On Out-of-band Application Security Testing (OAST)

6 min readSep 23, 2024

OAST has become a key method in cybersecurity, especially in DevSecOps. Traditional methods like SAST and DAST are good at spotting common vulnerabilities but often miss the more complex, tricky threats. That’s where OAST steps in. Instead of focusing on the app, OAST looks at what’s happening outside it — how it interacts with other systems and third-party services.

https://portswigger.net/burp/application-security-testing/oast

This helps it find hidden security issues that other methods might miss. In this article, we’ll explore OAST, why it’s important in today’s security practices, what it’s good at, where it has weaknesses, and how it works within CI/CD pipelines. After the conclusion of the article, I will share a link to a platform that explains these processes in detail.

A Modern Security Testing Paradigm

OAST takes a different approach compared to the usual testing methods because it focuses on what’s happening outside the app’s normal flow. This allows it to catch vulnerabilities that come from things like external services, integrations, or components. OAST is useful in a few important ways. It can help find data leaks by checking if your app is sending information to places it shouldn’t.

I gathered here the basic concepts of OAST

It’s also good at spotting security problems by looking at how long your app takes to respond. Plus, it keeps an eye on how your app connects with things like DNS or other outside services, making sure sensitive data isn’t accidentally shared. These features make OAST a great tool for catching hidden security risks. OAST does not just stop at the app itself — it can also uncover issues with third-party components, network misconfigurations, or even insecure cloud storage. The main idea here is that apps often depend on a lot of external systems, and attackers can take advantage of those dependencies.

OAST Tools and Integration with SAST

While OAST is a new and unique way to test for security issues, it works well when combined with traditional tools like SAST, which focuses on scanning your source code for vulnerabilities without running the app, while OAST digs into the external interactions. Using both together gives you a more complete view of any potential security threats. Different programming languages have their tools that can work with both OAST and SAST. Here are a few examples:

JavaScript: RetireJS and npm audit help find vulnerable dependencies in JavaScript packages

Python: Safety checks for vulnerabilities in Python project dependencies

Ruby on Rails: Bundler audit looks for outdated or risky libraries in Ruby projects

PHP: Composer helps with managing dependencies, although its security capabilities are a bit limited

Java: OWASP Dependency Checker is great for scanning dependencies and finding vulnerabilities in Java apps.

Using a mix of these tools, you can cover more ground and keep your app secure from all angles.

OAST in CI/CD Pipelines

In DevSecOps practices, it’s super important to have security testing built right into your CI/CD pipelines. This helps you spot security issues early, saving you from bigger problems later on. Adding OAST into your CI/CD pipeline has a lot of advantages, but it’s not without its challenges either. Here are some simple tips to make OAST work in your CI/CD:

Keep it quick: Security tests should be fast — anything longer than 15 minutes is going to slow down your deployments
Use tools with API support: Tools like OWASP Dependency Track that come with API support are perfect for making everything run smoothly
Pause when needed: If there’s a serious security issue, your pipeline should automatically stop the deployment process
Go step by step: Roll out different tools and languages in stages to avoid overloading your system all at once
Stay focused: Fine-tuning your tests to target specific areas and cutting down on false positives will help everything run more efficiently.

By integrating OAST into your CI/CD, you’ll be catching vulnerabilities in third-party components, your code, and even Docker containers before anything reaches production.

Challenges and Solutions in Implementing OAST

OAST has some great benefits, but it also comes with challenges. Sometimes you’ll find vulnerabilities with no available fix, forcing teams to either create a manual patch or take a risk. Older systems can be tough too, as updates may not be available, leaving teams to decide whether to update or not. False positives can also be a hassle, where OAST flags safe components as risky, requiring manual checks.

Dependencies can get tricky when they rely on other dependencies, making it hard to find vulnerabilities. Lastly, updating to secure versions can break parts of your app, which needs careful handling. The best way to tackle these challenges is with a risk-based approach. It’s about balancing the risk of leaving a vulnerability unfixed against the effort and potential issues of fixing it. It’s all about making smart decisions and keeping things in perspective!

Strengths, Weaknesses, Opportunities, and Threats (SWOT) Analysis

When you look at OAST, it’s clear where it excels and where it faces a few hurdles. One of its biggest advantages is how easy it is to set up, especially for analyzing third-party components. Plus, it’s pretty good at cutting down on false positives compared to traditional methods like SAST, which means you spend less time dealing with unnecessary alerts. On the flip side, OAST relies a lot on external checks, which makes it less effective for scanning internal or custom code.

But there’s a big opportunity to improve this, making the tools more useful for internal security. The biggest challenge, though, is the increasing complexity of software. As dependencies stack up, it gets harder to trace vulnerabilities deep within those layers, which can make thorough security testing a bit tricky. So, while OAST has its strengths, it’s important to be aware of these limitations to get the most out of it.

Taking DevSecOps to the Next Level

If you’re ready to dive deeper into everything we’ve talked about — like securing your CI/CD pipelines, working with tools like OAST, SAST, and DAST, and building solid DevSecOps practices — the Certified DevSecOps Professional course from Practical DevSecOps is the perfect starting point.

This course is super hands-on, with over 100 guided exercises that teach you how to build and maintain secure pipelines. You’ll learn all the tools and techniques needed to spot vulnerabilities early, automate security processes, and keep your systems secure using tools like OWASP Dependency Checker, ZAP, and more. It covers everything from the basics of DevOps to advanced security practices, including Software Component Analysis, Infrastructure as Code, and how to embed security into your CI/CD pipeline fully. You’ll also get practical experience using popular platforms like GitLab, GitHub, Jenkins, and Ansible to create secure pipelines for real-world applications.

The best part? You don’t need to be a DevOps expert to take this course. It’s designed to guide you through everything step by step. By the end, you’ll know exactly how to improve your organization’s security processes and implement DevSecOps best practices. Ready to get started? Check out the course and sign up here: