IAST vs. DAST – Exploring the Differences

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Application Security Testing (AST) techniques help make an application resilient to security vulnerabilities by identifying potential threats in the application source code. Modern security testing mechanisms are determined by how they operate and inspect application vulnerabilities. These include Static Application Security Testing (SAST), Dynamic Application Security Testing (DAST), Interactive Application Testing (IAST), and Runtime Application Self-Protection (RASP), among others.

This article compares the IAST vs. DAST testing approaches, how they differ, and the benefits of using these techniques for actionable and scalable application testing.

What is IAST?

Interactive Application Security Testing (IAST) helps identify application runtime issues by interacting with its core functionality. The testing mechanism deploys sensors and agents in the application’s runtime environment for iterative, real-time detection of exploitable vulnerabilities while pinpointing the relevant lines of code and providing actionable remediation advice. 

Traditional testing methods only provide a snapshot of an application’s security posture, making them unsuitable for testing modern, agile software development environments. In contrast, IAST employs a continuous, hybrid testing approach that merges static and dynamic testing techniques to perform real-time analysis of application flaws.

Since agents and sensors are running from within the application, they are considered to extract insightful data to help detect malicious activity and vulnerabilities in code. This data includes:

  • The entire application code base
  • Data flow and runtime control information
  • Configuration options and information
  • HTTP requests and responses
  • Frameworks, libraries, and other components used in development workflows
  • Backend connection data

Effective implementation of the IAST testing process typically undergoes the following stages:

  • Tool selection – Identifying appropriate security testing tools that can perform comprehensive scans based on programming languages used to develop the application
  • Configuring the testing infrastructure – This involves setting up access configurations, authorizations, and other integrations required, including alerts and issue-tracking software
  • Security tool customization – Security experts should fine-tune the testing tools to suit the application’s needs. Fine-tuning involves integrating the tool into the production environment, configuring custom reports, and configuring dashboards to track test results.
  • Adding applications – Requires security professionals to connect testing tools with the application stack for functional testing
  • Test result analysis – Analyzing and triaging scan results to remove any false positives while identifying and remediating any runtime issues detected.
  • Training and awareness – Post analysis of results, security and development teams should document their findings in actionable reports for cross-organization collaboration. This stage also requires organization-wide training to incorporate mitigation actions and the adoption of security controls into the development process.

Benefits of IAST

Through its broad range of advantages, IAST outperforms other security testing approaches. These include:

Low rate of false positives

IAST tools can perform large-scale scans of requests and responses for rapid triage and assessment. These tools provide accurate scans at scale with a low rate of false positives by pinpointing the exact lines of code that contain common and complex vulnerabilities. The detailed assessment report further enables security teams to perform comprehensive code analysis and prioritize security risks for remediation.

IAST enforces “shift-left” security

IAST functional testing is often performed during the staging phase of the development cycle, which allows security professionals to detect issues earlier, reducing mitigation costs and post-deployment issues. IAST tools can be configured to run within the development stack, allowing them to return test results as soon as the modified application source code has been compiled, enabling the instant detection and remediation of runtime vulnerabilities.

Seamless CI/CD integration

Most IAST tools can be integrated through web APIs with the commonly used build, test, and QA frameworks without requiring extensive configuration or tuning. The IAST mechanism also extends the DevSecOps philosophy by enabling seamless reporting, visualization, and issue tracking of security vulnerabilities

IAST enables rapid, less-costly code fixes

The IAST testing mechanism offers access to runtime information and code components, allowing developers and security teams to quickly identify the root cause of the problem. As IAST is performed during the earlier stages of the development lifecycle, the result includes insightful data on application flaws to help with quick mitigation before they make it to the production environment. This reduces the costs of remediating vulnerabilities as they are eliminated before malicious actors can exploit them for orchestrating attacks.

Complete code coverage

Unlike DAST and SAST, IAST operates by having access to runtime information, application source code, memory/stack trace information, libraries, frameworks, and various other components used in the deployment. IAST also uses agents and sensors to perform continuous security checks to detect vulnerabilities through all phases of code changes and different deployment environments.

