A Secure software development lifecycle bakes security into applications from the get-go, driving everything from better quality software to cost savings. Here’s what you need to know.
The Evolution of the SDLC
In the early days of software development, security was often an afterthought. Indeed, until the 1950s and 1960s, software development was largely a trial-and-error process; it was only when more complex, commercial systems emerged that a need for a more structured approach was recognized, and the Software Development Lifecycle (SDLC) was born. Since then, we’ve seen it evolve through Waterfall, structured programming, Rapid Application Development, Agile, Scrum, and into today’s DevOps and CI/CD (Continuous Integration/Continuous Deployment).
Source: OX Security
The early development process was heavily skewed towards functionality, reliability, and efficiency, with little regard to security – and that made sense in a world where systems operated in controlled environments, with little potential for outside attack. Even when Bob Thomas’s “Creeper” virus/worm appeared in the early 1970s, it was described as more like an “allergy test than a common cold” – no more than 28 machines could have been impacted.
Secure Software Development Emerges
All of that changed when the internet and connected systems became the norm in the 1990s and, with them, new security risks emerged. SDLC security gained recognition, and security testing tools like static code analysis and vulnerability scanners began emerging. These were mainly used at the end of the software application development process, with a focus on identifying vulnerabilities before deployment rather than earlier in the design phase.
However, by the early 2000s, security breaches were becoming more widespread and severe. Development teams and security practitioners began collaborating to develop and formalize more secure coding practices, including key milestones:
- The Open Web Application Security Project (OWASP) was established in 2001 and, with it, the beginning of widely accepted guidelines for secure web application development.
- Microsoft introduced its Security Development Lifecycle (SDL) in 2004. This became the bedrock of secure coding practices, emphasizing threat modeling, secure software and coding standards, and regular security testing. The goal was to embed security practices into every phase of development, from design to deployment.
- The rise of DevOps in the 2010s leads to the concept of DevSecOps – the detection and resolution of security issues earlier in the SDLC by embedding security into CI/CD pipelines.
- “Shift Left” started to gain traction in the context of DevSecOps, advocating for the integration of security measures early in the SDLC – further over to the “left” on a traditional SDLC timeline.
- Formal standards and frameworks, such as NIST SP 800-64 and ISO/IEC 27034 arrived in the 2010s, giving a formal foundation for security in SDLC.
Today, the SDLC and security go hand-in-hand. As companies not rooted in software development increasingly build, develop, ship, and integrate software into their network environments, the need for a safe SDLC is critical.
What is a Secure SDLC, and Why is it Important?
A secure software development lifecycle (SSDLC) integrates security measures into every stage of the software development process, from design to implementation and maintenance. Unlike traditional SDLC, where security requirements are often limited to the final stages, once coding is finished, SSDLC is a proactive approach that puts security at the core of development. SSDLC ensures that security is a continuous focus, helping identify and mitigate potential vulnerabilities early in the SDLC and underpinning overall software security.
Why Does a Secure Software Development Lifecycle Matter?
Today’s fast-paced software development relies heavily on the reuse of open-source and third-party code. The benefits of reusing code are well-documented: accelerated software development and deployment, greater time to focus on new features, cost reduction, consistency, and scalability.
Source: OX Security
Unfortunately, that flexibility comes with a high price tag in terms of security risk. The result is often a software supply chain plagued with security vulnerabilities and code that hasn’t been updated or patched. Almost 90% of codebases contain open-source code over four years old, and 91% haven’t had new development in over two years. In a world where as much as 80% of code in modern applications originates with open-source projects, the opportunity to keep reintroducing flaws is high, and it shows:
- Command injection (15.4% of applications)
- Sensitive data in log files (12.4% of applications)
- Cross-site scripting (XSS – 11.4% of applications)
All three of the most common software weaknesses listed above are known vulnerabilities tied to attack vectors that have been known — and exploited — for many years. Secure coding practices and continuous testing help significantly reduce these risks and protect applications from the very start of the software development process.
When developers and AppSec practitioners collaborate to embed security early and consistently throughout the SDLC, organizations can develop applications more resilient to security vulnerabilities and attacks. The result: better quality, more secure software. Here’s how it works.
How Does SSDLC Work?
The secure software development lifecycle follows a structured process, embedding security at every phase of software development. Application security practices including threat modeling, secure coding, and automated testing are introduced early, allowing teams to collaborate and address issues before they escalate into more systemic problems.
This process can be broken into five key steps:
The Five Phases of Secure SDLC
Phase 1: Requirements
Functional and security requirements are gathered and defined. Teams identify potential threats and define the security measures needed to resolve or mitigate them. This typically includes risk assessment, SDLC security requirements documentation, and initial threat modeling.
