What is Interactive Application Security Testing (IAST)?

Interactive application security testing (IAST) solutions help detect and remediate vulnerabilities in web applications, as part of an organization’s security testing toolset.

IAST involves using dynamic testing, also known as runtime testing, to monitor application performance. IAST solutions instrument applications during runtime, using specialized sensors, to collect operational data and analyze user interactions with the application. 

The IAST process can incorporate a combination of automated security tests, customized tests defined by the organization, or software composition analysis (SCA) to analyze open source components and find known vulnerabilities.

In this article:

How Do IAST Tools Work?

IAST tools deploy agents and sensors in the application during the post-build phase of the software development cycle. The agent works by observing the application’s performance and analyzing traffic flow. It maps external signatures or source code patterns to identify complex security vulnerabilities. 

IAST tools provide a dashboard or web browser that lets you view testing reports in real-time and use customized reports that suit your CI/CD pipeline. You can also combine IAST results with other issues tracking tools.

IAST vs SAST vs DAST

Static application security testing (SAST) is a white box method that checks your code for vulnerabilities and flaws. It involves scanning code at rest and searching for known errors or an established set of rules. During the scan, a human or an automated program scans static code instruction by instruction and line by line. 

Dynamic application security testing (DAST) is a black box method that checks running applications for security vulnerabilities and weaknesses. It involves looking for ways to attack the application without getting authorized access to the source code. A pentester or tool performing DAST simulates an external attack, typically by injecting or feeding malicious or faulty data to the tested software.

Related content: Read our guide to DAST vs SAST

IAST employs both DAST and SAST techniques to test the inner workings of the source code, usually while the application is in development. IAST does not simulate an external attack and does not scan the entire codebase. Instead, DAST checks functionality at specific predefined points to achieve faster testing times. As a result, IAST does not provide complete coverage.

IAST Benefits and Drawbacks

Here are notable benefits of IAST:

  • Scans code in production—SAST tools often result in numerous false positives. For example, reporting a line of code can that was already addressed in another area of the code. IAST scan code in production while focusing only on issues that truly matter.
  • Scans code in development—IAST can help shift security checks to the left by checking specific issues during development. For example, IAST tools with IDE integration can offer quick feedback on features in development. 
  • Quick remediation—IAST helps link issues with specific code locations. It enables developers to quickly click through an application to find specific problems and gain insights into quick remediation recommendations. 

Here are notable drawbacks of IAST:

  • Programming-language dependent—IAST tools are often bound to specific technologies that may not fit your scenario. Additionally, some tools may require changing your code to include the vendor’s sensor modules.  
  • Time intensive—IAST requires building and executing the tested application, which takes more time overall. If you use IDE plugins, you can leverage the quick feedback to catch issues during development. However, it can take longer when building big test suites that run on all production releases.
  • Does not provide complete code coverage—IAST scans only executed code to help reduce the number of false positives. It means the test does not cover all the code, including any code that was accidentally released without going through a quality assurance check.

How to Choose IAST Software

Evaluate the following criteria when selecting an IAST solution:

  • Regulations and standards—IAST solutions must be able to scan for vulnerabilities and produce reports in line with the standards and regulations your organization complies with, such as GDPR, HIPAA, PCI DSS, and SOC 2.
  • Low false positives—an IAST solution should reduce the time needed to find and eliminate false positives. It should do so without requiring reconfiguration of the tool, custom services, or ongoing tuning.
  • Automated vulnerabilities identification—an IAST solution should accurately detect known vulnerabilities while your team performs functional tests. High severity bugs should create a ticket in your bug tracking system or break the build, while sending alerts to your developers.
  • Microservices support—microservices are a mainstream method for application development, and they introduce additional attack vectors. An IAST solution should allow you to assess multiple microservices from a single interface. Learn more in our guide to microservices security.
  • Ease DevOps agile workflows deployment—IAST tools must integrate into the existing DevOps pipeline and work seamlessly with standard build and testing tools.

Sensitive data tracking—IAST should help protect personally identifiable information (PII) and company IP. You should be able to automatically track sensitive information in your applications.

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