Securing the Foundations:
How Source Code Maintainability
Empowers DevSecOps

Alex T. Zacharopoulos
Head of Delivery and Innovation | code4thought
In the rapidly evolving landscape of software development, the significance of software security has escalated, particularly in critical infrastructure sectors like manufacturing, transport, and financial services, where regulatory compliance is stringent. The enforcement of standards such as the Network and Infrastructure Security Directive (NIS2) and Digital Operational Resilience Act (DORA) has brought software security assurance and compliance into sharp focus. Software quality assurance, particularly in code quality and software maintainability, emerges as a critical factor.
This approach to software security hinges on our experience. Having worked for the past 20 years on software maintainability and security projects for numerous large-scale systems, the belief that the bedrock of robust application security (AppSec) lies in the maintainability of source code has been in our core from day one. Based on what we have experienced, we will share how fostering high-quality, maintainable code is not just a matter of software system evaluation, but a strategic move toward comprehensive software security compliance.

The Rising Tide of Software Security Regulations

The domain of software development has seen a significant shift with the advent of regulations emphasizing software security. NIS2 and DORA regulations underscore the need for a meticulous software risk evaluation to ensure adherence to these standards.
As critical infrastructure industries rely heavily on legacy systems, these regulations translate into a pressing need for systems modernization to transform them into secure and compliant platforms. This transition is a compliance exercise and a strategic move toward enhancing software quality and enforcing the commitment to risk management for software projects.
Studies and industry reports reflect this trend. For example, a survey by PwC revealed that most UK-based financial services firms increasingly boost their IT and security spending to improve their ability to respond to cyber threats. Another report from IDC shows that the total European cybersecurity spending will grow 10.6% in 2023, driven by the need for data protection and regulatory compliance. Finally, Gartner forecasted worldwide spending on security and risk management would grow 11.3% in 2023, with application security spending demonstrating a 24.7% growth.
This uptick in investment directly responds to the heightened regulatory environment and its implications for software development practices.

Understanding Source Code Maintainability

In software engineering, maintainability is a cornerstone of software quality. It refers to the ease with which a software system can be modified to correct faults, improve performance, or adapt to a changing environment. This aspect of software quality assurance has been proved to be critical in practice for several reasons:
  • Readability and Code Quality: High code quality, signified by readability and consistency, is essential for effective cybersecurity.
  • Scalability and Software System Evaluation: A maintainable codebase allows for easier adaptation to new security requirements, an essential aspect of software system evaluation.
  • Consistency and Software Risk Evaluation: Adhering to consistent coding standards is crucial in software risk evaluation, reducing the likelihood of security vulnerabilities.
In short, maintainable code is not merely a convenience; it is also a fundamental aspect of security in software development, as it is inherently more secure, more adaptable and simplifies risk identification and mitigation.
Let us consider the following cases, that we have met in real life quite a few times:
  • When major financial institutions overhauled their legacy systems, focusing on improving code maintainability, it significantly reduced the number of security incidents, as developers could more quickly identify and address vulnerabilities.
  • If we compare software projects, we can realize that projects with higher code maintainability scores experience fewer security breaches and faster resolution times for the breaches that did occur.
In this interwoven landscape, organizations can better position themselves to respond to the dynamic challenges of software security by prioritizing code maintainability.

Technical Debt and Its Impact on Security

Technical debt in software development encapsulates the extra cost associated with choosing an easy, often quicker solution over a better approach that would take longer. It’s akin to financial debt: easy to accumulate but burdensome over time. This translates to code that is quick to implement but may be hard to maintain, change, understand, or extend.
Technical debt poses significant risks to software security:
  • Rushed or suboptimal coding practices can lead to security flaws.
  • Excessive technical debt can make it challenging to implement new security measures or update existing ones, hindering the effectiveness of Application Security initiatives.
  • Keeping up with the latest security standards and regulations becomes more challenging as technical debt grows, potentially compromising software security compliance.
Mitigating technical debt is crucial for secure software development. Regular refactoring and prioritizing high-quality, maintainable code can significantly reduce technical debt. Continuous software quality assurance processes ensure that technical debt is identified and addressed promptly, maintaining the security integrity of the software.

Implementing a Successful DevSecOps Program

DevSecOps represents a paradigm shift in software development security. Stop doing security the right way is our slogan. Cybersecurity has to be integrated into every stage of the software development process rather than treating it as an afterthought. A successful DevSecOps program begins with establishing a foundation of high-quality, maintainable code. It also requires a cultural shift where every software engineer is aware of and committed to software security guidelines, such as the ones described by OWASP. Regular training and updates in the latest security practices are vital.
Based on these foundations, we believe that the following best practices for DevSecOps implementation are essential:
  • Embed security considerations in every phase of software development, from planning to deployment.
  • Utilize tools for automated testing and monitoring to ensure continuous application security.
  • Foster a collaborative environment where developers, security professionals, and operations teams work together towards a common goal of secure and maintainable software.


The intersection of software maintainability and software security is a strategic imperative. Maintaining high-quality, readable, and adaptable code is beneficial for meeting regulatory requirements and instrumental in establishing a robust software security posture. Implementing a successful DevSecOps program hinges on this principle—integrating software security assurance into every aspect of the development process.
As the demand for secure software solutions continues to rise, businesses must recognize the critical role of software maintainability in achieving their security objectives. By focusing on developing maintainable code and embracing the principles of DevSecOps, organizations can enhance their software security compliance and pave the way for more innovative, resilient, and successful software systems. In this dynamic digital era, securing the foundations of our software systems with maintainable code is not just a best practice—it’s a necessity.