Easy to deploy and use

Most IAST tools are ready to start testing out of the box. As these tools do not need extra configuration options, security teams can begin scanning for application flaws immediately after installation. IAST tools are also highly scalable and work well with applications of any size, helping to identify numerous attack vectors with minimal human effort.

What is DAST?

Dynamic Application Security Testing examines an application runtime by triggering simulated tests through the front end. As a black-box testing method, security professionals designing and performing DAST scans require no knowledge of the source code, system design, or the application’s internal interactions.

DAST tests are typically orchestrated by mimicking malicious actors, often by sending sample attack payloads to return results not expected by development and security teams. The approach is considered effective in testing third-party component vulnerabilities that cannot be identified using static code analysis techniques.

Benefits of DAST

Benefits of dynamic testing include:


All DAST tests work in the same pattern, regardless of the tested application. These tests are constructed using known vulnerabilities used for security breaches. With DAST tools, security teams do not have to write separate tests for each application, which keeps the security testing process from slowing down application development cycles.

Uncovers real-world exploits

The dynamic analysis simulates the attacker’s approach, subsequently allowing development teams to analyze how the application behaves in a real environment. Performing these tests in earlier stages of the software development life cycle enables proactive mitigation of exploitable vulnerabilities, helping to reduce an application’s attack surface.

Does not require access to the source code

DAST scans do not need access to the source code or internal implementation of the application, allowing them to expose a broader range of vulnerabilities compared to static tests. The scans efficiently uncover vulnerabilities such as configuration errors and failed authentication attempts, which typically go undetected through other forms of testing.

IAST and DAST – How Do They Differ?

DAST is a non-functional testing technique in which security experts analyze the application through the front end. DAST is a black-box approach, where the testers do not have access to the application source code and detect potential vulnerabilities through simulated attacks.

While both IAST and DAST security testing approaches rely on dynamic analysis of source code to identify security flaws, there are fundamental differences in their operating patterns.

Here is a quick comparison of the IAST and DAST testing approaches.

Testing approachBlack-box testingGray-box testing
Testing VelocitySlower on account of additional configurations required to integrate with CI/CD.Fast and immediate testing and remediation of issues through embedded agents.
Actionable vulnerability reportsOffers minimal guidance to fix the vulnerabilities discovered.Provides real-time results and actionable reports on where to find and how to fix the vulnerabilities identified
Code coveragePerforms application-level vulnerability scanning by running simulated attacks and uncovering runtime vulnerabilities.Performs comprehensive tests through both dynamic testing and static code analysis. Uncovers runtime vulnerabilities and integrations, third-party libraries, and source code flaws.
Test frequencyPeriodic testing requires security experts to create tests and relies on a dedicated testing environment.Runs continuous iterations of test cases while integrating seamlessly with other existing functional testing processes.


What is the difference between IAST and RASP?

Runtime Application Self Protection (RASP) is a security-hardening approach to application runtime environments by intercepting all calls to the system and ensuring they are secure. RASP is a self-sustainable testing strategy that identifies a potential flaw, obtains additional contextual information about the application’s current state, and responds to malicious activity within the production environment. RASP operates with a few fundamental differences compared to the IAST testing strategy. These include:

  • While IAST identifies security vulnerabilities and offers remediation advice, RASP tools go a step further and perform automatic mitigation of identified attack payloads.
  • IAST focuses on runtime error detection and mitigation. On the other hand, RASP is geared toward the identification and remediation of malicious attacks.

What are the key features to consider when choosing an IAST tool?

Features to look for in an IAST tool include:

  • Web APIs that enable continuous integration of security tests into the development pipeline
  • Compatibility with any existing testing approaches, including traditional testing methods
  • Real-time analysis with low false-positives
  • High scalability
  • Automated deployment models
  • Native support of different architecture patterns, such as microservices, cloud-native, monoliths, etc.

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