Secure Software Development 101+ Best Practices


Software systems are becoming more sophisticated as we continue to march deeper into the digital age. Unfortunately, hackers are becoming more sophisticated, too, adopting new and novel ways to target and expose sensitive information. 

That’s why it’s more important than ever that organizations take preventative measures to minimize security vulnerabilities across the entire software development life cycle. Read on as we take a closer look at secure software development, what it entails, and how to apply it to your business’s best practices.

What Is Secure Software Development?

Secure software development makes the security of your applications a core component of your SDLC. This methodology integrates security testing and other activities into all phases and facets of the development process, from planning to release, for an approach that’s proactive as opposed to reactive. 

Identifying and mitigating vulnerabilities from the start is vital to secure software—and following certain best practices and frameworks, like NIST, can help set your SDLC up for success. 

These are some of the most common SDLC methodologies. These methodologies are often used in tandem with one another, and each has its own influence on your ability to perform secure application development:

Waterfall. Waterfall software development is one of the first structured SDLC methods. This linear process involves finishing one phase before moving on to the next. Because you can’t go back or make revisions throughout the process, it’s not typically used for long-term or undefined projects. Waterfall development does introduce certain security risks. Unlike the Agile methodology where you are continuously iterating, Waterfall is a strictly linear process that doesn’t allow for backtracking. If a security risk or vulnerability is missed, it remains in the product until delivery. 

Agile. Agile software development is often considered the industry standard. Agile development involves ongoing product release cycles that have small changes. This allows teams to “fail fast” while also addressing small issues, incorporating feedback, and iterating. The Agile methodology—and other similar approaches addresses later like Iterative and Scrum—prioritize developing the product quickly over keeping product documentation up-to-date. As a result, this can increase your risk throughout the development process. Because changes are made so quickly, it’s easy to lose track of documentation, and because teams are moving so fast, security protocols are often broken or forgotten.

Iterative. The Iterative development model involves extensive repetition. Instead of defining requirements at the beginning, Iterative development involves testing and evaluating the application as you go along. This makes it easier to implement changes—but can also be time-consuming and expensive. As with Agile development, the main priority with an Iterative approach is advancing the product, and documentation needed to maintain security best practices can be neglected.

DevOps. DevOps involves developers and operations teams working together, creating a more collaborative approach to the SDLC. By pairing these two teams from the beginning, DevOps helps accelerate the evolution of the software product. The speed of DevOps can make it hard for security teams to stay on top of application security. Establishing a DevSecOps program can help you keep up with the rapid pace of change.

Lean. Lean development has seven principles: eliminate waste, create knowledge, build in quality, deliver fast, empower the team, delay decision-making, and optimize the whole. In Lean development, there is no multitasking; instead, teams focus on one product at a time to streamline development.

RAD. The RAD, or Rapid Application Development, methodology is a form of Agile methodology. It has four stages: Business modeling, data modeling, process modeling, and application generation. Like Agile development, it involves frequent iterations. And like with Agile, the emphasis on fast product development can introduce a lot of risk into the SDLC.

Big Bang. Big Bang methodology is best for small teams and small projects. This simple approach requires little to no planning, quick growth, and fast product completion. Application security sometimes becomes an afterthought in this approach.

Scrum. Scrum is an Agile methodology that is designed to be fast and flexible. Like Agile, Scrum involves an interactive process that is made up of sprints, planning, and review. And like Agile, the speed of Scrum development can create problems for application security teams.

Key terms to know:

  • SDLC. SDLC, or the Software Development Lifecycle, is the process of planning, developing, and deploying new software.

  • SDLC phases. The main phases of the SDLC are planning, analysis, design, implementation, and maintenance.

  • SSDLC. SSDLC, or Secure Software Development Lifecycle, is the process of integrating security throughout every stage of the software development cycle.

  • Waterfall development. The Waterfall development SDLC methodology refers to a linear process that is broken down into sequential phases, where every phase depends on those previous to it.

  • Agile development. The Agile methodology involves continuous improvement throughout the development process. This is done through frequent iteration and releases.

  • Iterative development. Iterative development is similar to agile development. It is broken down into four main stages: planning, analysis, implementation, and evaluation.

