Secure SDLC: Building Security In
Learn how to integrate security throughout the software development lifecycle. Essential CISA exam knowledge for IS acquisition and development.
What Is Secure SDLC?
A secure software development lifecycle (Secure SDLC or SSDLC) integrates security activities into every phase of software development rather than treating security as an afterthought. For CISA candidates, understanding Secure SDLC is critical because it represents the most effective approach to reducing software vulnerabilities and is a frequent topic in the IS acquisition domain.
Security Activities by SDLC Phase
Each phase of the SDLC should include specific security activities:
- Requirements phase: Define security requirements alongside functional requirements. Identify regulatory and compliance requirements that affect the application. Perform abuse case analysis to understand how the system might be misused.
- Design phase: Conduct threat modeling to identify potential threats and design countermeasures. Apply secure design principles including least privilege, defense in depth, and fail-safe defaults. Document the security architecture.
- Implementation phase: Follow secure coding standards to prevent common vulnerabilities. Use static analysis tools to identify security flaws in source code. Conduct peer code reviews with security focus.
- Testing phase: Perform security testing including static application security testing (SAST), dynamic application security testing (DAST), and penetration testing. Verify that security requirements are met through specific test cases.
- Deployment phase: Perform security configuration reviews. Verify that production environments match security baselines. Conduct final security assessments before go-live.
- Maintenance phase: Monitor for new vulnerabilities. Apply security patches promptly. Conduct periodic security assessments and penetration tests.
Secure SDLC Frameworks
Several frameworks guide Secure SDLC implementation:
- Microsoft SDL: A comprehensive framework that defines security practices for each development phase, including training, requirements, design, implementation, verification, release, and response.
- OWASP SAMM: The Software Assurance Maturity Model provides a measurable way to analyze and improve software security posture across governance, design, implementation, and verification.
- BSIMM: The Building Security In Maturity Model is a data-driven framework based on observations of real-world software security initiatives.
Key Secure Development Practices
Core practices that support Secure SDLC include developer security training to build awareness of common vulnerabilities and secure coding techniques, threat modeling workshops during design, automated security testing integrated into CI/CD pipelines, security champions within development teams who promote security practices, and vulnerability management processes that track and remediate identified issues.
Auditing Secure SDLC
IS auditors should evaluate Secure SDLC practices by verifying that security requirements are documented and traceable, that threat modeling is performed for new applications, that secure coding standards are defined and followed, that security testing is adequate and timely, and that vulnerability remediation processes are effective.
CISA Exam Tips
For the CISA exam, understand the security activities appropriate to each SDLC phase and the principle that addressing security early in development is far less expensive than fixing vulnerabilities after deployment. Questions may present development scenarios and ask which security activity is most appropriate at a given phase.