Instead of figuring things out as you go along, the software development lifecycle (SDLC) is a formalized process that guides software development from start to finish. Designed to help create consistent and repeatable processes for developing higher-quality software, a formal SDLC is used by most software organizations. While different teams and organizations may have slightly different approaches, most SDLCs follow the same general phases: planning, analysis, design, development, testing, implementation, and maintenance.
Planning is the first stage in the SDLC and is critical to the success of any software application. During this phase, it’s vital to determine a project plan; identify any requirements, dependencies, and risks; and create an achievable objective.
Assessing and defining requirements is also critical to the SDLC. This involves gathering relevant information from customers and cross-functional teams, identifying specific customer-driven functional requirements for the features and functionalities being planned, and aligning them with technical product requirements. An analysis should then be conducted to determine which requirements can be met, and how they should be prioritized.
After the requirements have been identified and vetted, product management and engineering must develop the product architecture. Often, multiple approaches are created and reviewed through several lenses, including risk, cost, and time. Once product and engineering leadership has weighed in, they align on the best course of action for the product.
The development phase is when the code is written. Engineers work to create new source code and/or leverage open source code based on the chosen design and the most effective path forward to build a working version of the software.
Thorough testing is a must, especially for organizations with a security-first mindset. This phase allows you to identify any vulnerabilities, misconfigurations, or bugs within your software, and mitigate them before release. Doing so helps protect your application from cyber-attacks, helping to keep sensitive data safe.
Once all bugs have been addressed, the product is deployed. The outcome is a fully released application that has been thoroughly tested and vetted by your team of engineers in collaboration with security teams.
The SDLC doesn’t stop once a product is live. Ongoing maintenance is required to ensure that the product is functioning correctly and to provide ongoing safety and performance. Iterative changes can also be made to improve existing or add new features, address issues with functionality or usability, and resolve any bugs and/or vulnerabilities as they are identified.
After following all of these steps, organizations will be left with high-quality products that have fewer vulnerabilities, meet predefined business objectives, and address customer demands.
Key terms to know:
- Stakeholders. Stakeholders are all of the individuals, groups, or teams involved in or affected by a particular project.
- SDLC systems. These are all of the systems used during the SDLC, including code repositories, CI/build servers, and artifact registries.
- Risk and opportunity analysis. As part of the SDLC, a risk and opportunity analysis is conducted to determine both the pros and cons of developing a particular feature or product.
- Testing environment. These environments allow development teams to test their applications and address any bugs or misconfigurations before they are deployed in production.
- SDLC models. There are several different SDLC models and methodologies that serve as frameworks for how development teams work. A few examples include Waterfall, Spiral, Lean and Agile.
- Coding guidelines. Coding guidelines are standardized rules that outline how to correctly use different programming languages.
- Software deployment strategy. Software deployment strategies determine how development and operations teams deploy new versions of application code.
- Incident resolution. This is the process of addressing and resolving incidents as they arise to minimize service disruptions while addressing potential risks as quickly as possible.
Today’s seven-phase SDLC is widely accepted by organizations and software development teams around the world—but it hasn’t always been the global standard. As computers became smarter and more widely used, the approach to software development also evolved. What we think of as today’s SDLC was first introduced in the 1960s.
Inspired by other engineering practices, the Waterfall methodology first debuted in the 1970s. This introduced a methodology with a fixed, linear structure that requires finishing one phase before moving on to the next. While the Waterfall method provides precise structure and clearly defines the objective, it also makes it very difficult to implement changes quickly. It also leaves testing until the product is complete, creating numerous inefficiencies that lead to a lot of wasted time and money.
As developers became frustrated with the inherent flaws of Waterfall development over time, other methodologies began to emerge. The Spiral model appeared in 1986 and had four phases: identification of objectives and requirements, design, development, and risk analysis. The process then repeats, creating a spiral-shaped diagram that gives the methodology its name.
In the late 1990s, software development evolved yet again, and the Unified Process model was introduced. Like the Spiral model, the Unified Process has four phases: inception, elaboration, construction, and transition. Developed by a division of IBM, this approach was designed to help minimize risk and create more efficiency throughout development.
