Security problems discovered shortly before release are expensive for a simple reason: by that point, many of the decisions that created them have already been made. The architecture is defined, components have been selected, APIs are connected, code has been written, infrastructure is configured, and the delivery date is approaching.
Finding a serious vulnerability at this stage does not just create a security problem. It can trigger redesign, rework, additional testing and difficult conversations about timelines.
Secure by design takes a different approach. Treating cybersecurity not as a final validation step but making it part of the decisions that shape software throughout its lifecycle.
This is increasingly important as applications become more interconnected and dependent on APIs, cloud services, open-source components and third-party platforms. Verizon’s Data Breach Investigations Report found that exploitation of vulnerabilities as an initial access vector increased by 34%, while third-party involvement in breaches doubled to 30%.
For technology leaders, the question is therefore not simply: “Did we test the application for security?”. A stronger one is: “Where did security influence the way we designed and built it?”
Secure by design starts before development
One of the easiest mistakes to make is to introduce security once developers begin writing code. By then, important choices may already be fixed.
Security should influence requirements and architecture first. Before development starts, teams should understand:
- What data the application will process
- Who should have access to it
- Which systems and third parties it will trust
- What would happen if a component were compromised
- Which regulatory or compliance requirements apply
- Which functions would create the greatest impact if abused
This is where threat modelling becomes particularly useful. Instead of waiting to discover vulnerabilities later, teams consider how an attacker could misuse the system while there is still time to change the design efficiently.
Build security requirements into the backlog
Security requirements often exist separately from product requirements. One team manages features, another manages vulnerabilities, and security appears as a parallel workstream. This separation can create problems.
If authentication, authorization, logging, encryption or data protection are necessary for a feature to be considered complete, they should be reflected in the same delivery process.
For example, a new customer portal requirement should not simply say that users can access account information. It should also define appropriate access controls, session behavior, sensitive data handling and auditability.
This helps avoid a situation where the feature is considered finished functionally and security work is added afterwards.
Give developers secure defaults
Secure development depends on people, but it should not depend on every developer remembering every security rule every time. Good engineering environments make the safer choice easier. It can mean:
- Approved libraries and frameworks
- Reusable authentication components
- Secure coding standards
- Predefined infrastructure templates
- Secrets management
- Dependency management policies
- Automated security checks inside development pipelines
This reduces the number of security decisions individual developers need to make repeatedly and also creates consistency across teams.
CISA describes the same idea through secure by default: products should be configured so that the safest practical settings are available without requiring customers or users to perform extensive hardening themselves.
The principle can also be applied internally. If secure patterns are easy to reuse, developers are less likely to recreate sensitive functionality independently.
Automate security checks where feedback can arrive early
Security automation is particularly valuable when it provides feedback while the developer still has the change in context.
- Static application security testing can identify certain coding weaknesses
- Software composition analysis can detect known vulnerabilities in dependencies
- Secrets scanning can prevent credentials from entering repositories
- Infrastructure scanning can identify insecure configurations before deployment
- Dynamic testing can identify issues once an application is running
None of these replaces security expertise, and no tool will find every problem. Their value lies in making repeatable checks part of normal delivery.
A developer who learns about a vulnerable dependency minutes after introducing it can fix it relatively easily. Discovering the same problem several months later may involve multiple applications and teams.
Do not turn security into a release gate that everybody fears
There is an essential balance here: adding security everywhere can improve resilience, adding approval everywhere can slow delivery dramatically.
If every change requires a manual security review, security teams become a bottleneck and development teams may begin treating them as the department that says no. Secure by design must produce the opposite effect.
Routine security decisions should be automated, standardized or delegated where possible. Security specialists can then focus their attention on areas where judgment genuinely matters.
For example, a routine API change may pass through automated checks and established architecture patterns. A new identity model, sensitive data flow or externally exposed service may deserve specialist review.
This allows security involvement to follow risk rather than bureaucracy. The objective is to integrate security into delivery without creating a second delivery process.
Test the assumptions that matter most
Secure development still needs active validation. A design may look secure on paper and behave differently once components interact. This is where practices such as vulnerability assessments and penetration testing come in.
