Key Takeaways:
- SAST, DAST, and IAST each expose different slices of risk
- No single testing method provides complete visibility — each has blind spots
- False positives and false negatives limit the effectiveness of standalone AST tools
- Integrated MAST from Quokka improves visibility and risk reduction
Quokka’s researchers recently dug into a modified version of the Android launcher app and found it had the aApplication Security Testing (AST) plays a critical role in how organizations identify and reduce software risk. Among the most common approaches are Static Application Security Testing (SAST), Dynamic Application Security Testing (DAST), and Interactive Application Security Testing (IAST).
Each method addresses a different part of the attack surface. Each introduces its own blind spots. And none of them, in isolation, provides comprehensive visibility into application risk.
This post explains how SAST, DAST, and IAST work, what each approach is good at, and best practices for incorporating these approaches.
What is Application Security Testing (AST)?
Application Security Testing refers to the tools and techniques used to identify vulnerabilities, weaknesses, and risky behaviors in software applications before they can be exploited. AST encompasses multiple methods, including SAST, DAST, and IAST, each of which scans a different layer of the application at a different point in the software development lifecycle (SDLC).
In practice, most AST programs must contend with two persistent challenges:
- False positives: Tools report issues that pose little or no real risk, creating noise and alert fatigue.
- False negatives: Exploitable vulnerabilities are missed entirely, leaving applications exposed.
Every AST approach balances coverage, accuracy, and operational cost differently. Understanding those tradeoffs is essential when designing a security program that actually reduces risk rather than generating noise.
What is Static Application Security Testing (SAST)?
Static Application Security Testing analyzes application source code or compiled code without executing the application. Because it does not require a running environment, SAST is commonly integrated early in the SDLC — often directly into CI/CD pipelines — to catch coding flaws before they reach production.
SAST benefits
- Identifies certain classes of coding flaws early in development
- Supports secure development practices and developer education
- Operates without a running application or dedicated test environment
SAST limitations
- No visibility into runtime behavior — SAST sees code, not execution
- Without careful tuning, generates high alert volumes, contributing to alert fatigue
- Limited ability to model real execution paths or conditional logic
SAST answers the question “what does this code contain?” but not “how does it behave once deployed?” That gap is where DAST and IAST become necessary.
What is Dynamic Application Security Testing (DAST)?
Dynamic Application Security Testing evaluates applications while they are running. By interacting with live systems, DAST detects vulnerabilities that only manifest during execution, such as authentication flaws, injection vulnerabilities, and insecure data handling at runtime.
DAST benefits
- Observes real runtime behavior that static analysis cannot see
- Identifies vulnerabilities that usually emerge in a running environment
- Tests the application as an attacker would, from the outside in
DAST limitations
- Limited to code paths that are actively triggered during the test session
- Requires significant setup effort and broad test coverage to be effective
- Provides less insight into underlying logic flaws or source-level root causes
The critical limitation of DAST: if a feature or code path is not triggered during testing, DAST will not identify vulnerabilities within it. This makes coverage completeness a major risk factor.
Interactive Application Security Testing (IAST)
Interactive Application Security Testing combines aspects of static and dynamic testing. With IAST, a human is driving the testing scenarios either manually or with scripts that have been created beforehand.
IAST benefits
- Links runtime findings to specific code parts that are targeted for testing, making it faster to identify which part of the application is responsible when a test reveals an issue
- Produces more actionable, context-rich findings with lower false-positive rates
- Integrates naturally into existing QA workflows
IAST limitations
- Coverage depends on the completeness of functional test suites
- Security visibility is constrained by the scope of QA testing — untested paths remain invisible
- Results may not accurately reflect production behavior if QA environments differ
IAST reduces some blind spots left by SAST and DAST, but it inherits a fundamental dependency on how thoroughly an application is exercised during testing.
SAST vs. DAST vs. IAST
No single app security testing approach covers everything. The table below maps each method against what it tests, when in the SDLC it runs, where it excels, where it falls short, and the level of false positives it tends to generate. This provides a clear picture of the benefits and tradeoffs of each approach..
SAST, DAST, IAST compared
| Attribute | SAST | DAST | IAST |
| What it tests | Source / compiled code | Running application | App during functional tests |
| When it runs | Early SDLC / CI pipeline | Staging / pre-production | During QA testing |
| Key strength | Early flaw detection | Real runtime behavior | Code-to-runtime correlation |
| Key limitation | No runtime visibility | Misses untriggered paths | Bounded by QA scope |
| False positives | Low to Moderate without tuning | None | None |
| False negatives | Low | Moderate to High | Moderate to High |
What is Mobile App Security Testing (MAST), and why do mobile apps require a different approach?
Mobile App Security Testing (MAST) is a specialized subset of AST that addresses the unique complexity of the mobile ecosystem, including multiple OS versions, diverse device configurations, embedded SDKs, compiled binaries, and runtime obfuscation that standard web-focused tools cannot handle.
Effective MAST cannot treat SAST, DAST, and IAST as independent tools. The mobile attack surface requires correlation across multiple analysis techniques, with findings from one engine informing and improving the accuracy of the next.
How Quokka combines testing methodologies for mobile app security
Quokka delivers mobile app risk intelligence to give organizations deep, continuous visibility into the security, privacy, and compliance risks within mobile applications. Our mobile app risk intelligence leverages multiple different analysis types that work together, including SAST, DAST, IAST, and Forced-Path Execution (FPE).
What is Forced-Path Execution (FPE) app analysis?
Forced-Path Execution systematically executes every conditional branch and code path within a mobile application, including those never triggered under normal use or conventional testing. By using the control-flow map produced by SAST, FPE instruments and exercises the full application to uncover hidden vulnerabilities, logic flaws, backdoors, and malicious code that standard dynamic testing would miss.
The key strength of FPE is that coverage is not left to chance. Every control path is forced and verified, eliminating the blind spots that make conventional dynamic testing an unreliable safety net for mobile applications.
Quokka’s unique approach
Modern mobile application security requires a more integrated view of code, behavior, and execution paths. Unlike traditional MAST tools that rely on limited static or dynamic checks, Quokka’s combination of different analysis types, including SAST, DAST, IAST, and FPE, uncovers hidden risks that others miss, such as supply-chain risks and embedded malicious behavior. And unlike manual penetration testing, this deep analysis is performed in minutes instead of days.
Contact us to get a customized demo of how Quokka can reduce your mobile attack surface.
FAQs
What is the difference between SAST, DAST, and IAST?
SAST analyzes source code or compiled code without running the application. DAST tests the app while it is running from the outside, and IAST instruments the application during functional testing so it can connect code behavior with runtime behavior.
Which application security testing method finds the most runtime issues?
DAST and IAST are both useful for runtime issues, but they catch different parts of the problem. DAST sees what an attacker can trigger in a live app, while IAST adds more context because it can link findings back to code execution.
Why do SAST and DAST leave blind spots?
SAST cannot see execution, so it misses issues that only show up at runtime. DAST only sees the paths it can reach during a test session, so anything outside that coverage stays hidden.
What is MAST and why do mobile apps need it?
MAST is mobile app security testing. Mobile apps add device fragmentation, OS variation, embedded SDKs, compiled binaries, and obfuscation, so web-focused testing alone does not cover the full risk surface.