Then, in 2001 the Agile methodology came along. This iterative product management process allows teams to move faster by breaking things down into smaller tasks. This allows teams to pivot more easily and increases cross-functional alignment. Scrum, an agile development methodology, still remains a popular approach for teams because of its flexibility, speed, and transparent approach—especially when compared with older methods.
As development methodologies changed, the approach to product development has as well. While operations teams were historically siloed from development teams, that has been slowly changing since the introduction of DevOps in 2007. By breaking down the walls between development and operations teams, DevOps spans the entire SDLC to add efficiency and alignment across organizations, allowing for faster software development and deployment.
As time goes on, it’s only natural that methodologies and philosophies will continue to evolve and change. But there’s one thing that always remains consistent: the software development lifecycle.
Key terms to know:
- DevOps. This is a operating methodology first introduced in 2007 that combines software development and IT operations to create more collaboration, operating efficiency and transparency.
- Application delivery lag. This is the time delay caused by earlier development methods when developers couldn’t keep up with customer demand.
- Working model. A working model is a prototype that allows you to test the functionality of a product.
- Prototype software development. This type of software allows you to create designed prototypes of a product to conduct user testing.
- Sprints. In Agile methodologies, a sprint is a short burst of time, typically two weeks in length, where development teams complete specific tasks.
- Scrum master. In Scrum methodology, a Scrum Master is the team leader who manages the product development process.
As the SDLC has evolved, many methodologies have emerged. These different approaches offer development teams many ways to tackle a project, allowing them to choose the best fit based on several factors. While there is no right or wrong way for teams to approach development, it’s important to understand the basics of each method, along with the pros and cons, to make an informed decision about which is best for your organization.
Waterfall was one of the first SDLC methodologies to emerge. It is a linear approach that requires teams to fully complete each development phase before moving on to the next. While it offers a lot of structure, it can sometimes be too rigid—once a phase is complete, you cannot backtrack. This can sometimes lead to extended development cycles and inefficiency.
An Iterative approach is a philosophy that describes how to approach development by breaking it down into smaller chunks rather than limiting development to only addressing it as a whole. Unlike Waterfall, Iterative development focuses on small, incremental changes and improvements to an application. This allows teams to build products faster and to identify vulnerabilities much earlier in the process. While Waterfall requires detailed upfront planning, the Iterative model does not, which can accelerate the process but also lead to confusion or changes part-way through a project.
Like an Iterative approach, Agile is all about making small, fast changes to your applications. It relies heavily on collaboration and teamwork. Using an Agile methodology, teams work in “sprints” or short periods with a tightly defined set of tasks. These sprints are designed to help teams achieve goals quickly while more easily adapting the application to user feedback.
Lean methodology is all about prioritizing a low-waste and efficient approach. According to this method, there are eight types of waste: motion, over-processing, overproduction, defects, transport, unused talent, waiting, and inventory. By creating a continuous feedback loop, the Lean methodology helps to minimize wasted time and resources, ultimately leading to a more efficient and less costly process.
First introduced in 2007, DevOps is a software development methodology that prioritizes cross-functional collaboration between software engineering and IT operations. By integrating development and operations teams, DevOps helps break down traditional barriers and siloes, leading to more efficient work and streamlining the SDLC.
This method was introduced in 1986, not long after the introduction of the Waterfall model. The Spiral employs modified aspects of some of the practices of the Waterfall methodology, striving for increased efficiency and flexibility. Although it has the same linear structure as Waterfall, the Spiral model is more iterative. The model has four phases— identification of objectives and requirements, design, development, and risk analysis—that then repeats, allowing for adjustments and changes throughout the development process. The model creates a spiral-shaped diagram as the cycle repeats, giving the methodology its name.
The V-model method, sometimes called the Validation or Verification method, pairs every phase of development with a phase of testing. Like the Waterfall method, the V-model is a sequential approach in which each phase must be completed before moving on to the next.
Understanding each of these different methodologies is integral to choosing the right approach for the SDLC at your organization.
Key terms to know:
- Waterfall development methodology. This sequential methodology requires that a phase be completed before moving on to the next step.
- Iterative development methodology. This approach prioritizes fast, incremental changes to an application.
- Agile development methodology. Like the Iterative method, Agile development focuses on incremental product updates with a focus on short sprints dedicated to completing a small number of specific tasks.
- Lean development methodology. Lean development prioritizes profitability by minimizing waste and operating overhead in the SDLC.
