DAST

Dynamic Application Security Testing (DAST) is a category of security testing that analyzes a running application from an external perspective to identify potential security weaknesses. It focuses on exposed behavior rather than source code, and targets web applications and APIs by interacting with live endpoints.

DAST tools simulate attacks by sending a variety of crafted requests, crawling the application to map its attack surface and then probing for vulnerabilities such as injection flaws, cross-site scripting, misconfigurations, insecure authentication, and exposure of sensitive data. Tests are designed to reveal how the application behaves under attack and whether security controls are effective.

How it works: the tester configures the scan with scope and authentication, the tool crawls the site to discover endpoints, then executes a suite of tests against those endpoints, and analyzes responses for indicators of weakness. Findings are reported with evidence, risk rating, and remediation guidance. Some scans can run with user credentials to test authenticated areas.

Limitations: DAST cannot access source code or internal logic details, and some weaknesses require business logic testing or manual review. It can produce false positives and negatives, and results depend on the application’s current state and the test environment. Scans can cause performance impact and should be planned accordingly.

Relationship to other testing approaches: DAST complements SAST (static analysis of code) and IAST (hybrid analysis) and may be extended with RASP in runtime protection. It is commonly integrated into secure development workflows and continuous integration pipelines to enable regular regression testing in development, staging, and production-like environments.

By identifying vulnerabilities early in the software development lifecycle and providing actionable remediation guidance, DAST helps organizations reduce risk and comply with security standards that require testing of externally facing applications.