Mission InfoSec

DAST That Doesn’t Suck: A Practical Guide

The Product Security Playbook

Read time -

~6 min read

Publish Date :

December 12, 2024

#010

DAST That Doesn’t Suck: A Practical Guide

Dynamic Application Security Testing (DAST) often feels like a heavy lift—difficult to implement and expensive to maintain. But done right, it can be a valuable tool in your security arsenal. In this issue, we’ll break down how to implement an effective DAST program that avoids common pitfalls and delivers results.

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Skipping DAST altogether can leave gaps in your security program. Those gaps translate into low-hanging fruit for hackers and trivial bug bounty submissions. A well-executed DAST program can save your team time, energy, and headaches by catching these vulnerabilities before hackers and security researchers do.

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Unfortunately, many teams give up on DAST because of the challenges involved.

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Why Teams Struggle With DAST

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Here are the three main reasons organizations find DAST challenging:

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Complex Configuration and Maintenance - DAST tools require a live application to scan, which means dealing with infrastructure quirks and setup headaches. Authentication flows, environments, and network configurations can all add layers of complexity that make getting started feel like climbing Everest.
False Positives and Negatives - DAST tools can sometimes feel like that friend who’s either overreacting or missing the point entirely. False positives waste your team’s time, while false negatives give you a false sense of security. Understanding what your tool excels at—and where it falls short—is key.
Integration Challenges - DAST tools don’t always play nice with your existing workflows. Without careful planning, they can feel like an obstacle rather than an enabler, especially for teams without a dedicated security engineer to guide the effort.

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Here’s the good news: you don’t have to tackle everything at once. With the right approach, you can roll out a DAST program that works for your team and grows over time.

Step 1: Start Small with an MVP

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Rolling out a DAST program doesn’t have to be all-or-nothing. The perfect program takes time to build. Instead, focus on starting small and demonstrating value as you go. Here’s how:

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Use Open Source Tools Like ZAP

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ZAP (Zed Attack Proxy) is a free and powerful tool with excellent documentation. It includes features for automating authentication flows and integrates well with CI/CD pipelines through pre-built Docker images and GitHub Actions.

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Automate Early

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Start with a single, critical application and automate scans in your CI/CD pipeline. By focusing on one use case, you can iron out the kinks and build a model for scaling to other applications.

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Small wins build momentum. Showing value early makes it easier to secure the resources you’ll need to scale.

Step 2: Choose the Right Tool for Your Environment

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Not all DAST tools are created equal, and your favorite pentesting tool might not cut it for automated testing. I learned this lesson the hard way.

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After selecting a trusted pentest tool for our DAST program (because it was cheaper and familiar), we discovered it couldn’t handle our authentication sequence. Months of frustration later, we had to go back to the drawing board and renegotiate with the original vendor.

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Here’s how to avoid this trap:

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• Test tools in the same environment where they’ll run.

• Run trial scans against your actual applications.

• Thoroughly integrate with your existing tools before committing.

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Think you’ve done enough testing? Double it. Issues found during the sales phase are solvable. Issues found after purchase are expensive mistakes.

Step 3: Plan for Gaps

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DAST tools aren’t silver bullets. They excel at some things (e.g. injection vulnerabilities) but struggle with others (e.g. authorization flaws). It’s your job to understand these gaps and plan accordingly.

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For example:

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Authorization Flaws: Most DAST tools aren’t aware of user roles and permissions. Advanced configuration can help, but it’s no substitute for complementary testing strategies.
Logic Flaws: DAST tools don’t understand the logic flows of your application. Even if they did, they generally lack the creativity of an experienced penetration tester.

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By knowing your tool’s limitations, you can design a security program that leverages DAST for what it’s good at while covering its blind spots with other strategies like static analysis and manual testing.

finally {

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Building a successful DAST program doesn’t have to be overwhelming. By starting small, choosing the right tools, and planning for gaps, you can create a program that fits your team’s needs and grows over time. DAST isn’t just a tool—it’s _still_ an important part of a comprehensive security program that protects your products and your customers.

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}

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Diving Deeper

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Here are some resources to help you get started:

• OWASP ZAP Documentation

• OWASP DevSecOps Guideline

• OWASP Benchmark

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DAST That Doesn’t Suck: A Practical Guide

DAST That Doesn’t Suck: A Practical Guide

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