Dynamic Application Security Testing

How DAST Works

A DAST scanner crawls the application or reads an API definition to discover pages and endpoints. It then sends requests with modified inputs, such as injection payloads, unexpected values and manipulated headers, and watches the responses for errors, reflected input, timing differences and other signals that something is vulnerable.

What DAST Is Good At

• Runtime and configuration issues. Missing security headers, exposed endpoints, weak TLS and server misconfiguration.
• Language independence. It tests behavior, so it works regardless of how the app is built.
• Fewer theoretical findings. If a payload produces a vulnerable response, the issue is usually real.

Where DAST Falls Short

• Late in the cycle. It needs a running, deployed application.
• Coverage gaps. It only tests what it can discover and reach, which is hard for complex authenticated flows.
• Single-step testing. Most scanners test requests in isolation and miss attacks that chain several steps.
• Location. Findings point to a URL, not the line of code to fix.

DAST vs SAST vs Penetration Testing

SAST reads the code. DAST probes the running app with automated payloads. Penetration testing goes further by chaining weaknesses together and proving impact the way a real attacker would. Many teams use DAST for broad automated coverage and penetration testing for depth.

How Nullify Approaches Runtime Testing

Instead of single-request scanning, Nullify's AI pentest agent continuously attacks REST and GraphQL APIs with active, multi-stage exploitation, and each exploit is independently re-reviewed and reported with request and response pairs, screenshots and video. See how the Nullify AI pentest agent works.