- DevOps development methodology. DevOps is a philosophy that breaks down traditional barriers between development and operations teams for a more collaborative approach.
- Spiral development methodology. The Spiral method is a sequential approach like Waterfall that requires completing a phase before moving on. Unlike Waterfall, however, Spiral’s phases are repeated to make incremental changes throughout the SDLC.
- V-model development methodology. The V-model method pairs every phase of the SDLC with a testing period before moving on to the next phase.
- Verification. Verification is the process of determining if a product meets the initial product requirements.
- Validation. Validation is the process of determining if a product meets business or client requirements.
- Waste reduction. Waste reduction is the process of removing inefficiencies from your SDLC.
Since the SDLC was first introduced, the world has changed drastically. Now, computers are commonplace, smartphones are everywhere, and technology innovation is progressing at an impressive rate. This new world has resulted in a new business environment with constantly evolving priorities and expectations for software development, which calls for periodic reevaluation of our approaches to the SDLC.
In today’s landscape, business leaders value business agility and the rapid delivery of new application features to meet customer requests and requirements. Instead of a slow, methodical approach, they prefer to move faster to gain a competitive advantage. At the same time, software development leaders are striving to create environments that improve developer productivity and attract and retain top talent. These top performers, unsurprisingly, are often attracted to more modern companies that prioritize newer development approaches, like Agile.
Traditionally, security assessments and remediation have been left until the final stages of the software development framework, especially in older approaches like Waterfall. But as the technology landscape changes, this approach to security testing is changing, too. With today’s increasingly common cyber attacks targeting the software supply chain—specifically, those attacking the pre-product development environment—security must be addressed much earlier in the SDLC to prevent potentially devastating results–particularly once that code makes it into production.
GitHub, for example, is a popular source code management (SCM) system used by many organizations. Although convenient and useful, it has a few inherent security risks. Because it is so flexible, it opens the door for misconfigurations and human error that can open organizations up to attacks. It also doesn’t offer default configurations, leading to increased security exposure—especially for more inexperienced users. As it has gained popularity, GitHub has become a relatively easy target for cybercriminals looking to take advantage.
In 2020, SolarWinds—a system management software provider—was the victim of a devastating cyber attack. Hackers breached their software supply chain and gained access to the networks and systems of thousands of SolarWinds’ customers. Over 30,000 organizations were compromised in this attack.
These examples demonstrate the need for strict and thorough security measures within an organization’s own SDLC to secure their software supply chain. Without prioritizing these types of security protocols, it’s all too easy for businesses to fall victim to these types of attacks. But implementing security throughout SDLC can help organizations identify vulnerabilities earlier and keep their software supply chain better protected.
Key terms to know:
- Business agility. Business agility describes an organization’s ability to adapt to emerging and evolving market demands.
- Feature backlog. In Agile, a feature backlog is a prioritized list of tasks for the development team to work through.
- Software quality standards. These standards help ensure that new products meet or exceed a specific list of requirements and specifications.
- Stakeholder requirements. These requirements detail the features and functionality that a product must have to meet customer or business demand.
- Deep collaboration. This type of cross-functional partnership is designed to help teams increase productivity by working together more collaboratively.
- Software-as-a-Service (SaaS). SaaS products are cloud-based software solutions that are accessed over the internet, typically through a subscription service. Common examples include Slack, Salesforce, and Google Suite.
Prioritizing SDLC security is vital to protecting your software supply chain and limiting the likelihood of successful cyber attacks. Software supply chain attacks have been on the rise, with some estimating these attacks occuring three to six times more frequently than in the past.
Mitigating these risks is critical to the success of any organization. Software supply chain attacks disrupt business operations, enable lateral attacks on other critical internal systems, and can embed vulnerabilities in your software that open up customers and clients to added risk.
To prevent attacks, earlier identification of critical security vulnerabilities in the pre-production SDLC environment is vital. It not only reduces the cost of having to address vulnerabilities by resolving them before they’re released into production, but also reduces the time it takes to implement a resolution.
