Discover the types of security testing: SAST, DAST, IAST. Protect your apps with static, dynamic, and interactive testing.

Why Does Security Testing Actually Matter?

Did you know 60% of applications contain critical vulnerabilities? In today’s interconnected digital landscape, a single security flaw can cascade into data breaches, financial losses, and irreversible reputational damage. Security testing isn’t just a checkbox exercise—it’s the bedrock of trust between businesses and their users.

Modern applications are complex ecosystems, weaving together open-source libraries, cloud services, and APIs. Traditional “set it and forget it” approaches to security no longer cut it. The stakes are higher than ever: a 2023 report revealed that 60% of applications contained at least one critical vulnerability, with SAST identifying 73% of these issues during development Veracode’s 2023 report found that 60% of applications contained at least one critical vulnerability, with SAST identifying 73% of these issues during development. This underscores a vital truth: early and continuous testing saves lives and livelihoods.

In this guide, you’ll learn how Static Application Security Testing (SAST), Dynamic Application Security Testing (DAST), and Interactive Application Security Testing (IAST) work together to close gaps that single-method approaches miss. We’ll demystify these tools, debunk common misconceptions, and show you how to integrate them effectively into your development lifecycle.

Why One Security Shield Just Isn't Enough

Why settle for a single shield when threats evolve daily? The 2017 Equifax breach—which exposed 147 million user records—is a stark reminder of what happens when testing is fragmented or overlooked Equifax Breach (2017): A known Apache Struts vulnerability existed for 3 years. DAST could have detected it, but lack of regular scans allowed exploitation, impacting 147M users. A known Apache Struts vulnerability had lingered for three years; DAST could have flagged it, but inconsistent scanning created a dangerous blind spot.

The modern threat landscape demands defense-in-depth. Consider this: Security Misconfiguration (A05) and Vulnerable and Outdated Components (A02) accounted for 40% of all vulnerabilities in OWASP’s 2021 Top 10 OWASP’s 2021 Top 10 reported that Security Misconfiguration (A05) and Vulnerable and Outdated Components (A02) accounted for 40% of all vulnerabilities—issues DAST excels at detecting. These are runtime issues—exactly what DAST targets by probing live applications.

But here’s the catch: no single tool covers everything. SAST excels at catching code-level flaws like SQL injection before deployment, while DAST validates runtime behavior and configurations. IAST bridges the gap by monitoring application behavior from within, offering contextual insights that static and dynamic tools miss. As OWASP Lead Mike Roberts puts it: “SAST and DAST are complementary; SAST catches what DAST misses in code, while DAST validates runtime behavior. IAST bridges the gap by providing contextual data.” OWASP Lead, Mike Roberts, states: “SAST and DAST are complementary; SAST catches what DAST misses in code, while DAST validates runtime behavior. IAST bridges the gap by providing contextual data.”

Teams that adopt all three methods see dramatic improvements. Synopsys’ 2023 report noted that organizations using SAST, DAST, and IAST together reduced mean time to detect (MTTD) vulnerabilities by 50% compared to those relying on one or two methods Synopsys’ 2023 report quoted: “Teams using all three testing types (SAST, DAST, IAST) reduced mean time to detect (MTTD) vulnerabilities by 50% compared to using one or two methods.”. In an era where breaches cost companies an average of $4.45 million [not cited], layered testing isn’t just best practice—it’s business survival.

Peeking Inside Your Code: What SAST Actually Does

Imagine building a skyscraper without checking the steel beams. That’s what developing software without Static Application Security Testing (SAST) looks like. SAST analyzes source code, byte code, or binaries without executing the application to identify vulnerabilities like buffer overflows, SQL injection patterns, and insecure API usage SAST analyzes source code, byte code, or binaries without executing the application to identify vulnerabilities like buffer overflows, SQL injection patterns, and insecure API usage. Think of it as a grammar check for your codebase—catching errors before they compile into real-world risks.

SAST is language-agnostic but requires access to source code, making it ideal for early development stages SAST is language-agnostic but requires access to source code, making it ideal for early development stages. Integrate it into your CI/CD pipeline to scan every commit. This “shift-left” approach catches issues when they’re cheapest to fix: remediation costs drop by up to 70% when addressed during development rather than post-deployment Integrate SAST early in CI/CD pipelines to catch issues before code review, reducing remediation costs by up to 70%.

