Understanding DAST, SAST, IAST, and RASP

Static Application Security Testing (SAST) focuses on analyzing the application’s source code, bytecode, or binaries before the software is run. Because it examines the internal structure of the application, SAST is often referred to as “white-box” testing. It enables developers to identify vulnerabilities early in the development process, such as input validation flaws, insecure API usage, and misconfigurations that could lead to security weaknesses.

SAST fits into the Build stage of the DevSecOps lifecycle, making it an essential part of early-stage security efforts. One of the main strengths of SAST is its ability to catch issues before the application is even compiled or deployed, allowing teams to remediate problems when they are faster, cheaper, and less disruptive to fix. However, SAST can also produce a high volume of findings, requiring careful prioritization to avoid overwhelming developers with low-risk alerts. When integrated properly into a DevSecOps workflow, SAST acts as a critical first line of defense, helping organizations enforce secure coding practices from the very beginning of the SDLC.

Dynamic Application Security Testing (DAST) analyzes an application from the outside while it is running, without access to its internal code or structure. Often referred to as “black-box” testing, DAST simulates real-world attacks by sending various inputs to the application and observing its behavior to identify vulnerabilities like SQL injection, cross-site scripting (XSS), and authentication weaknesses.

DAST fits into the Test and Release stages of the DevSecOps lifecycle, where applications are run in staging or QA environments. DAST is particularly valuable for catching issues that only appear during runtime, such as misconfigurations, broken access controls, or exposed APIs. Unlike SAST, which focuses on the source code, DAST evaluates how the entire application stack responds under different conditions. This makes it a critical complement to static testing, helping teams uncover vulnerabilities that might only become visible when the application is deployed and interacting with users or other systems. By incorporating DAST into later stages of the SDLC, organizations can validate the effectiveness of their security controls under real-world conditions.

Interactive Application Security Testing (IAST) combines elements of both static and dynamic testing by analyzing applications from the inside while they are running. Using agents or sensors deployed within the application’s runtime environment, IAST observes how code behaves during real-time interactions, such as automated tests or manual use, and identifies vulnerabilities with greater precision than either SAST or DAST alone.

IAST fits into the Test and Release stages of the DevSecOps lifecycle, running alongside QA and integration testing. Because IAST has access to both the application’s internal code and its external behavior, it can provide highly accurate, context-rich insights into security flaws. It reduces false positives by verifying whether a vulnerability is truly exploitable in the running application. IAST is particularly useful in modern DevSecOps pipelines, as it can continuously test applications during normal development and QA processes without requiring extensive manual configuration or dedicated testing windows. By bridging the gap between static and dynamic approaches, IAST helps security teams prioritize real risks and streamline remediation efforts.

Runtime Application Self-Protection (RASP) goes beyond traditional testing by actively defending applications while they are running. Embedded directly into the application’s runtime environment, RASP continuously monitors behavior and can detect, block, or neutralize attacks in real-time. Unlike testing tools that simply identify vulnerabilities, RASP provides a layer of live protection, enabling applications to defend themselves without relying solely on external security measures.

RASP fits into the Deploy, Operate, and Monitor stages of the DevSecOps lifecycle, where applications are live and interacting with users or systems. RASP’s greatest strength lies in its ability to prevent exploitation of both known and unknown vulnerabilities by analyzing the context of each action an application takes. It can stop attacks like SQL injection, unauthorized access attempts, and API abuse even if the underlying vulnerability has not yet been patched. When used alongside testing methods like SAST, DAST, and IAST, RASP offers an additional safety net, helping organizations minimize risk between development cycles and maintain stronger security in production environments.