  • DevOps. DevOps is an SDLC methodology that involves pairing development and operations teams to encourage collaboration for faster and more efficient innovation.

  • NIST. The National Institute of Standards and Technology is an agency within the United States Department of Commerce. Their mission is to promote innovation and help organizations better understand and manage cybersecurity risk.

SSDLC History

Keeping the software development lifecycle secure isn’t a new concept. But as the software development lifecycle has evolved, it has become clearer that security isn’t just a phase that can be built into the end of the process. 

Traditionally, the SDLC has seven stages: planning, analysis, design, development, testing, implementation, and maintenance. Security testing is commonly done in the development stage when you would perform a static analysis to identify risks or flaws in the code. This approach, however, doesn’t allow developers to continuously adjust and improve the product over time or identify vulnerabilities as they go. As a result, this can lead to increased risk and a greater probability of a breach or malicious attack.

Instead, security testing needs to be integrated throughout. This need is how the SSDLC and DevSecOps were born. Embedding security directly into the DevOps process helps businesses of all types prevent unwanted data breaches. While some may think that DevSecOps is too time-consuming for small teams, it can free up time in the long run by streamlining the security process. It also helps teams stay ahead of malicious actors and go above and beyond regulatory compliance to continuously improve.

Whether companies use self-built or third-party security tools, implementing security solutions is vital in helping to prevent breaches like SolarWind that can compromise not only your software supply chain, but that of your customers or clients.

Key terms to know:

  • CI/CD. CI/CD is the practice of continuous integration and continuous deployment. This results in frequent software changes and increased reliability.

  • DevSecOps. Similar to DevOps, DevSecOps — or development, security, and operations — is a collaborative approach to software development that includes security and operations throughout the entire process.

  • Static analysis. Static analysis is an assessment of the program code — without executing the program. It is also sometimes referred to as code analysis. 

  • Software Composition Analysis (SCA). SCA is an automated process that identifies the open source software in a codebase. It is performed to evaluate security, license compliance, and code quality. It can help development teams track and analyze any open source component brought into a project by scanning dependencies for security vulnerabilities.

  • Attack surface analysis. An attack surface analysis is a process of assessing all of the vulnerabilities within your systems. This allows you to better minimize and mitigate risk factors and keep your SDLC secure.

  • Source code. Source code is the fundamental code developed to create an application. It is created by a programmer and written in one of several programming languages. 

  • Infrastructure-as-Code (IaC). IaC is the managing and provisioning of infrastructure through code instead of through manual processes. It uses DevOps methodology and versioning with a descriptive model to define and deploy infrastructure and requires three elements to function: resource pooling, software defined intelligence, and a unified API.

  • Third-party code. Third-party code is code that is not created by your in-house development team. This code is often developed and sold by vendors, or available via open-source licensing. 

  • Open source code. Open source code is code that is written and made available to the public, usually for free, by the copyright holder. Open source code can then be changed or updated to use in the development of any application.

Why Secure Software Development Matters

There’s never been a better time to shift left and take a security-first approach to managing the SDLC. As breaches become more common and attackers become smarter, more and more companies are falling prey to their malicious attacks. 

The SolarWinds attack is a prime example. SolarWinds, which offers system management tools for network and infrastructure monitoring for organizations around the globe, was the victim of a widespread supply chain breach in 2019 of the Solarwinds Orion system. Hackers inserted malicious code into the Orion system and used it to infiltrate the networks, systems and data of thousands of SolarWinds’ customers. It also allowed the hackers to get additional info from SolarWinds customers and partners, creating a domino effect of compromised companies. 

Prioritizing security within the development process can help prevent these targeted attacks. An SSDLC approach is vital to keeping your applications and your business protected in a few key ways: 

  • Protect your brand and reputation. Not all press is good press. If you’re the target of a successful cyber attack, your company’s name will likely spend some time in the spotlight—but not in a good way. An SSDLC, on the other hand, can help you control the narrative and avoid any negative press coverage related to a damaging cyber attack or a data breach.

  • Protect from financial risk. Breaches and leaks can not only damage your reputation but also cost your company money. If your network is breached and sensitive or protected data is stolen, it can lead to expensive lawsuits or loss of customers, in turn resulting in high fees and loss of revenue. Creating secure applications from the start can help you avoid these repercussions. 