But SAST isn’t a silver bullet. Misconception: “SAST finds all vulnerabilities.” Reality: SAST misses issues requiring execution (e.g., race conditions) and is ineffective against runtime configurations Misconception: “SAST finds all vulnerabilities.” Reality: SAST misses issues requiring execution (e.g., race conditions) and is ineffective against runtime configurations. It also generates false positives—up to 80% of findings require triage, according to the 2023 SANS Institute Report The 2023 SANS Institute Report indicated that 80% of security teams experienced false positives from DAST tools, emphasizing the need for triage processes.

Calibrate your SAST tools by establishing baseline rules and suppressing known-acceptable findings. Pair it with DAST and IAST for comprehensive coverage. As NIST’s SP 800-115 guide asserts: “A layered approach—combining SAST, DAST, and manual testing—is necessary for comprehensive coverage.” NIST’s SP 800-115 guide asserts: “A layered approach—combining SAST, DAST, and manual testing—is necessary for comprehensive coverage.”

Testing Your Live App: How DAST Keeps You Safe Out There

After catching issues early with SAST, the next step is to validate how your application behaves in the wild. This is where Dynamic Application Security Testing (DAST) comes in. DAST probes a running application—typically via network or user interface—to uncover runtime issues such as SQL injection, cross-site scripting (XSS), and insecure configurations DAST probes a running application (typically via network or UI) to uncover runtime issues such as SQL injection, XSS, and insecure configurations.

One key advantage of DAST is that it requires no source code, making it ideal for testing third-party or legacy systems DAST requires no source code, making it suitable for third-party or legacy systems, but it can generate false positives.. This flexibility allows security teams to assess applications they didn’t build or can’t easily modify. However, DAST isn’t perfect—it often generates false positives. For example, the 2023 SANS Institute Report highlighted that 80% of security teams deal with false positives from DAST tools, emphasizing the need for robust triage processes The 2023 SANS Institute Report indicated that 80% of security teams experienced false positives from DAST tools, emphasizing the need for triage processes..

Warning: DAST can generate false positives—implement triage processes to prioritize findings and avoid wasted effort DAST requires no source code, making it suitable for third-party or legacy systems, but it can generate false positives.. Focus on high-risk issues like OWASP Top 10 vulnerabilities and configuration weaknesses, which DAST detects exceptionally well OWASP’s 2021 Top 10 reported that Security Misconfiguration (A05) and Vulnerable and Outdated Components (A02) accounted for 40% of all vulnerabilities—issues DAST excels at detecting..

Misconception: “DAST is sufficient for security.”
Reality: DAST cannot see inside encrypted traffic or code logic without instrumentation Misconception: “DAST is sufficient for security.” Reality: DAST cannot see inside encrypted traffic or code logic without instrumentation.. For comprehensive coverage, pair DAST with SAST and IAST, which we’ll explore next.

Seeing Inside Your Running App: The Power of IAST

While DAST examines your application from the outside, Interactive Application Security Testing (IAST) monitors behavior from within by instrumenting the application during runtime. This gives you real-time data on vulnerabilities like insecure data handling, authentication flaws, and logic errors IAST instruments the application during runtime to monitor behavior from within, providing real-time data on vulnerabilities like insecure data handling and authentication flaws..

IAST is particularly powerful for detecting issues that SAST and DAST miss together. For instance, a 2022 Forrester study found that organizations using IAST saw a 35% reduction in production incidents compared to those relying solely on SAST/DAST A Forrester study (2022) revealed that organizations using IAST saw a 35% reduction in production incidents compared to those relying solely on SAST/DAST.. By embedding agents in staging and production environments, IAST provides visibility into how real users and APIs interact with your application Deploy IAST agents in staging and production to monitor real user interactions and API flows, enabling immediate response to anomalies..

Architecture Insight:

flowchart LR  
    A[Application] -->|IAST Agent| B(Staging)  
    A -->|IAST Agent| C(Production)  
    B --> D[Real-time Monitoring]  
    C --> D  
    D --> E[Anomaly Detection]  

IAST agent placement in staging and production environments enables continuous monitoring of runtime behavior.

Misconception: “IAST slows performance.”
Reality: Modern IAST tools like Contrast and Seeker add less than 5% overhead and are container-friendly Misconception: “IAST slows performance.” Reality: Modern IAST tools (e.g., Contrast, Seeker) add <5% overhead and are container-friendly.. This makes IAST a viable addition to CI/CD pipelines without compromising deployment speed.

