Dynamic Application Security Testing (DAST): A Complete Guide

According to research by Statista, over 353 million individuals were impacted by data breaches and leaks in 2023 alone. Many of these breaches stem from vulnerabilities within software applications. What's even trickier is that some vulnerabilities, like misconfigurations and security policy violations, only become apparent when the software is up and running.

Dynamic application security testing (DAST) helps detect potential security vulnerabilities in software by mimicking how hackers might exploit weaknesses.

Understanding how DAST works can help you build and release secure software products faster. Here's everything you need to know.

What is DAST?

DAST is a type of application security testing that detects security vulnerabilities by simulating attacks against an application in its running/operating state. This black-box testing method examines the application from the “outside-in” by attacking it like a malicious user would. According to our State of Software Quality 2024 report, 45% of the software developers we surveyed are currently employing dynamic application security testing tools. 

Using DAST during the software development lifecycle enables teams to uncover vulnerabilities before their applications are in production. DAST is completely language agnostic and can be automated in a continuous integration/continuous deployment (CI/CD) pipeline, automated on a schedule, or run independently by using on-demand DAST scans.

DAST tools simulate how a user interacts with an application and generate reports on a wide range of security issues. How the application responds to these simulations helps determine whether it is vulnerable to a real-life, malicious attack.

Why Is DAST Important?

DAST helps identify vulnerabilities that might be missed by other testing methods, such as Static Application Security Testing (SAST), which analyzes code but doesn't involve running the application. DAST tools test applications in real-world scenarios, making it possible to find configuration and authentication problems or other runtime vulnerabilities that may impact your application’s functionality and security. It’s also a good method for preventing regressions and doesn’t depend on a specific programming language. As long as the application can be accessed through a browser, a DAST tool can typically scan it for vulnerabilities.

By proactively identifying and remediating vulnerabilities in running code, DAST tools can help organizations reduce the risk of data breaches, malware infections, and other security incidents.

DAST can also help you comply with standards or get certifications, like HIPAA or PCI DSS.

How Does DAST Work?

DAST tools work by actively interacting with a web application while it is running. The testing process typically involves the following steps:

1. Target identification: The DAST tool first scans the application's structure, including its pages, directories, and visible entry points. It then automatically navigates through the application, much like a search engine spider, to map out a comprehensive view of all accessible areas.
   
   
2. Vulnerability detection: Based on the identified structure, the DAST tool prepares a series of test attacks that simulate common security threats. The prepared tests are executed against the application, incorporating a range of inputs and user behaviors to probe for weaknesses.
   
   
3. Analysis of responses: The DAST tool monitors the application's responses to the simulated attacks, analyzing the outputs and behaviors for signs of vulnerability. It also scrutinizes the application's behavior, such as error codes, unintended outputs, or changes in state that could indicate a security issue.
   
   
4. Reporting: Once the analysis is complete, DAST tools generate detailed reports. These reports outline each discovered vulnerability and its severity level, and sometimes even offer suggestions for how to fix it.
   
   
5. Re-testing: After fixes are implemented, the DAST tool can be rerun to confirm that the vulnerabilities have been successfully addressed.

Pros and Cons of DAST

DAST tools are great for analyzing running applications. However, they cannot identify vulnerabilities in the source code. As with every technology, DAST has its pros and cons. Let’s take a close look at them.

Pros of DAST

• Low risk of reporting false positives: DAST identifies vulnerabilities on a running application by exploiting them. As such, it allows you to verify if a potential vulnerability is real and if it poses a threat to your application.
  
  
• Detection of runtime issues: DAST tools interact with a running application, enabling it to detect both compile-time and runtime issues.
  
  
• Works with every programming language: DAST is the only security testing method that isn’t programming language specific since it doesn’t look at source code. As such, if your application is implemented with a niche programming language, DAST may be your only choice.
  
  
• Uses regression testing: DAST makes it easy to check a previous vulnerability. If a vulnerability is reproduced, it can be added to the DAST test suit. As such, every subsequent release will include the same interactions that previously led to the issues.

Cons of DAST

• Doesn’t show problematic code locations: Since DAST doesn’t analyze code, it’s impossible to correlate the vulnerabilities and the exact line of code where they happened.
  