  • Protect from regulatory fines. By keeping cyber security at the core of everything you do, you’ll likely exceed most regulations, helping you avoid unwanted fees and fines. 
  • Avoid customer dissatisfaction and abandonment. When customer data is leaked due to a vulnerable software supply chain or insecure application, it’s understandable that customers will be angry. This can lead to a mass exodus of your customers and negative brand awareness that impacts your business.

  • Save time and money by catching and fixing vulnerabilities in pre-production. Instead of spinning your wheels or spending time and money to fix mistakes after the fact, an SSDLC helps you catch vulnerabilities before they’ve made it into production. This not only helps you simplify your SDLC processes but also keeps security costs down.

  • Automate security practices for improved productivity. Security automation can help you simplify your SSDLC and prioritize security—without diminishing your team’s resources—by automating slow, manual processes.

  • Avoid business disruptions due to security breaches and keep your SDLC on track. With proper security processes in place, your application development teams can keep their focus on what matters—building the best possible applications.

  • Improve cross-functional collaboration between application development and security teams. Integrating security into your DevOps through better communication and collaboration between different teams allows you to adopt a DevSecOps approach. When done right, this security-oriented process saves time, money, and resources.

By prioritizing an SSDLC, you can not only streamline the development lifecycle, but enforce secure protocols, rapidly release secure software, and create a culture with security at the center.

Key terms to know:
  • Application security. Application security is the process of identifying, testing, and fixing any security vulnerabilities in your applications.

  • Cybercrime. Cybercrime is an umbrella term that includes any crime or malicious attack committed by using a computer or computer network. 

  • Cybersecurity. Cybersecurity is the practice of protecting your computer systems from being breached or damaged by malicious actors, like hackers. 

  • Security-minded culture. A security-minded company culture is one in which security is at the core of your SDLC. 

  • Security Champion. A security champion is a member of the software development team who acts as an extension of the security team, actively looking for potential vulnerabilities and other risks being introduced into the SDLC that require expertise and/or intervention by a security professional.

  • Risk analysis. Risk analysis involves identifying any vulnerabilities or weaknesses within your SSDLC or application itself. 

  • Gap analysis. A gap analysis allows you to compare actual performance with desired performance. If actual and desired performance is misaligned, a gap analysis also helps identify what steps need to be taken to reach alignment.

  • Third-party software. Third-party software is software that is not developed by your in-house team but rather created by another company or vendor. It can be commercial or open source.

  • Access management. Access management requires monitoring and managing  who has permissions to access each component of your software supply chain.

Secure Software Development Best Practices

Creating a secure software development lifecycle takes time. Adhering to a few tried-and-true methods can help you quickly transform your SDLC and reinforce it with the level of security that you’re looking for.

Use these best practices to help improve your SSDLC:

1. Establish specific security guidelines and recommendations from the beginning.

Start strong. Develop your internal security guidelines from the start and implement them throughout the SSDLC to ensure that every phase of development is as secure as the others.

2. Establish hierarchical security practices across coding, SDLC tools, and development frameworks for the entire DevOps team.

Creating hierarchical security practices helps you create an even more secure software supply chain. Implement different processes and protocols across components, and propagate them across teams to keep your entire org on the same page.

3. Develop a vulnerability risk rating mapped to your business to help focus on high-priority vulnerabilities first.

Not all threats are created equal. Develop an internal risk-based vulnerability scoring system to determine the actual level of risk to your environment associated with various vulnerabilities. That way, as they’re uncovered, your team is already equipped with how to prioritize and mitigate.

4. Don’t wait until deployment to perform a risk analysis.

An SSDLC involves integrating security throughout the entire process—not just at the end. For the most secure outcome, it’s vital to perform a risk analysis and make the necessary adjustments based on the outcome, throughout your entire development lifecycle.

5. Establish frequency for security audits from day one, then perform at the required frequency.

Application security isn’t a one-and-done process that you can check off your to-do list. Instead, you should approach it with a continuous improvement mindset. Continually auditing your processes, assessing their effectiveness, and improving your protocols are vital to preventing future vulnerabilities.

