At what stage of the applications development process should the security department become involved?

Involving security prior to implementation is too late, as fundamental architectural security flaws may already be integrated into the design, making them expensive or impossible to remediate.

Involving security prior to systems testing means security is only considered after the design and most development phases are complete, leading to reactive security measures rather than proactive ones.

Involving security during unit testing is even later, focusing only on individual component vulnerabilities rather than the holistic security design of the entire application.

Involving the security department during the requirements development phase ensures that security is considered from the very beginning of the Software Development Lifecycle (SDLC). This 'Shift Left' approach allows for the definition of security requirements, integration of security considerations into the design, and ultimately leads to building security into the application rather than trying to add it on later, which is more effective and less costly.