SA-5(5) — Source Code

In some cases, you may need access to the source code of security-relevant components to verify that security controls are properly implemented. This applies primarily to custom-developed or high-assurance systems.

Example 1: For custom-developed applications, maintain the source code in a version-controlled repository (Git) with access restricted to authorized developers and security reviewers. Conduct code reviews of security-relevant modules (authentication, authorization, cryptography, input validation) before each release.

Example 2: For vendor-provided software where source code access is needed, include escrow provisions in contracts so that source code is available for security review or if the vendor goes out of business. For open-source components, review the relevant source code and track the project's security posture.