Phase 2: Design
At this stage, the requirements are developed into a workable, secure solution: architecture, protocols, secure data flows, and access controls. This is where “secure by design” principles come into play, helping ensure that potential vulnerabilities are mitigated early in the process.
Phase 3: Development
At the coding stage, secure practices are applied, preventing the introduction of security vulnerabilities such as cross-site scripting or injection attacks. Security tools such as Static Application Security Testing (SAST) and Software Composition Analysis (SCA) are used to ensure secure code.
Phase 4: Verification
At this stage, testing is crucial; it roots out any lingering security risks. Penetration testing, Dynamic Application Security Testing (DAST), and validation of third-party libraries and components to mitigate software supply chain risk happen during this phase. Many teams automate security testing to minimize manual tasks in their accelerated development environment. Security issues during testing trigger a return to phase two or three for remediation.
Phase 5: Deployment and maintenance
The software is deployed, but security remains a priority: final reviews occur, and regular monitoring, patching, and incident response planning protocols are established. These are all crucial to ensuring SDLC compliance.
Within these phases, key areas of SSDLC exist to ensure each phase is successful.
Secure Your SDLC: Key Components of a Secure Software Development Lifecycle
Several key components ensure that each phase of the SSDLC process results in secure, reliable, and functional software. These best practices include:
Threat modeling:
Helps identify potential threats and vulnerabilities early in the design phase.
Secure coding standards:
Including OWASP Secure Coding Practices, CERT Secure Coding Standard, and NIST Secure Coding Guidelines. Combined with ongoing security training and awareness for developers, implementing secure coding standards helps minimize the introduction or reintroduction of vulnerabilities, such as validating inputs to prevent XSS or injection attacks, implementing secure authentication mechanisms, and ensuring secure configuration.
Security testing:
Tools such as SAST and SCA are used to ensure secure code. Integrating these tools into the CI/CD pipeline ensures continuous checks and allows for automated flagging of vulnerabilities and coding errors.
Code reviews:
Regular code reviews — both manual and automated — ensure that agreed-upon best practices are followed.
Continuous monitoring, maintenance, and improvement:
Even after deployment, monitoring for security issues and updating as needed ensures that software stays secure and resilient across its lifecycle.
All of these measures help organizations build and deploy applications that align with both business needs and security best practices. As we’ll see, the impact of using traditional SDLC versus secure SDLC is well worth the effort.
The Benefits of SSDLC
Now that the importance of SSDLC from a technical perspective is understood, what can a secure software development lifecycle bring to the table in business-benefit terms? Here are just some of the key payoffs of implementing SSDLC:
- Reduced costs: Identifying and addressing security issues earlier in the SDLC is significantly more cost-effective than later in development, especially post-deployment.
- Improved software quality: Better modeling, increased testing, and enhanced security all ultimately lead to more robust, better-quality software — and enhanced customer trust.
- Faster development times: By baking security in from the beginning, SSDLC can actually help reduce time spent resolving issues, which improves project management and helps security be part of the accelerated SDLC rather than being a roadblock.
- Mitigated risk: Embedding security at every stage of the SDLC minimizes vulnerabilities – reducing the likelihood of successful cyberattacks or data breaches.
- Improved supply chain security: By reducing insecure coding practices and rooting out security flaws before they can become a problem, SSDLC helps reduce the risk of introducing and reintroducing vulnerabilities into the software supply chain.
- Compliance support: Compliance and security are two sides of a risk management and mitigation coin. The clarity and planning that support SSDLC can help security teams also ensure their projects meet broader standards and requirements.
- Proactive security: SSDLC is, by definition, a proactive approach to ensuring security. Mitigating vulnerabilities before they can become an issue helps reduce the attack surface and enhance overall security posture against dynamic, emerging threats.
OX AppSec Excellence: Keep Security at the Core of the SDLC
Traditionally, AppSec teams often wait until the “testing stage” before beginning security-related tasks. The problem with that is that the later a vulnerability or other issue is found, the more difficult (and expensive) it is to fix. That’s why SSDLC is important: it integrates security testing across every stage of the SDLC, from code to cloud, allowing organizations to resolve issues before they become a problem and before they can have a wider impact on the software supply chain.
OX Security’s AppSec Platform sets a new standard for software supply chain security. OX Active ASPM enables organizations to accelerate application development, deliver secure software on schedule, and continuously monitor software supply chain security by automatically avoiding vulnerabilities during development — and repairing them post-product.
See for yourself – book a demo or start a free trial today and see how you can improve your AppSec and reduce AppSec risk.
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