  
• Slower testing process: The requirements to execute and use a DAST tool can slow the testing process, even when using automated testing methods.
  
  
• Fixing vulnerabilities is more expensive: Since DAST needs a deployed application, it can only be performed later in the development lifecycle, increasing the cost required to fix the identified vulnerabilities.
  
  
• Doesn’t have complete code coverage: DAST tools analyze a running application, meaning they might miss vulnerabilities in parts of the code that are not executed.
  
  
• Manual testing may be needed: Sometimes, it’s impossible to automate your application’s execution and usage, so you’ll still have to test the application manually for every release.

5 Key Considerations for Choosing DAST Tools

With a variety of DAST tool options available, it is crucial to consider key factors to ensure that the tool you select aligns with your security and business needs. 

1. Vulnerability Detection

Evaluate the DAST tool's ability to detect a wide range of vulnerabilities. It should cover the OWASP Top 10 at a minimum and be capable of identifying both common and advanced threats. 

2. Comprehensive Coverage

Most organizations have multiple websites and applications, each containing multiple points of attack. Ensuring security across the board is paramount, as overlooking one area can leave others exposed. Ensure that the DAST tool can comprehensively cover your entire application and its dependencies. This includes not only the main application but also third-party libraries, APIs, and other components that could introduce vulnerabilities. A thorough assessment helps identify and mitigate potential security risks across the entire application stack.

3. Integration and Automation

To maximize efficiency, your DAST tool should integrate smoothly with your existing development workflow. Ideally, it should connect with your CI/CD pipeline, enabling automated scans as part of the development process. This way, vulnerabilities are identified and addressed early on, preventing them from reaching production.

4. Scalability and Performance

As your application grows in complexity and user base, your DAST tool should scale accordingly. The tool should efficiently handle increased testing demands without compromising performance. Look for a solution that offers flexible deployment options, such as on-premise, cloud, or hybrid, to accommodate your specific infrastructure needs.

5. Automated Compliance Reporting

If your organization needs to comply with regulatory standards or industry-specific requirements, choose a DAST tool that offers automated compliance reporting. The tool should generate reports for standards such as PCI DSS, HIPAA, GDPR, and ISO/IEC 27001, highlighting compliance status, vulnerabilities, and remediation actions. Automated reporting not only saves time but also ensures that you meet regulatory obligations and maintain a strong security posture.

DAST vs. SAST: How They Complement Each Other

DAST and SAST are fundamental components of software security, each offering unique advantages that complement each other when used together.

Scope of Testing

SAST is a white-box testing method that focuses on analyzing the source code and identifying potential vulnerabilities without executing the code. It scans the codebase, looking for issues such as SQL injection, memory leaks, and other known security vulnerabilities.

DAST, on the other hand, tests the application in a live environment by actively interacting with it during runtime. It simulates real-world attacks to uncover vulnerabilities that may only surface when the application is running, such as authentication weaknesses, input validation errors, and runtime configuration issues.

Timing in the Development Cycle

SAST is typically performed early in the development process, often during the coding phase or during code reviews. It helps identify and fix security issues at an early stage, reducing the likelihood of vulnerabilities making their way into the final product.

DAST is usually conducted later in the development cycle, after the application is deployed or in a staging environment that closely resembles the production environment. It helps validate the security of the running application and detects vulnerabilities that may have been missed during static analysis.

Automation and Integration

Both DAST and SAST can be automated and integrated into the software development lifecycle (SDLC) and CI/CD pipelines. This enables organizations to conduct regular security testing and identify vulnerabilities before software release, reducing the overall risk of security breaches.

Organizations can achieve a comprehensive security assessment of their applications by combining DAST and SAST, along with other security testing techniques such as dependency scanning, license analysis, and penetration testing. This multi-layered approach helps identify and mitigate a wide range of security threats, enhancing the application's overall security posture.

Use SAST and DAST for Comprehensive Security 

While DAST offers a powerful shield against real-world attacks, it's important to remember that true application security is a layered defense. The most effective approach combines the strengths of both DAST and SAST.

Automating DAST and SAST scans with CI/CD allows you to accelerate development time without sacrificing your application’s security.

We understand the value of a holistic security strategy, which is why we offer a range of security solutions designed to address all the critical aspects of application security. 

Ready to take your application security to the next level?