Dynamic Application Security Testing (DAST) Explained

What is DAST?

Dynamic application security testing (DAST) is a method that evaluates an application's security by testing it at runtime without access to its underlying source code. By focusing on runtime behavior, DAST allows organizations to detect vulnerabilities that may not be apparent through static analysis alone.

While static application security testing (SAST) scans the source code of an application to uncover vulnerabilities before deployment, DAST uses automated tools to simulate attacks on the live application, assessing how effectively it responds. When integrated with existing CI/CD pipelines, this dynamic testing approach can catch vulnerabilities before the application is deployed to production. Adopting DAST can accelerate deployment velocity while improving overall security coverage.

In this article, we’ll look more closely at what DAST is and how it works, along with some of the challenges its usage brings.

How DAST works

DAST tools run against a deployed application in a staging or test environment. These tools automate the simulation of attacks like SQL injection or XSS through the application’s exposed interfaces. DAST tests application behavior by sending malicious inputs and analyzing responses, and it does so without needing access to the source code.

Differences from static application security testing (SAST)

SAST analyzes source code to identify vulnerabilities like outdated libraries, insecure code, or hard-coded credentials. Conversely, DAST focuses on runtime behavior, examining the application when its full functionality is active.

DAST tools detect issues that SAST might have missed, such as authentication bypasses, weak passwords, and vulnerabilities in components that only surface when the application runs.

DAST and SAST are complementary tools, together providing comprehensive security coverage that addresses both runtime vulnerabilities and code-level weaknesses.

Types of vulnerabilities detected by DAST 

DAST is highly effective at detecting vulnerabilities that may threaten an application's security. Among the most common vulnerabilities identified by DAST are:

• SQL injection
• Cross-site scripting (XSS)
• Unvalidated redirects

Unvalidated redirects purposely mislead users to unsafe locations and expose them to phishing or malware. .

Additionally, DAST excels at uncovering business logic flaws—issues that may not be evident in the code but emerge from the application’s real-world functionality. Typically, without DAST, these flaws are uncovered by end users, potentially leading to undesirable actions or vulnerabilities.

DAST in the SDLC

A shift-left security approach promotes the focus of security testing earlier in the software development life cycle (SDLC) rather than relegating security concerns only to the deployment phase and beyond. DAST contributes to a shift-left approach because it can provide efficient detection and remediation of vulnerabilities before deployment, often in staging, QA, or testing environments.

Automating security checks within CI/CD pipelines enhances development productivity, as vulnerabilities are identified and prioritized in real time. DAST can integrate with CI/CD to run security scans automatically on every code commit or build. This automation can yield immediate feedback to developers, allowing for swift issue remediation before deployment.

DAST also supports a more efficient assignment of vulnerability remediation to the appropriate developer or teams, ensuring that issues are quickly tracked, assigned, and resolved—without the need for manual intervention.

Challenges and limitations of DAST

While DAST can greatly improve the security of applications, it also comes with its own set of challenges and limitations.

Irregular results

DAST tools require proper configuration to simulate attacks effectively based on the application’s context, including proper handling of authentication and session management. Regular tuning can help minimize false positives and negatives by aligning scan parameters—such as timeout limits, request throttling, and authentication configurations—with the specific needs of the application and its environment.T.

Additionally, it's important to review scan results and refine vulnerability filters by denylisting certain vulnerabilities that are either less relevant to the application or identified as persistent false positives. This can minimize noise and optimize the analysis process to focus on genuine threats to security.

Performance issues

Due to the thorough testing of all potential vulnerabilities across the entire application, comprehensive DAST scans can be time-consuming. This can cause delays in pipeline execution and extended deployment schedules. Misconfigured scan settings can also overwhelm resources, leading to potential downtime in the environments where it is used. 

Optimize scan configurations by focusing on incremental or targeted scans—instead of full scans—during development cycles. Tools like ZAP and Burp Suite scan specific areas, such as recently modified code or critical endpoints. Integrating DAST into CI/CD pipelines with tools like GitLab DAST allows you to run automated, incremental scans that identify vulnerabilities early without overloading resources.

Limited visibility

Even though the integration of DAST significantly improves security testing, it is possible to obtain an overstated picture of security while testing the application for vulnerabilities. For instance, DAST may struggle to fully assess applications behind complex authentication mechanisms, leaving potential vulnerabilities undetected. Regular penetration testing, which can uncover deeper, context-specific threats that automated scans might overlook, should complement DAST to ensure comprehensive security coverage. Using both these strategies offers better protection against security threats.

Protect your applications with comprehensive security

DAST is a powerful tool for identifying runtime vulnerabilities by simulating real-world attacks on a live application. This dynamic approach allows organizations to detect issues like SQL injection, cross-site scripting, and business logic flaws that may not be apparent through static code analysis alone. However, while DAST provides significant benefits, it also has limitations. False positives, false negatives, and difficulties with complex authentication mechanisms all impact the effectiveness.

Using DAST with other testing methodologies, such as SAST, Interactive Application Security Testing (IAST),  penetration testing, and Application Security Posture Management (ASPM) provides a comprehensive security approach that can surface vulnerabilities that DAST alone may miss. Additionally, fine-tuning DAST’s integration into CI/CD pipelines maintains security and efficiency, optimizing scan configurations and continuously refining vulnerability filters. By combining DAST with the above practices and other security measures, organizations can ensure more robust protection while streamlining development processes and minimizing disruptions.

If your organization wants to strengthen its application security, explore how CrowdStrike Falcon ASPM complements  DAST to provide comprehensive security coverage and minimize your application security risks.