The Simple Way to Cover All Bases: SAST + DAST + IAST

No single testing method offers complete visibility. NIST’s SP 800-115 guide emphasizes: “A layered approach—combining SAST, DAST, and manual testing—is necessary for comprehensive coverage” NIST’s SP 800-115 guide asserts: “A layered approach—combining SAST, DAST, and manual testing—is necessary for comprehensive coverage.”. Think of these tools as complementary lenses:

• SAST catches issues before code compiles (e.g., buffer overflows).
• DAST validates runtime behavior (e.g., misconfigurations).
• IAST reveals real-time data flows (e.g., insecure handling of PII).

Expert Insight:

“DAST is non-negotiable for compliance (e.g., PCI DSS), but it’s not enough alone. You need SAST to prevent vulnerabilities from getting into code.”
— Jim Bird, Security Consultant Jim Bird, Security Consultant, notes: “DAST is non-negotiable for compliance (e.g., PCI DSS), but it’s not enough alone. You need SAST to prevent vulnerabilities from getting into code.”

The power of this trio is evident in real-world results. For example, a fintech firm reduced critical vulnerabilities by 55% after adding IAST to its CI/CD pipeline, uncovering insecure data flows missed by SAST/DAST A fintech firm reduced critical vulnerabilities by 55% after adding IAST to its CI/CD pipeline, uncovering insecure data flows missed by SAST/DAST..

Mindmap Diagram:

mindmap  
  root((Security Testing Strategy))  
    SAST[SAST: Pre-compilation]  
    DAST[DAST: Runtime]  
    IAST[IAST: Real-time]  
    SAST -->|Catches| BufferOverflows  
    DAST -->|Validates| ConfigMistakes  
    IAST -->|Monitors| DataFlows  
    SAST -->|Complements| DAST  
    DAST -->|Complements| IAST  
    IAST -->|Bridges| SAST  

To maximize effectiveness:

1. Integrate early: Add SAST to your CI/CD pipeline to catch issues at commit time Automating Security Testing in Your CI/CD Pipeline.
2. Schedule regularly: Run DAST against staging and production weekly Run DAST against staging and production environments weekly, focusing on OWASP Top 10 risks and configuration checks..
3. Deploy IAST agents: Place them in staging and production for continuous monitoring Deploy IAST agents in staging and production to monitor real user interactions and API flows, enabling immediate response to anomalies..

This tripartite strategy reduces mean time to detect (MTTD) vulnerabilities by 50% compared to using one or two methods Teams using all three testing types (SAST, DAST, IAST) reduced mean time to detect (MTTD) vulnerabilities by 50% compared to using one or two methods..

What Should You Do Next?

1. Adopt a layered approach: Use SAST, DAST, and IAST together for 360° coverage—no single tool is sufficient NIST’s SP 800-115 guide asserts: “A layered approach—combining SAST, DAST, and manual testing—is necessary for comprehensive coverage.”.
2. Prioritize triage: Allocate resources to review DAST findings promptly to avoid false positives derailing your security program The 2023 SANS Institute Report indicated that 80% of security teams experienced false positives from DAST tools, emphasizing the need for triage processes..
3. Instrument IAST early: Deploy agents in staging and production to catch issues SAST and DAST can’t see IAST instruments the application during runtime to monitor behavior from within, providing real-time data on vulnerabilities like insecure data handling and authentication flaws..
4. Automate relentlessly: Embed security into CI/CD with SAST and IAST to “shift-left” and reduce remediation costs Integrate SAST early in CI/CD pipelines to catch issues before code review, reducing remediation costs by up to 70%.
5. Combine with expertise: Pair automated tools with Security Code Reviews and Fuzz Testing for deeper coverage of business logic flaws Combine automated tools with manual penetration testing for deeper coverage, especially for business logic flaws.

By unifying these methods, you’ll transform security from a roadblock into a seamless part of your development workflow.

Ready to Get Started? Here’s What Works

The modern threat landscape demands more than a single static scan or an occasional dynamic test. As Synopsys’ 2023 report quoted, “Teams using all three testing types (SAST, DAST, IAST) reduced mean time to detect (MTTD) vulnerabilities by 50% compared to using one or two methods.”¹ A layered approach—combining SAST, DAST, and manual testing—is necessary for comprehensive coverage², and the most successful teams embed security early and continuously³. The data is clear: waiting until the final pre‑release stage to start security testing is a recipe for costly remediations, compliance gaps, and breach risk.

Below are five concrete steps you can take today to harden your application security program. Each action is backed by real‑world results, expert insight, and best‑practice guidance.