Prioritizing your software supply chain security can also help improve organization-wide security—particularly throughout the software development process. But to do so, you must first implement a security-first approach across your SDLC. Instead of leaving security to the end of the process, shifting left and implementing continuous security at multiple touchpoints adds efficiency. Using this preventative approach helps reduce intrinsic business risks and prevent widespread negative impacts including:
- Damaged reputation. If your company is the victim of a highly public cyber attack, it can irreparably damage your reputation. You’ll no longer be viewed as a trustworthy industry leader, and customers will be less likely to leverage your services if they feel that you can’t protect their data.
- Stock value. Cyber attacks can be devastating for publicly traded companies. When an attack happens, it understandably spooks investors, which can lead to plummeting stock prices. This not only devalues the company overall but also can further damage your company’s reputation in the eyes of your customers. If a breach is the result of failure to meet specific compliance requirements, costly fines and required disclosures can further reduce the value of a company’s stock.
- Customer relationships. Customer trust should always be a top priority for companies across industries—and a cyber attack that leads to compromised or leaked data can wipe away that trust in an instant.
- Customer retention. Once customer trust is lost, it’s unlikely that those same customers will renew their services. Even if your offering and pricing lead the industry, it’s challenging for organizations to retain customers that have had their data compromised. It is typically much more expensive to recover a lost customer than it is to retain them.
- Sales. A damaged reputation, low stock value, and tenuous customer relationships often lead to a drop in sales. Cyber attacks not only have consequences for your business’s reputation, but also for your ability to generate new revenue. As current customers jump ship and new customers are hesitant to buy, a lack of sales—and dwindling revenue—can be one of the biggest challenges to overcome.
Instead, maintaining strict security measures and continually operating with a security-first mindset can help prevent these devastating incidents and keep your organization protected.
Key terms to know:
- Vulnerabilities. Vulnerabilities are weaknesses in your product or application that leave you open to cyber attacks.
- Patching software. This type of software is designed to implement patches that update code and fix security vulnerabilities within existing software.
- Malicious code injection. This is a type of cyber attack that involves inserting malicious code into an existing product or application through an input field like a website form.
- Denial of service (DoS) attacks. In this type of cyber attack, hackers overwhelm an application with a flood of requests and prevent legitimate users from gaining access or using the application.
- Automated security tools. These tools are designed to automatically help identify any existing security vulnerabilities within a product or application.
- Secure coding practices. These are practices, principles, and protocols designed to help keep code secure and prevent vulnerabilities from being introduced during the SDLC.
- Security issues. Security issues are vulnerabilities, secrets or misconfigurations that can be exploited within your code or application.
- Application security. Application security includes all of the security measures within your SDLC that are designed to mitigate risk and protect against vulnerabilities.
- Source code. Source code is the core programming that is the foundation of any application.
Implementing security measures throughout your SDLC can be a daunting task. But there are certain best practices that organizations can follow to heighten security and keep their applications and organization protected.
Improve Data Security
Having a clearly defined data security strategy is a critical aspect of protecting your software supply chain. Your strategy should include guidelines for everything from implementing security best practices throughout the SDLC with clearly defined risk management strategies to enforcing strong access control and other regulatory compliance requirements.
Implement Strict Access Control
Evaluating your access permissions regularly is a must to keep your software supply chain secure. Use the principle of least privilege when possible, and only grant access to the resources required for team members to complete their tasks. Reexamine your access permissions regularly to ensure you’re revoking access from those who no longer need it.
Track All Data
Knowing where your data is stored and having an up-to-date inventory of all entry and exit points allow you to closely monitor everything. Tracking access to data and the cloning and forking of code that may contain access to data can help you to stay ahead of possible security risks and ensure you always know who or what is accessing your data. It’s also helpful to keep track of when data is outdated or no longer needed, so that you can remove it from your repositories to keep everything current.
Regularly Evaluate Risk
Don’t wait for attacks to happen before evaluating your security posture—instead, stay on top of your risk at all times. Proactively identifying vulnerabilities is a best practice that helps you stay ahead of potential exploits and threats. Automated vulnerability scans help reduce the workload on your team and will identify vulnerabilities that might be overlooked during software development. Leverage these tools to scan code, SDLC pipelines, systems, and infrastructure for comprehensive coverage.
Leverage Discovery Tools
It’s not always easy to keep track of where your data is stored. Discovery tools can help you quickly find it, including data that might be stored in a forgotten, vulnerable location. Discover tools can search through your entire software supply chain, including repositories, servers, and artifact repositories, to find unused data that have been otherwise overlooked or would require extensive manual effort to locate and document.