6. Use automated tools wherever possible for completing simple, repetitive tasks involved with security audits, code reviews, open-source vulnerability scans, and penetration tests.

Security automation helps keep your team focused on higher skill activities while also addressing vulnerabilities as they arise. It helps eliminate human error and functions as an extension of your team. Automated software tools  can also make changes quickly and scan for vulnerabilities and risk  across different phases of the application development process including coding, reviewing, testing, and deployment. 

7. Foster a security-first mindset in all team members, starting from the leadership level on down.

A top-down approach to security is vital to creating a culture change. As the importance of developing secure software to support CI/CD initiatives grows, organizational leaders need to champion the new approach to help chain the mentality among their teams. Dedicating time and resources to DevSecOps initiatives and allowing teams extra time to address security issues, while providing the tools they need to do so, can help showcase their commitment to security. 


Key terms to know:
  • Software releases. A software release is the distribution of your final software application. 

  • Threat modeling. Threat modeling is a process that allows you to identify and mitigate vulnerabilities and weaknesses within your application.

  • Risk analysis. Risk analysis allows you to identify, analyze and prioritize the possible risks associated with code in any given application, allowing you to better manage and secure your software supply chain.

  • Shift left security. Shift-left security describes the process of testing and evaluating code at the beginning of the SDLC. This allows your development teams to improve the overall quality and identify any risks much earlier in the development process, ultimately saving time and reducing the amount of risk that makes it into production code.

  • Code scanning tools (SAST and SCA). Static application security testing (SAST) and software composition analysis (SCA) are automated tools that evaluate your pre-production code and identify any possible vulnerabilities and risk.
  • DAST. Dynamic application security testing (DAST), describes tools that identify common security weaknesses, vulnerabilities and risk within your production software.
  • Software security initiative (SSI). A software security initiative, or SSI, describes the policies and protocols of your organization’s security program.

How to Implement Secure Software Development in Your SDLC Processes

Adding security measures to your software development lifecycle may seem daunting, but it doesn’t have to be. Use these six basic steps to help guide you as you implement a “security in every phase” mentality.

  1. Planning
    When initially planning your SSDLC, involve developers and security experts from the get-go. This will allow them to collaborate on developing the  initial risk assessment and will help prepare an integrated strategy for efficiently addressing the most common risks at the beginning of the SDLC to set you up for future success.

  2. Analysis
    You should analyze how your application security is being performed and whether or not you have gaps or redundancies at each stage of the SDLC to identify any areas for improvement. Involving security experts ensures you have the help you need to decide which technology, frameworks, and languages should be used in your SSDLC—and will also help you accurately consider associated vulnerabilities from every angle.

  3. System design
    Perform security testing and address vulnerabilities early on in the design phase to minimize issues down the line.

  4. Development
    Implement secure developer practices and secure coding standards to improve application security. These practices can help reduce the number of vulnerabilities introduced during the deployment phase, saving time and resources later in the SDLC. It also helps developers reduce the risk of IP theft, unauthorized access, and insecure configuration of SDLC systems and tools.

  5. Testing
    Establish concrete policies for security review and testing frequency, and use automated security testing tools whenever possible to save your team time and eliminate human error.

  6. Maintenance
    Any new releases or updates should be put through the same level of security scrutiny as the initial deployment to maintain a continuously high level of security. Don’t wait until you’re too far along in your production to initiate security reviews. Instead, address risks as they are identified throughout the SDLC to maintain your commitment to rigorous security standards. 

Taking these steps not only creates more secure and resilient applications, but also helps you reduce cost, minimize risk, and go-to-market faster.

Key terms to know:

  • Secure software development standards. These standards define how to incorporate security at every phase of your software development lifecycle (SDLC).

  • Secure software development process. Developing secure software requires close collaboration between development, operations, and security teams. This leads to a collaborative approach to building a SSDLC, or secure software development lifecycle.

  • Secure software development best practices. Outlining and distributing a set of secure software development best practices can ensure your entire organization is on the same page and remains committed to implementing necessary security measures.

  • Security baselines. A security baseline identifies and defines the minimum level of security controls you need to put in place to protect your systems and/or applications.

