What is the Secure Development Lifecycle (SDL)?

Key Steps of the Secure Development Lifecycle

The SDL is built on several key steps. They make sure that security is part of every stage of development.

Requirements

In this phase, you set the security requirements. That way, everyone involved shares the same view of the security measures that are needed. If you think about security from the very start, you can deal with problems before they arise.

Design

In the design phase, you plan the software architecture with security in mind. Threat models show where attackers could strike. They also help you plan the right countermeasures.

Writing the code

When you write the code, use secure coding techniques and review the code on a regular basis. This makes flaws less likely. Such flaws would be costly to fix later on.

Testing

In the testing phase, you run thorough security tests. These include penetration tests, static and dynamic code analysis and fuzz testing, among other things. The goal is software that holds up against attacks.

Release and upkeep

Once the software is released, you must ship security updates and patches on a regular basis. You also need to keep watching the system for new flaws.

Benefits of a Secure Development Lifecycle

An SDL has many benefits:

• Lower security risks: When you find and fix flaws early, the risk of security breaches drops a lot.
• Lower costs: Building security into development avoids costly defects. Later in the maintenance cycle, these defects can get very expensive.
• Customer trust: A secure software product builds customer trust and improves the brand image.

Challenges in Introducing an SDL

An SDL has clear benefits, but it also brings some challenges:

• Pushback from developers: Security practices can add to the work of developers. Some of them may push back.
• Consistency: To work, SDL practices must be applied the same way across all projects and teams.
• Ongoing training: Threats keep changing. So you need to keep training people and adapting your security practices.

Best Practices for the Secure Development Lifecycle

To bring in an SDL with success, you need a clear plan. These measures have worked well:

• Security requirements and threat modeling: Set security requirements early and do threat modeling for new features
• Secure coding rules and training: Binding coding rules and regular training for development teams
• Automated security testing: Add SAST, DAST and checks of third-party dependencies to the CI/CD pipeline
• Security gates before release: Fix critical findings before release, or accept them on purpose as a known risk
• Handling flaws in operation: A clear process to report, rate and fix flaws after release

Step by step

Bring in an SDL one step at a time:

1. Where you stand: Review the security measures already in your development process
2. Gap analysis: Find the areas that need to improve
3. Pilot project: Try it out with one selected development team
4. Rollout: Extend it to all development projects bit by bit
5. Monitoring: Keep watching the results and keep improving

Getting the team on board

These ways have worked well to overcome pushback:

• Open talk about why the SDL is needed and what it brings
• Hands-on training for developers
• Security champions in each team who people can turn to
• Start with high-risk projects that show results quickly

Measuring Success and KPIs

You should be able to measure the success of an SDL. Good metrics are:

• Number of flaws, split by the phase in which they were found
• Average time it takes to fix a flaw
• Share of projects with threat modeling and automated security testing
• Number of security findings after release, for example from penetration tests

Future Trends

• DevSecOps: More and more security checks are automated and run in CI/CD pipelines
• Software supply chain security: It is getting more important to secure open source dependencies and build processes, for example with software bills of materials (SBOM)
• AI in development: AI-assisted code analysis helps find flaws. But you must review AI-written code just as closely as code written by hand
• Post-quantum cryptography: Build apps so that you can swap out their crypto algorithms

Your Next Step

An SDL is an investment in the security and quality of your software. Our experts help you build an SDL that fits the way you develop.

Get started today:

• 📞 Free consultation: Book a talk with no strings attached
• 📋 Security assessment: Have the security of your development process checked
• 🎯 Tailored solution: We work out an SDL strategy just for you
• 🚀 Implementation: Rollout to your development teams, with ongoing support

Contact us today and take the first step toward a more secure digital future.