Software Development Life Cycle (SDLC)

What is the SDLC?

Definition of SDLC

The Software Development Life Cycle (SDLC) is a structured process that enables the production of high-quality, low-cost software, in the shortest possible production time. The goal of the SDLC is to produce superior software that meets and exceeds all customer expectations and demands. The SDLC defines and outlines a detailed plan with stages, or phases, that each encompass their own process and deliverables. Adherence to the SDLC enhances development speed and minimizes project risks and costs associated with alternative methods of production (i).

How was the SDLC created?

In the 1950s and 1960s, computer science progressed rapidly. This swift evolution sparked the beginnings of a production framework that eventually grew into the SDLC we know today.

Prior to the 1950s, computing was not elaborate enough to necessitate a detailed approach like the SDLC. As the complexity and scale of programming grew, the concept of structured programming emerged. Over time, structured programming demanded more tactical development models, thus sparking the beginnings of the SDLC (ii). 

Why is the SDLC important? What are the advantages of implementing the SDLC?

• It provides a standardized framework that defines activities and deliverables
• It aids in project planning, estimating, and scheduling
• It makes project tracking and control easier
• It increases visibility on all aspects of the life cycle to all stakeholders involved in the development process
• It increases the speed of development
• It improves client relations
• It decreases project risks
• It decreases project management expenses and the overall cost of production

The role of security in the SDLC

The initial concept and creation of the SDLC only addressed security activities as a separate and singular task, performed as part of the testing phase. The shortcomings of this after-the-fact approach were the inevitably high number of vulnerabilities or bugs discovered too late in the process, or in certain cases, not discovered at all. Today, it is understood that security is critical to a successful SDLC, and that integrating security activities throughout the SDLC helps create more reliable software. By incorporating security practices and measures into the earlier phases of the SDLC, vulnerabilities are discovered and mitigated earlier, thereby minimizing overall time involved, and reducing costly fixes later in the life cycle.

This idea of ‘baking-in’ security provides a ‘Secure SDLC’- a concept widely recognized and adopted in the software industry today. A secure SDLC is achieved by conducting security assessments and practices during ALL phases of software development.

With modern application security testing tools, it is easy to integrate security throughout the SDLC. In keeping with the ‘secure SDLC’ concept, it is vital that security assurance activities such as penetration testing, threat modeling, code review, and architecture analysis are an integral part of development efforts. 

The primary advantages of pursuing a secure SDLC approach include

• More secure software as security is a continuous concern
• Awareness of security considerations by stakeholders
• Early detection of flaws in the system
• Cost reduction as a result of early detection and resolution of issues
• Overall reduction of intrinsic business risks for the organization

How does the SDLC work?

What are the SDLC stages/phases?

Planning phase

The planning phase encompasses all aspects of project and product management. This typically includes resource allocation, capacity planning, project scheduling, cost estimation, and provisioning.

During the planning phase, the development team collects input from stakeholders involved in the project; customers, sales, internal and external experts, and developers. This input is synthesized into a detailed definition of the requirements for creating the desired software. The team also determines what resources are required to satisfy the project requirements, and then infers the associated cost.

Expectations are clearly defined during this stage as well; the team determines not only what is desired in the software, but also what is NOT. The tangible deliverables produced from this phase include project plans, estimated costs, projected schedules, and procurement needs. 

Coding phase

The coding phase includes system design in an integrated development environment. It also includes static code analysis and code review for multiple types of devices.

Building Phase

The building phase takes the code requirements determined earlier and uses those to begin actually building the software.

Testing Phase

The phase entails the evaluation of the created software. The testing team evaluates the developed product(s) in order to assess whether they meet the requirements specified in the ‘planning’ phase. 

Assessments entail the performance of functional testing: unit testing, code quality testing, integration testing, system testing, security testing, performance testing and acceptance testing, as well as nonfunctional testing. If a defect is identified, developers are notified. Validated (actual) defects are resolved, and a new version of the software is produced.

The best method for ensuring that all tests are run regularly and reliably, is to implement automated testing. Continuous integration tools assist with this need.

Release Phase

The release phase involves the team packaging, managing and deploying releases across different environments.

Deploy Phase

In the deployment phase, the software is officially released into the production environment. 

Operate Phase

The operate phase entails the use of the software in the production environment.

Monitor Phase

In the monitor phase, various elements of the software are monitored. These could include the overall system performance, user experience, new security vulnerabilities, an analysis of bugs or errors in the system.