  • Integrated development environment (IDE). An integrated development environment, or IDE, is an application that allows developers to code more efficiently. They typically include a code editor and other tools for building, testing and packing to streamline application development.

  • Cloud security. Cloud security is an umbrella term that describes various technologies and applications that work to protect data, applications and infrastructure involved in cloud computing.

  • Software-defined perimeter. This type of virtual boundary is a security measure that separates  company assets at the network layer. This prevents hackers or cyber attackers from accessing any unauthorized information by restricting user privileges.

  • Secure coding. Secure coding is a development process that helps to protect against vulnerabilities and weaknesses being developed within the application, reducing the number of security issues that make it into production.

  • Third-party libraries. Third-party libraries are repositories of existing code from outside the organizations that developers can leverage when building an application. These can be either commercial or open source libraries

Future Predictions for the SSDLC

By implementing security best practices throughout the SDLC, organizations and teams can help increase the security of their applications and mitigate risk more effectively. But as technology continues to evolve, the best practices around creating an SSDLC will likely continue to morph and change.

Software Supply Chain Security
Focusing on security throughout the entire development process empowers you to protect your entire pre-production application development environment before making it into production where attacks are most likely to happen. Incorporating real-time SDLC auto-discovery and analysis and CI/DC pipeline security will help you take your security measures to the next level, allowing your teams to work more efficiently and have added peace of mind. 

Unified Application Security Control Plane
A unified security control plane helps consolidate all of your security measures in one place. This added efficiency to your application security program can help boost productivity and efficiency while delivering continuous visibility and awareness of your application security posture. 

Code-To-Cloud Traceability & Security
Map application pipelines from source code to deployment to contextualize security risks and prioritize remediation. This allows you to prioritize actions based on actual production risk and to trace the source of vulnerabilities to their original developer. Having a secure delivery checkpoint also ensures that you can protect your application from threats.

Compliance and SBOM
Release applications quickly while ensuring software integrity, tamper prevention, and compliance. Creating a comprehensive software bill of materials allows you to inventory your entire software supply chain and remain compliant with any regulations. It also upholds your application release integrity, helping to demonstrate your commitment to security to auditors, customers and partners.

Artificial Intelligence
Automated security applications are the first step in removing human error from the SSDLC—but AI is the future. Leveraging AI throughout the entire lifecycle can help minimize or eliminate vulnerabilities resulting from human error or oversight. AI can quickly identify and resolve issues in the code to enhance security even further. As AI technology evolves, adversarial AI may also be able to predict and defend against AI attacks. 

Building security best practices is the most fool-proof way to create a more software supply chain. Creating applications that inherently adopt best practices—instead of pushing risk ownership onto individual developers or the application development team—reduces operating overhead and results in an SSDLC that is more intelligent and secure from the very beginning.

Key terms to know:

  • App architecture. App architecture is a term that describes the techniques and structure used to build an application.

  • Conditional controls. Conditional controls are actions that are taken only if other circumstances are met.

  • Adversarial AI. Adversarial AI is an AI application that can identify and defend against vulnerabilities and attacks.

  • Legacy application code. A legacy code application is an application that has old code no longer supported.

  • Cryptography. Cryptography is the practice and study of techniques for secure communication. It is used to prevent outside parties from reading communications and messages.
  • Multifactor authentication. Multifactor authentication is an access control method that requires the user to provide two or more verification factors.
  • Data disposal. Data disposal refers to the process of erasing or overwriting software. It is also called data destruction or data erasure.
  • Data retention. Data retention determines how long and where you store data and records.

  • OpenSAMM. This open software assurance maturity model framework is designed to help organizations develop and deploy strategies for software security.

  • BSIMM. BSIMM, or Building Security In Maturity Model, is a study of software security initiatives that allow organizations to compare and improve their security measures.

Adopt the Secure SDLC Approach to Boost Security

As hackers become more sophisticated and threats become larger, a security-first mindset in application development is a must. By developing secure applications, you not only protect your own brand’s reputation and maintain customer satisfaction, but also save time and money. 

Implementing a few best practices will set your team up for success. Software supply chain security applications, like Legit Security, can help to eliminate human error and assess vulnerabilities from every angle throughout the entire SDLC. 


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