and make evidence of completion part of normal development work. Revisit the controls as the product, threats, and operating environment change.
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1. Set scope, ownership, and training
Identify the products, services, teams, data, and delivery processes the SDL covers. Name accountable security owners and define how developers raise concerns, who can accept or escalate risk, and who can block a release. Give people training suited to their roles: developers need practical secure-coding guidance, while architects, testers, product owners, and incident responders need guidance relevant to their decisions.
Microsoft includes general and role-specific security and privacy training in its SDL. Training is useful when it informs specific responsibilities and recurring work, rather than serving only as a one-time compliance checkbox.
2. Define security and privacy requirements
Translate the product’s actual exposure into requirements. Consider the sensitivity of the data handled, actions that could cause harm, untrusted inputs, external interfaces, known threats, applicable regulations and procurement obligations, industry practices, and lessons from prior incidents. Requirements might address access control, data handling, logging, availability, privacy, or how vulnerabilities are reported and fixed.
Track requirements alongside product work so that each has an owner and a way to verify it. Treat them as living requirements: a new feature, integration, data type, or threat can change what the product needs. Establish security quality bars and key performance indicators (KPIs) that show whether required work is being completed; define measures that fit your process instead of relying on an unsupported universal benchmark.
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3. Design the system and model threats
Map system components, data flows, external dependencies, and trust boundaries. Use that model to identify, categorize, and rank threats. For each unacceptable risk, record a mitigation as a design requirement, assign an owner, and track it through implementation and verification. Update the model when architecture or functionality changes, and review it for completeness before release.
Microsoft’s SDL describes its Threat Modeling Tool as a way to communicate security design, analyze designs using a proven methodology, and manage mitigations. The tool is one option; the essential practice is to make threats and mitigation decisions understandable, reviewable, and connected to engineering work.
4. Implement securely
Give developers approved tools and secure-coding guidance, and use established cryptography standards rather than ad hoc designs. Protect sensitive data in storage and transit where appropriate to the system’s risks and requirements. Microsoft lists encrypting data everywhere as an SDL practice; teams should translate that principle into explicit, testable requirements for their own data flows and architecture.
Control third-party components, including open-source dependencies. Maintain an inventory, review supply-chain risks, and define how components are selected, updated, and addressed when vulnerabilities are found. Include configuration safeguards so that secure defaults are not lost as software is deployed or operated.
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Use more than one verification method because each finds different kinds of problems. Define which checks apply to each product or change, who reviews results, and what must be fixed or formally resolved before approval.
- Independent manual review: Have a reviewer examine security-sensitive design or code, particularly where automated checks cannot establish whether the logic is safe.
- Static analysis security testing (SAST): Analyze source code or related artifacts for potential defects during development.
- Secret scanning: Check for exposed credentials or other secrets before they reach a repository or release.
- Dynamic analysis security testing (DAST): Test a running application for security issues that may not be evident from source analysis alone.
- Security testing and penetration testing: Test the product against relevant threats. Use penetration testing where appropriate to find issues that other methods may miss.
Record findings, owners, remediation, and disposition. A scan that runs but whose results are not reviewed or acted on is not an effective release control.
6. Gate and document the release
Before release, complete the required security and privacy reviews, confirm that security requirements and threat mitigations have been addressed, and resolve findings according to the organization’s defined risk process. Preserve evidence of reviews, test results, exceptions, and approvals so the release decision can be understood later. For higher-risk changes, consider staged or ring-based deployment so that issues can be detected before a broad rollout.
7. Operate, respond, and feed lessons back
After release, log and monitor the service, maintain an incident-response process, and remediate vulnerabilities. Establish how incidents are escalated and how relevant teams coordinate their response. Feed operational findings, vulnerabilities, and incident lessons into updated requirements, threat models, training, and future engineering work. This response phase is what keeps security from ending at deployment.
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How do you fit SDL into agile or DevOps?
Integrate security work into the same planning, development, review, and release flow the team already uses. Put requirements into the backlog, revisit threat models when designs change, run automated checks in the development and delivery process, and assign people to review findings. Define release gates in advance so teams know what must pass, what evidence to retain, and how exceptions are handled.
Microsoft describes its SDL as applicable from waterfall to modern DevOps and characterizes it as an approach for integrating security into DevOps processes. That does not mean every team needs identical gates or tooling. A useful SDL makes security work repeatable without assuming that a particular development methodology or product stack is universal.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.How should you choose or compare an SDL approach?
When comparing Microsoft SDL, NIST SSDF, or an internal DevSecOps process, compare how each approach fits your needs rather than treating the names as interchangeable certifications or tools.
- Lifecycle coverage: Does it cover requirements through release and operational response?
- Required gates: Does it define mandatory checks and approvals, or provide practices for your organization to adapt?
- Design depth: Does it require threat modeling and design review at a level suitable for your systems?
- Automation and evidence: Can the process run with your tools and preserve useful review and release records?
- Dependencies: Are third-party components and supply-chain risks addressed?
- Delivery fit: Can the controls work with your agile or DevOps cadence without weakening necessary safeguards?
- External obligations: Can you map practices to relevant regulatory, customer, or procurement requirements?
- Accountability and learning: Are owners, measures, and incident feedback clearly defined?
NIST SSDF is a high-level practice set intended to integrate with existing SDLC models; Microsoft SDL provides a lifecycle structure and named practices. An internal DevSecOps process can also be suitable if it makes ownership, controls, evidence, and response clear. The organization still needs to choose its lifecycle, controls, and thresholds.
What should be in an SDL’s minimum practice set?
Microsoft’s SDL FAQ names twelve practices. They can be used as a coverage check, adapted to the product and its risks:
- Provide security and privacy training.
- Define security requirements.
- Define security quality bars and KPIs.
- Use threat modeling.
- Establish design requirements.
- Encrypt data everywhere, translated into architecture-appropriate requirements.
- Use secure third-party components.
- Use approved tools.
- Perform static analysis security testing (SAST).
- Perform dynamic analysis security testing (DAST).
- Perform penetration testing.
- Establish a standard incident-response process.
The list is not a substitute for risk analysis: teams still need to decide how each practice applies, how results are assessed, and what evidence supports release decisions.
What does SDL adoption establish—and what does it not?
A well-defined SDL establishes repeatable responsibilities and security work across development and operation. It does not by itself guarantee that software is free of vulnerabilities, nor does a named framework determine a universal security threshold. Microsoft has not published a universal current percentage reduction in vulnerabilities or cost savings that can be attributed to SDL adoption. Set measures that reflect your own process and use them to identify gaps and improve controls.
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