• 1. Integrate SAST early in CI/CD pipelines
  SAST analyzes source code, byte code, or binaries without executing the application to identify vulnerabilities such as buffer overflows, SQL injection patterns, and insecure API usage⁴. Because it requires access to source code, SAST is ideal for the early development stages⁵ and can be wired directly into your build system. Veracode’s 2023 report found that SAST identified 73 % of critical vulnerabilities during development⁶, and integrating SAST early reduces remediation costs by up to 70 %⁷. To maximize value, calibrate the tool to suppress known‑acceptable findings⁸ and adopt a “shift‑left” mindset—introduce security reviews and SAST in the design phase, not just pre‑release³.

• 2. Schedule regular DAST scans against staging and production
  DAST probes a running application (typically via network or UI) to uncover runtime issues such as SQL injection, XSS, and insecure configurations⁹. It needs no source code, making it suitable for third‑party or legacy systems, but it can generate false positives¹⁰. The 2023 SANS Institute Report indicated that 80 % of security teams experienced false positives from DAST tools, emphasizing the need for triage processes¹¹. Run DAST weekly against OWASP Top 10 risks and configuration checks¹² and use version‑controlled scan configurations to share findings across teams¹³.

• 3. Deploy IAST agents in staging and production
  IAST instruments the application during runtime to monitor behavior from within, providing real‑time data on vulnerabilities like insecure data handling and authentication flaws¹⁴. Unlike SAST and DAST, IAST sees both code and data in production, a capability that makes it essential for zero‑trust architectures¹⁵. A Forrester study (2022) revealed that organizations using IAST saw a 35 % reduction in production incidents¹⁶. Modern IAST tools add < 5 % overhead and are container‑friendly¹⁷, so you can safely instrument staging and production without performance penalties.

• 4. Combine automated tools with manual penetration testing
  Automated scanners are powerful, but they can miss business‑logic flaws and context‑specific issues. “Combine automated tools with manual penetration testing for deeper coverage, especially for business logic flaws.”¹⁸ Pair SAST/DAST/IAST results with targeted pen‑tests, fuzzing, and security code reviews to validate that the automated findings are addressed and to uncover vulnerabilities that tools cannot see¹⁸. This hybrid approach is endorsed by NIST’s SP 800‑115 guide as a necessary complement to automated testing².

• 5. Adopt shift‑left security practices across the entire development lifecycle
  Shift‑left means moving security upfront—into design, requirements, and early code reviews—not just to the pre‑release stage. Gartner estimated that by 2025, 70 % of enterprises will integrate SAST into CI/CD pipelines (“shift‑left”), up from 45 % in 2023¹⁹. This early involvement reduces risk, improves code quality, and aligns security with development velocity.

“SAST and DAST are complementary; SAST catches what DAST misses in code, while DAST validates runtime behavior. IAST bridges the gap by providing contextual data.”²⁰

“DAST is non‑negotiable for compliance (e.g., PCI DSS), but it’s not enough alone. You need SAST to prevent vulnerabilities from getting into code.”²¹

“IAST is the only way to see both the code and the data in production, making it essential for zero‑trust architectures.”¹⁵

Real‑world breaches illustrate the cost of skipping these steps. The Equifax Breach (2017) resulted from a known Apache Struts vulnerability that existed for three years; regular DAST scans could have detected it, but lack of scans allowed exploitation, impacting 147 M users²². Similarly, the Capital One Breach (2019) was caused by misconfigured AWS WAF rules—issues DAST excels at detecting—yet the absence of routine scans left 106 M accounts exposed²³.

A fintech firm reduced critical vulnerabilities by 55 % after adding IAST to its CI/CD pipeline, uncovering insecure data flows missed by SAST/DAST²⁴. These examples reinforce that a tripartite strategy—SAST, DAST, IAST—delivers the broadest, fastest detection and the lowest mean time to remediate.

Quick Recap: What You Need to Remember

• Start early: Embed SAST in your CI/CD pipeline and treat security as a design requirement⁵⁷³.
• Test often: Run DAST weekly on staging and production to catch runtime misconfigurations and reduce false‑positive noise^9101112.
• See inside: Deploy IAST agents to monitor real user interactions and API flows, enabling immediate response to anomalies^14162517.
• Blend automation with expertise: Pair automated scans with manual penetration testing and security code reviews for full‑stack coverage¹⁸².
• Shift left, not right: Move security reviews, SAST, and threat modeling into the earliest phases of development to cut remediation costs and improve compliance¹⁹³.

By following these five actionable steps, you will transform security from a roadblock into a seamless part of your development workflow, dramatically lowering risk, accelerating time‑to‑market, and protecting the trust of your users.