7 SDLC methodologies that every Application Security Engineer should know
Over the years, the software development life cycle (SDLC) has been reintroduced with robust models adopted by security development teams across the globe. Each of these methodologies has advantages as well as disadvantages. Organizations are free to choose one that best suits their needs.
SDLC is a standard process of designing, developing, testing, and maintaining software. It focuses on developing cost-effective software within the best time possible. The software development team follows the chosen model for developing high-quality software.
For that, the team members must possess the required skills to develop software using secure SDLC. They should also be well-versed with various secure coding practices like input validation, cryptography, session management, and several others.
While making a choice, consider that different models offer a specific degree of flexibility. Although all these models follow different procedures, the goal is to provide high-quality software that is cost-effective within the best time possible.
Secure SDLC should be considered an industry-standard approach to deliver secure software. It can be divided into six phases to ensure the incorporation of security elements in the entire software development journey.
Common SDLC Models
Here are the most common SDLC models that every software security engineer should know:
1. Waterfall Software Development Life Cycle
This is a traditional approach that is falling out of favor because of its rigid nature. The model demands all system requirements ahead of time, while customer interaction is possible in the beginning phase only. Several experts claim that the waterfall model was never supposed to be used for developing software.
But there are those who appreciate the straightforward appeal of the model. It is a step-by-step approach with no turning back. The successive phase requires the information gathered in the preceding one.
Pros of Waterfall SDLC | Cons of Waterfall SDLC |
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2. Iterative Software Development Life Cycle
Unlike the stringent stepwise waterfall model, the iterative methodology begins by defining a subset of software requirements. Throughout the development process, the project iteratively evolves until the final system is implemented and successfully deployed. An iterative software development life cycle never starts with complete documentation of system requirements; it enhances with each phase.
Pros of Iterative SDLC | Cons of Iterative SDLC |
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3. Spiral Software Development Life Cycle
It is a combined idea of iterative and waterfall models with a major focus on risk analysis. Each phase in this model starts with a design goal and ends with the client approving the outcome of the phase.
As per this approach, the software development team begins with the pre-defined subset of software requirements and drifts through all the development phases with those sets of requirements. For every additional requirement, the team needs to add extra functionality in every spiraling phase until the software enters the production phase.
Pros of Spiral SDLC | Cons of Spiral SDLC |
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4. V-Model Software Development Life Cycle
The V-Model SDLC is also known as the Verification and Validation model. The processes occur sequentially in a V-shape. It is an extended form of Waterfall model with each development stage associated with a testing phase. The V-Model is a highly disciplined model, and as it is similar to the Waterfall model, the development team needs to complete each phase successfully before jumping onto another.
Pros of V-Model SDLC | Cons of V-Model SDLC |
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5. Agile Software Development Life Cycle
It is a combination of iterative and incremental SDLC models, but it concentrates on process adaptability and customer satisfaction. To fulfill the second objective, the model aims to achieve quick product delivery. Under this model, the product is divided into small incremental builds. All these builds go through iterative processes. The time required to complete an iteration is about 1 to 3 weeks.
Pros of Agile SDLC | Cons of Agile SDLC |
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6. Prototyping Software Development Life Cycle
The design team aims to produce an early model of the project with limited functionalities. The prototype does not contain the complete functionality or go through harsh testing; it just gives an overview to the clients about what to expect. Their response or feedback helps in the betterment of the developing software. The reason behind its increasing popularity is the understanding of customer requirements at the initial stage of software development.
Pros of Prototyping SDLC | Cons of Prototyping SDLC |
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7. RAD Software Development Life Cycle
The RAD (Rapid Application Development) methodology consists of prototype and iterative models without any specific plan. Under this model, the code writing process is included in the software development plan. The client requirements are gathered at various stages of the software development life cycle, including early prototype testing, reuse of the components of the prototype, or through workshops. The model allows for continuous integration at a rapid delivery pace.
Pros of RAD SDLC | Cons of RAD SDLC |
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Employ a Certified Application Security Engineer (CASE) professional who can choose a suitable SDLC model depending on the requirements of the project. The CASE program not only imparts comprehensive theoretical knowledge but ensures that the attendee gains all the required technical skills that could be put to immediate use. After completing the course, the professional is well-versed with the secure software development process and, as part of other responsibilities, can incorporate input validation techniques, defense coding practices, authentications, authorizations, and other techniques in the SDLC model.