JavaScript has become the ubiquitous language of the web, powering dynamic features and interactive experiences. However, with this power comes, as you guessed, a big responsibility, and that includes security skills.

Malicious actors constantly explore new ways to exploit vulnerabilities in web applications, and JavaScript, due to its prevalence, is a frequent target. For JavaScript developers, possessing security skills is no longer optional. It’s a critical competency to safeguard user data, prevent application breaches, and maintain the trust of users.

By understanding secure coding practices, common web vulnerabilities, and how to fix them, developers can proactively build secure applications and contribute to a safer web environment.

So what are the security skills that JavaScript developers should master?

Security skills for Writing Secure Code

Security practitioners are often discussing security tools, but developers are the first line of defense when it comes to writing secure code and are mostly driven by meaningful conversations around secure coding practices, because code is a developer’s primary tool for building secure applications (right after coffee).

Here are some essential security skills for writing secure JavaScript code:

Secure Coding Practices

Understanding and applying secure coding principles like:

• Input Validation and Sanitization: Validate and sanitize all user input to remove potentially malicious characters or code before using it.
• Output Encoding: Encode data before displaying it to prevent XSS vulnerabilities. This includes escaping HTML, CSS, and JavaScript and is often handled by modern JavaScript frameworks like React, Vue.js, Svelte and others. However, developers should still be aware of the risks and understand the purpose of output encoding, in case they need to implement it manually for edge cases.
• Least Privilege: Grant code and users only the minimum permissions they need. To take a practical example, think about something as simple as defining a browser cookie’s domain attribute. If you set it to the root domain, it will be accessible by all subdomains, potentially exposing sensitive data and available to other applications under the same domain. Instead, set the domain attribute to the specific subdomain that needs access.

Threat Modeling

Identify potential threats and vulnerabilities early in the development process. Consider what data your application handles, where it comes from, and how it’s stored. Being mindful of these factors can help you anticipate potential security issues and design safeguards against them, especially if you’re able to detect these as early as during a code review or a pull request (earlier is better, but you’re probably not going to catch everything).

Secure Libraries and Frameworks

Choose well-maintained libraries with a good security track record and stay updated on their security patches. I’ve previously shared some Node.js security best practices for you to consider if you’re spending a lot of time around the Node.js runtime environment.

Adopt a Secure by Design Strategy

How these security skills help? By following secure coding practices, developers can write code that is less susceptible to common attacks like XSS, SQL injection, path traversal, command injection and code injection. In fact, we have studies show that our brains are wired around patterns, and by following secure coding practices, developers can build a mental model of secure code patterns that can help them identify and fix vulnerabilities more effectively.

Threat modeling helps by bringing together developers, security experts, and other stakeholders to identify potential threats and vulnerabilities early in the development process. Simply by having a healthy and fruitful discussion around potential security risks and how the application works, what input and output it expects, developers can design more secure applications and reduce the likelihood of costly security incidents down the line.

Lastly, using secure libraries and frameworks reduces the risk of introducing vulnerabilities through third-party code and ensures developers are following best practices for security, as was set by the library or framework maintainers.

Skills for Fixing Security Vulnerabilities

It would be great if we could ship software without any vulnerabilities, but the reality is that vulnerabilities, just like software bugs, are a fact of life in software development. The key is to identify and fix them quickly and effectively. This is where security skills for fixing vulnerabilities come into play.

Here are some essential security skills for fixing security vulnerabilities in JavaScript applications:

• Understanding Common Vulnerabilities: Familiarity with common web application vulnerabilities like XSS, CSRF, SQL Injection, and path traversal allows developers to identify and fix them effectively. For example, consider learning about protecting against common Node.js vulnerabilities to secure your Node.js applications.
• Security Testing Tools: Leveraging tools like static application security scanners (SAST) and dynamic application security testing (DAST) helps automate vulnerability detection. I’m a developer advocate at Snyk, so I’m biased towards Snyk’s tools, but I highly recommend checking out Snyk Code for static analysis. For dynamic application tests, I recommend StackHawk.
• Debugging and Root Cause Analysis: Strong debugging skills are essential for pinpointing the root cause of a vulnerability and developing an effective patch.

Beyond just maintaining security skills, it’s also helpful if developers can build a security-first mindset. This means thinking about security from the start of the development process, rather than as an afterthought. By integrating security into the development lifecycle, developers can proactively identify and fix vulnerabilities, reducing the risk of security incidents and ensuring a more secure application.

Another key aspect of addressing security vulnerabilities, beyond security skills themselves, is automation and culture which is often brought up in relation to DevOps practices. Mature DevOps adoption allow teams to automate their software delivery pipeline, including security testing, and foster a culture of collaboration and shared responsibility for security. This can help developers fix vulnerabilities faster and more effectively, and ensure that security is a priority throughout the development process. The book Accelerate by Nicole Forsgren, Jez Humble, and Gene Kim is a great resource for learning more about how DevOps practices can improve software delivery and security.

Concluding with additional tips

Stay updated on the latest web security threats and best practices by following security blogs, attending conferences, and participating in online communities. Many cybersecurity companies are happy to recognize security champions and provide them with resources to stay up-to-date on the latest security trends.

Also consider security from the beginning of the development lifecycle, not as an afterthought and take into account continuous integration and continuous delivery (CI/CD) pipelines that can be integrated with security testing tools to automate vulnerability detection and remediation.

By cultivating these security skills, JavaScript developers can significantly improve the security posture of their applications and contribute to building a more secure web ecosystem.