Monitor Access Activity
Keeping track of who accesses your data and files, and when, can help you spot suspicious activity before it becomes a potentially catastrophic breach. Use automated security tools to detect and notify you when suspicious or unusual access happens so you can stay ahead of the game.
Following these best practices can help you keep your SDLC protected and prevent cyber attacks before they happen.
Key terms to know:
- Threat modeling. Threat modeling helps you identify weaknesses and vulnerabilities in your application.
- Security test cases. A security test case allows you to evaluate whether or not an application is functioning properly.
- Shift-left. Shift-left is a testing method that involves incorporating security testing early on in the SDLC.
- Stakeholder awareness. Stakeholders are all those involved in a project, from software development and IT operations teams to customers and business leaders. Stakeholder awareness requires communicating clearly with all involved about changes and updates.
- Cryptography. Cryptography is used to protect data and facilitate secure communication through the use of codes, so that only those for whom the information is intended can read and process it.
- Exploits. An exploit is a type of attack, often used by hackers, that uses a security vulnerability in existing software to its advantage. It can allow hackers to perform a wide range of malicious actions like accessing data or completely taking over a system.
- Third-party code. This is code that is open source or comes from an external vendor or is available via licensing that isn’t written by first-party, internal teams.
- SAST. Static application security testing allows you to evaluate source code and scan for security vulnerabilities.
- SCA. A software composition analysis (SCA) solution evaluates your code and identifies any open source code used in your code repository for additional risk analysis and added security.
Since its inception, the SDLC has been continuously evolving. While we’ve come a long way, the next iteration of the SDLC will have some important differences from where we stand today.
Increased Automation & Machine Learning
The introduction of DevOps and automation tools have moved the SDLC for many orgs leaps and bounds ahead of where it used to be. But efficiency can only bring you so far. To take the SDLC to the next level, we expect that machine learning will be increasingly employed by a growing number of organizations. Instead of bringing on countless team members, these automated tools will be able to write code and run tests with unbeatable efficiency, allowing organizations to not only innovate faster but also to develop new code and applications more securely.
Enhanced Security Across the Software Supply Chain
Security has grown significantly more important as cyber attacks have become increasingly common and attackers have become more and more sophisticated. To keep up, organizations must continue to evolve their security measures to better protect themselves across their entire SDLC. New SCA and SAST tools are emerging to continuously scan code for vulnerabilities, and new DAST tools are being created to work directly within runtime code to better assess risk and remediate vulnerabilities.
As DevSecOps and the SSDLC have become a priority, shift-left testing has been the focus as of late. And while ongoing testing throughout the SDLC is imperative, it’s also vital to evaluate products in a production environment—not just a staging environment. Doing so allows teams to validate and verify software in the real world and ensure a higher-quality final product.
Increased Attention on Reliability & Supportability
While the main phases of the SDLC are effective, they leave out important elements like reliability and supportability. Prioritizing reliability, resilience, and supportability, incorporating them into the SDLC, and integrating site reliability engineering teams into the process from the beginning helps to future-proof your applications.
Key terms to know:
- SSDLC. The secure software development lifecycle, or SSDLC, is the end-to-end process of developing software with a security-first mindset integrated into the entire process.
- Cybercriminals. These are malicious actors, like hackers, who commit cyber crimes for financial gain or to create chaos and cause damage.
- State-sponsored attacks. These types of cyber attacks are committed by cyber criminals who are funded by or affiliated with a nation or nation-state.
- Integrated security. This approach integrates security throughout the development process instead of leaving it to the end phase.
- CI/CD security. Continuous improvement/continuous development, or CI/CD, security is the process of identifying and resolving risks early in the SDLC to allow for faster innovation without compromising application security.
- Continuous security strategy. A continuous security strategy requires continuous security monitoring and risk remediation to identify threats and vulnerabilities.
- Secure coding training. This type of training empowers engineers to develop more secure code by educating them about security best practices.
- Ethical hackers. Ethical hackers are those who help organizations improve their security posture by using various tactics and techniques to try and gain unauthorized access to computer systems. This allows organizations to identify vulnerabilities and proactively prevent malicious attacks.