SAST, DAST, and Everything in Between: Making Sense of AppSec Technologies

Why Application Security Testing Matters

Applications today sit at the heart of business operations — which makes their security and reliability business-critical issues. They handle sensitive data, transactions, and daily operations, which also makes them a top target for attackers. In 2025, web application and API attacks surged to over 311 billion incidents, and nearly 6 out of 10 of these data breaches were caused by flaws in the application on a non-infrastructural level.

Hackers actively exploit misconfigurations, weak encryption, and coding flaws such as SQL Injection or XSS. When attacks succeed, the impact extends beyond data theft — leading to high costs of downtime, regulatory exposure, and erosion of customer trust.

Application Security Testing breaks this cycle by shifting defense earlier in the lifecycle. It uncovers vulnerabilities before they can be weaponized, reducing breach costs, preventing downtime, and protecting the trust and safety of customers — all while keeping business running without interruption.

Understanding the Basics of AppSec Technologies

Application security (or AppSec) — is the way of safeguarding software against exploitable and non-exploitable vulnerabilities. It emerged when organizations realized that firewalls and network defenses alone could not stop threats embedded in the code itself. Attacks such as SQL Injections and Cross-Site Scripting underscored the need for dedicated testing tools to identify weaknesses before they hit the production.

Modern applications are built on open-source components, third-party APIs, and cloud platforms, dramatically expanding the attack surface. To manage this complexity, development teams have embraced DevSecOps and integrated secure coding practices that check for risks at every stage of the lifecycle — reducing exposure, cutting remediation costs, and preserving user trust.

The main AppSec technologies include 

• Static Application Security Testing (SAST)
• Dynamic Application Security Testing (DAST)
• Interactive Application Security Testing (IAST)
• Runtime Application Self-Protection (RASP)
• Software Composition Analysis (SCA) tools

These approaches cover code analysis and active runtime protection. Together, they form what AppSec looks like.

What is SAST? (Static Application Security Testing)

Static Application Security Testing is a white-box testing approach that scans source code, bytecode, or binaries without actually running the app. It works by using data flow analysis or control flow analysis (and many more) techniques to detect security issues like: 

• SQL injection
• cross-site scripting
• insecure deserialization
• buffer overflows
• hardcoded credentials or API keys
• missing or improper authentication checks
• insecure role-based access enforcement (authorization bypass)
• insecure default configurations
• disabled or missing security checks (e.g., SSL certificate validation bypass)
• use of dangerous functions/APIs (strcpy, eval, exec)
• etc

SAST has become important in the secure software development lifecycle. When developers add it to CI/CD pipelines, the technology helps DevSecOps practices by giving quick feedback that shows up right in IDEs or version control systems. Problems get marked at exact code lines, with background info and fix tips.

Developers usually run a SAST tool while they're coding or during commits. The software finds bad code patterns, explains the security risk, and gives safer coding options that help make the application stronger before it goes live.

What is DAST? (Dynamic Application Security Testing)

Dynamic Application Security Testing (DAST) works as a black-box testing approach that checks an application while it's actually running. Different from Static Application Security Testing, DAST doesn't need the source code at all. Instead, it tests the app "from the outside in" by acting like a real attacker trying to break into the system.

DAST catches problems that only show up when the app is live. These include: 

• Misconfigured servers
• Authentication issues
• Denial-of-Service attacks

By watching how an application reacts to fake attacks, DAST helps dev teams build better defenses for the real world.