Penetration testing can help answer questions that automated checks cannot fully resolve:
- Can an attacker combine several small weaknesses into a meaningful exploit?
- Can access controls be bypassed?
- Can one compromised account reach data it should not see?
- Does the application expose unexpected paths through integrations or configuration?
The most useful security testing is not disconnected from the development team. Its findings should feed back into architecture, coding standards and future development decisions.
If the same category of vulnerability repeatedly appears in penetration tests, the long-term solution is not to keep finding it. It is to understand why the development process keeps creating it.
Treat third-party components as part of your application
Most modern applications contain a significant amount of code the organization did not write.: open-source libraries, APIs, cloud services, development tools and external platforms can all introduce risk. So, secure by design needs to include the software supply chain.
Teams should know which dependencies they rely on, monitor them for known vulnerabilities and define how updates will be handled.
ENISA’s 2026 Threat Landscape emphasizes that growing digital dependencies are expanding the attack surface across European organizations. The security of your own code is only part of the picture, you also need visibility into what your application trusts.
Create clear ownership when vulnerabilities appear
No software will ever be completely free of vulnerabilities. What matters is what happens when one is discovered.
- Who assesses the severity?
- Who owns remediation?
- How quickly should different risk levels be addressed?
- What happens if the affected component belongs to another team or supplier?
- Can you identify which applications use it?
Without clear answers, vulnerabilities remain open simply because responsibility is unclear.
Secure by design therefore continues after deployment. Monitoring, vulnerability management, patching and incident response are part of maintaining the security assumptions made during development. Security is not finished when software reaches production.
Measure security as part of engineering quality
A strong view combines security with delivery and engineering metrics. You might track:
- Time to remediate critical vulnerabilities
- Vulnerabilities repeatedly introduced after remediation
- Percentage of critical applications covered by security testing
- Dependencies with known critical vulnerabilities
- Security findings detected before production
- Recurring weaknesses by development team or application
- Time required to respond to newly disclosed vulnerabilities
These measures help identify where the development process needs to improve.
The goal is to create software that generates fewer avoidable security problems.
Secure by design is a shared engineering responsibility
Security teams bring specialist expertise, but they cannot secure every application alone.
Developers understand the code, architects understand system boundaries, infrastructure teams understand environments, QA understands application behavior, and security specialists understand threats and controls. Good software security depends on those perspectives working together.
That may require dedicated security expertise inside a delivery team for a period of time, specialist support at critical stages, or external capabilities for activities such as penetration testing, vulnerability assessment and security consultancy. Count on our complete offering!
Frequently Asked Questions
What does secure by design mean?
Secure by design means considering cybersecurity during the design and development of software rather than adding security controls only after development is complete. Security requirements, architecture decisions, coding practices, testing and operational controls all contribute to the approach.
Is secure by design the same as shift-left security?
They are closely related, but not identical. Shift-left security focuses on moving security activities earlier in the development lifecycle. Secure by design is broader because it treats security as a fundamental design and engineering principle throughout the software lifecycle.
What security activities should be included in software development?
Depending on the application and its risk profile, activities can include threat modelling, secure coding standards, code analysis, dependency scanning, secrets detection, vulnerability assessment, penetration testing and security reviews for higher-risk architectural decisions.
Does secure by design slow down software development?
It should ultimately reduce avoidable delays. Adding security checks can require additional effort during development, but identifying problems earlier is usually easier than redesigning or remediating them close to release. Automation and reusable secure patterns also reduce friction.
Can DevOps teams implement secure by design without dedicated security specialists?
Development and DevOps teams can integrate many secure practices, but specialist expertise remains important for areas such as threat modelling, complex architecture decisions, penetration testing, incident response and higher-risk applications. The right balance depends on the organization and its risk profile.
How does penetration testing fit into secure by design?
Penetration testing validates how an application behaves against realistic attack techniques and can uncover weaknesses that automated controls may miss. Its findings are particularly valuable when they are used to improve future architecture, development practices and security controls.
