You're dealing with legacy code security issues. How can you innovate without compromising safety?

First things first. And you need to identify assets that you will process risks for. And divide assets to different sectors and statuses and then you go for risks.

Identify Vulnerabilities: Start by conducting a comprehensive risk assessment of the legacy codebase. This involves identifying potential security vulnerabilities, outdated dependencies, and areas where the code does not comply with modern security standards. Tools like static code analyzers and vulnerability scanners can help detect these issues. Prioritize the identified risks based on their potential impact and likelihood. This prioritization allows you to focus on the most critical vulnerabilities that could compromise the safety of your application. Assess Impact of Changes: Before making any changes, assess the impact on the existing system. Understand how modifications might affect functionality, performance, and security.

Incremental Refactoring: Refactor the legacy code incrementally rather than attempting a complete overhaul. Small, manageable changes reduce the risk of introducing new bugs or security flaws. This approach allows for continuous improvement of the codebase while maintaining system stability. Focus on cleaning up the most problematic areas first. Refactor code to improve readability, reduce complexity, and adhere to modern coding standards, all of which contribute to better security. Isolate Legacy Components: Where possible, isolate legacy components from the rest of the system. This isolation minimizes the risk of security issues spreading across the entire application.

Refactoring is a fair process but we also don't forget about code reviewing practice. So that later we don't have to refactor again and again. Also other best practices in coding and testing should be applied.

Adopt Secure Coding Practices: Integrate secure coding practices into your development process. This includes validating inputs, using safe libraries, avoiding hard-coded secrets, and ensuring proper error handling. Secure coding helps prevent common vulnerabilities such as SQL injection, cross-site scripting (XSS), and buffer overflows. Implement Security Controls: Add security controls such as encryption, authentication, and authorization mechanisms where necessary. Even in a legacy system, these controls can mitigate risks and enhance the overall security posture.

We should also integrate DevSecOps practices into our coding process. We use SAST and DAST to test our code. Also we should never forget about segmentations on every step and about supply chain threats.

CI helps us test, build and get prepared for next step that is CD. The more experienced developer is the more steps are in CI process. This includes but not limited to: testing, building, security scanning etc.

Automate Security Testing: Implement automated security testing as part of your continuous integration (CI) pipeline. Tools like SAST and DAST can be integrated to scan code for vulnerabilities during each build, catching issues early in the development cycle. Frequent Builds and Deployments: Adopt a continuous deployment model where changes, once tested and approved, are deployed frequently. This approach allows you to introduce security improvements gradually without waiting for large, infrequent releases.

Security practices should be integrated at all steps of DevOps processes. We should improve continuously our skill and also train our team what we learned. And explain and integrate new solutions too.

Educate the Team: Invest in security training for your development team. Understanding the latest security threats and mitigation techniques is crucial for writing secure code. Regular training sessions, workshops, or certifications can help keep the team up-to-date. Foster a security-first mindset across the team. Encourage developers to think about security at every stage of development, from design to deployment, ensuring that security considerations are baked into the process. Promote a Culture of Security: Create a culture where security is a shared responsibility. Encourage open discussions about security concerns and provide a platform where team members can share knowledge and best practices.

Plan for Gradual Upgrades: Rather than abandoning legacy systems, plan for gradual upgrades. This can include updating dependencies, rewriting critical components, or migrating to more modern frameworks. Each upgrade should be carefully planned to minimize disruptions while improving security. Monitor and Maintain: Continuously monitor the legacy system for new vulnerabilities. Even after upgrades, it’s essential to keep an eye on the system’s performance and security. Regular maintenance, patching, and updates are critical to keeping the legacy system secure.