What does Synopsys Offer?

As shown above, security is critical to the SDLC. Synopsys enables you to add security testing to an existing development process, thereby streamlining security throughout the SDLC. Synopsys solutions help you manage security and quality risks comprehensively, across your organization and throughout the application life cycle.

Synopsys offers solutions for each phase of the SDLC.

Comprehensive Product and Service Offerings for your entire SDLC

Synopsys offers products  and services that can be integrated throughout your SDLC to help you build secure code, fast.

• Building Security In Maturity Model (BSIMM) - Measure and benchmark your software security program against other security programs and industry best practices.
• Maturity Action Plan (MAP) - Get recommendations establish or improve your software security stance.
• Software Testing Optimization - Help your team prioritize and create the right level of security testing. 
• Application Security Consulting Services - Tackle your most challenging security and risk management initiatives with on-demand help from experts.
• Security Training/eLearning - Synopsys offers a wide range of education solutions to address your needs; from understanding the basics of coding standards, to developing advanced skills to build secure code.

Strategic Product and Service Offerings for your Specific SDLC Needs

Architecture Risk Analysis - Improve your security stance and ensure that you have secure design practices in place by identifying flaws within your systems designs.

• For your planning phase activities

Threat Modeling - Bring your application design weaknesses to light by exploring potential hacker exploits. Spot design flaws that traditional testing methods and code reviews might overlook.

• For your planning phase activities

Coverity SAST - Analyze source code to find security vulnerabilities that make your organization’s applications susceptible to attack. Address security and quality defects in code while it is being developed, helping you accelerate development an increase overall security and quality.

• For your code and build phase activities

Seeker - Automate web security testing within your DevOps pipelines, using the industry’s first IAST solution with active verification and sensitive-date tracking for web-based applications. (IAST) uses dynamic testing (a.k.a. runtime testing) techniques to identify vulnerabilities in running web applications.

• For your test and release phase activities

Defensics - Identify defects and zero-day vulnerabilities in services and protocols. Defensics is a comprehensive, versatile, automated black box fuzzer that enables organizations to efficiently and effectively discover and remediate security weaknesses in software.

• For your test and release phase activities

Tinfoil Dynamic application security testing (DAST) - Dynamic analysis evaluates an application while executing it to uncover issues with its runtime behavior.

• For your deploy, operate, and monitor phase activities

Black Duck Software Composition Analysis - secure and manage open source risks in applications and containers. Black duck offers a comprehensive software composition analysis (SCA) solution for managing security, quality, and license compliance risk that comes from the use of open source and third-party code in applications and containers.

Black Duck offers support from the code phase of your SDLC through your monitor phase activities:

• Integrate Black Duck into bug and issue trackers to enable developers to track and manage open source issues found both in the test and release phases.
• Automated ticket creation related to policy violations and security alerts helps teams manage issues in the systems they already use to speed time to resolution and efficiently manage testing work.
• Teams can perform a final scan for open source security, license or operational issues before the application is deployed to production.
• Leverage advanced vulnerability remediation guidance, open source license information and policy controls to eliminate open source risk in applications and containers.
• Continuously monitor applications and containers in production for new open source vulnerabilities and alert teams where they work so they can patch issues quickly before a potential exploit occurs.
• Black Duck integrates directly into the developers IDE to flag potential issues in open source components as they code, and integrations into package managers and build tools automate the discovery of open source dependencies to ensure a complete and accurate open source bill of materials (BoM).

Managed Services - Synopsys Managed Application Security Testing offers the solution for applying AppSec testing effectively across your full application portfolio. Accelerate and scale application security testing with on-demand resources and expertise when you lack the resources or skills to achieve your risk management goals.

Managed Services offer support from the code phase of your SDLC through your monitor phase activities:

• Managed Dynamic Application Security Testing (DAST) - If your team lacks the resources for effective DAST testing, Synopsys Managed DAST allows you to analyze web applications at any time without the cost or complexity of in-house DAST.
• Managed Penetration Testing - Synopsys Managed Penetration Testing uses multiple testing tools and in-depth manual tests focusing on business logic to find and try to exploit vulnerabilities in running web applications or web services. 
• Managed SAST - Synopsys Managed SAST enables you to quickly and cost-effectively implement and scale static analysis to systematically find and eliminate security vulnerabilities found in source code. 

Penetration testing - Penetration testing analysis helps you find and fix exploitable vulnerabilities in your server-side applications and APIs. Reduce your risk of a breach by identifying and exploiting business-critical vulnerabilities, before hackers do.

• For your operate and monitor phase activities

Red Teaming - Ensure your network, physical, and social attack surfaces are secure. Vulnerabilities may seem small on their own, but when tied together in an attack path, they can cause severe damage. Our red team models how a real-world adversary might attack a system, and how that system would hold up under attack.

• For your operate and monitor phase activities

What are the SDLC models/methodologies?

Waterfall

Waterfall represents the oldest, simplest, and most structured methodology. Each phase depends on the outcome of the previous phase, and all phases run sequentially. This model provides discipline and gives a tangible output at the end of each phase. However, this model doesn’t work well when flexibility is a requirement. There is little room for change once a phase is deemed complete, as changes can affect the cost, delivery time, and quality of the software.

Agile

The agile methodology produces ongoing release cycles, each featuring small, incremental changes from the previous release. At each iteration, the product is tested. The agile model helps teams identify and address small issues in projects before they evolve into more significant problems. Teams can also engage business stakeholders and get their feedback throughout the development process.

Lean

The lean methodology for software development is inspired by lean manufacturing practices and principles. The lean principles encourage creating better flow in work processes and developing a continuous improvement culture. The seven lean principles are:

• Eliminate waste
• Amplify learning
• Make decisions as late as possible
• Deliver as fast as possible
• Empower your team
• Build integrity in
• Build holistically

Iterative

In the iterative process, each development cycle produces an incomplete but deployable version of the software. The first iteration implements a small set of the software requirements, and each subsequent version adds more requirements. The last iteration contains the complete requirement set.

Spiral

In the spiral development model, the development process is driven by the unique risk patterns of a project. The development team evaluates the project and determines which elements of the other process models to incorporate. 

V-Shaped

In the V-shaped model, verification phases and validation phases are run in parallel. Each verification phase is associated with a validation phase, and the model is run in a V-shape, where each phase of development has an associated phase of testing.

SDLC best practices

The most important best practice to implement into your SDLC is effective communication across the entire team. The more alignment, the greater the chances for success.

Signs of a well-implemented SDLC include:

• The successful deployment of a comprehensive application security program
• Code quality standards
• Effective collaboration across teams
• Streamlined workflows
• Cross-involvement of teams throughout the life cycle [iii]

SDLC common mistakes and challenges

There are several pitfalls that threaten to negatively impact an SDLC implementation. Perhaps the most problematic mistake is a failure to adequately account for and accommodate customer and stakeholder needs in the process. This results in a misunderstanding of system requirements, and inevitable disappointment with the end-product.

Additionally, the complexity of the SDLC often causes a project to derail or teams to lose sight of specifics and requirements. Without strict adherence to all aspects of the parameters and design plans, a project can easily miss the mark (iv).

The future of the SDLC

With the adoption of faster and newer development life cycles, organizations are moving away from older SDLC models (waterfall, for example). With ever-increasing demands for speed and agility in the development process, automation has played a key role.

Development and operations are merging into a DevOps capability, as the boundaries between disparate teams has been slowly dissolving in favor of a streamlined and synchronized approach to development.

Newer approaches to the SDLC have emerged as DevOps, a combination of philosophies and practices that increase an organization’s ability to deliver applications more quickly. As SDLC methods shift more toward a DevOps SDLC, consideration of the role security plays must also be addressed. Security is no longer a separate and compartmentalized step in the SDLC-in order to guarantee secure software, produced at the speed of DevOps, security is now being viewed as a critical component throughout the SDLC.

In coming years, no doubt, organizations will adopt not only a DevOps approach to their SDLC, but a more evolved DevOps methodology, where security is baked into the entirety of the SDLC. In order to guarantee the success of this modern software development model, an organization must be strategic in selecting tools that support and enhance this effort. As a proven leader in the application security field, Synopsys offers a comprehensive suite of products and services perfectly tailored to this effort. To learn more about how to strengthen your security efforts in your SDLC, visit https://www.synopsys.com/software-integrity.html.

[i] https://www.guru99.com/software-development-life-cycle-tutorial.html

[ii] https://www.techopedia.com/definition/22193/software-development-life-cycle-sdlc

[iii] https://www.veracode.com/blog/2015/09/sdlc-best-practices-5-ways-bridge-application-security-gap-sw

[iv] https://www.synopsys.com/blogs/software-security/devsecops-life-cycle/