Dynamic Application Security Testing (DAST) – All Questions Answered

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Dynamic Application Security Testing (DAST in short) is becoming an integral part of the software development life cycle. This application security scanner aims not to replace application penetration testing but to enhance the security and compliance development process.

Introduction to AppSec Mechanisms

Application vulnerabilities are a major cause of cyberattacks, with 84% of security incidents in 2019 happening at the application layer. To help with this, Application Security (AppSec) outlines a collection of processes and tools focused on identifying, remediating, and preventing application-level vulnerabilities during various phases of application development.

As modern application development leverages a continuous deployment and integration (CI/CD) approach for faster delivery, the approach to application security testing requires to be automated and administered throughout the software’s life cycle. As a result, a comprehensive AppSec involves several mechanisms, including:

Dynamic Application Security Testing (DAST) involves scanning an application for vulnerabilities and simulating an attack while the code runs. Security teams use DAST tools and techniques to identify runtime vulnerabilities such as server misconfiguration, weak authentication, and other problems likely to be encountered once a user is logged in. This post is a comprehensive guide to Dynamic Application Security Testing and how it differs from other AppSec testing mechanisms.

DAST - Dynamic Application Security Testing in a graph

What is Dynamic Application Security Testing (DAST)?

DAST tools typically have no access to application source code and are primarily used to simulate external attacks. DAST tests are written by ethical hackers to attack the application externally by checking for critical flaws and potential security vulnerabilities on exposed attack surfaces. These experts then gather information on the application’s security vulnerability depending on how it responds to these simulations.

While DAST is performed on running code, it doesn’t have to be necessarily done on production instances. These tests are often performed by QA analysts in simulated test environments to gather insights without performing simulated attacks on the running application on production.

DAST is categorized as a Black Box Security Testing approach to uncover potential security issues.  DAST has a better false-positive rate than other application security testing tools.

Why do firms need DAST?

DAST helps organizations identify key runtime and exploitable web application vulnerabilities missed during code development and verification. Such tools also demonstrate the application’s response to an attack, which is what most external attackers exploit to gain more control.  

A DAST mechanism offers several benefits to organizations, including:

  • Continuously identify new attack vectors that can compromise system security
  • Optimum approach for testing API security
  • Detect security governance and compliance requirements that may also include self-reported runtime vulnerabilities
  • Obtain insights into application performance and resource consumption
  • Lower false positives


Dynamic and Static Application Security Testing (SAST) are two AppSec technologies that utilize unique approaches to identify weaknesses and potential vulnerabilities. Some differences between the two testing mechanisms include the following:

  1. SAST uses a white-box approach by leveraging the elemental source code and performing internal scans while the code remains static. On the other hand, DAST uses a black-box testing approach, where the tester discovers an application’s vulnerabilities from an external ecosystem during application runtime.
  2. SAST tests for application/source-code vulnerabilities, while DAST tests for runtime and environment issues.
  3. DAST evaluates security risks in web apps, databases, servers, and services, while SAST primarily assesses the application architecture and design environment, mobile applications, and real-time systems.

DAST Pros and Cons

DAST tools are widely adopted to scan web applications for exploitable vulnerabilities due to several advantages this offer, including:

  • They are platform-independent and can be used to test applications independent of their hardware, design, internal architecture, or programming language
  • Efficiently pinpoint configuration issues at runtime
  • Can also identify memory consumption and resource usage
  • By simulating the movements of threat actors, DAST helps identify issues that may have been missed by development teams in earlier stages
  • Efficiently scan for Web API threats

While the advantages far outweigh the limitations, the following are some of the commonly known challenges of using a DAST mechanism:

  • DAST scanning offer limited scalability to simulate attacks at a larger scale
  • Lacks visibility into an application’s codebase

Introducing DAST to an SDLC

DAST combines vulnerability scanning with penetration testing to assess an application’s security posture in a running state. To do so, DAST tools typically inject faulty code and configurations into the application to detect and identify known security vulnerabilities.

The following section explores how organizations can include a DAST scanner into the right stages of a Software Development Lifecycle to ensure that real vulnerabilities are identified earlier than they get exploited without employing the very pricy manual penetration testing approach.

How DAST Enhances Web Application Security

A common approach to DAST testing relies on a centralized registry of Common Weakness Enumeration (CWE) and Common Vulnerabilities and Exposures (CVE) to cross-reference and validate the severity of the susceptible points. These tools typically scan the HTML and HTTP interfaces for common security vulnerabilities, then perform automatic penetration testing for any exposed surfaces. A report of these vulnerabilities helps teams to update the application with patches for the vulnerabilities identified, improving application security.

When to Integrate DAST for AppSec

Successive DAST requires a security team with extensive knowledge of web servers, traffic flow, and common vulnerabilities to write tests and refine the testing approaches. Since DAST examines dynamic runtime environments, it is usually sensible to introduce the approach once the code has been developed and verified. DAST tools are commonly deployed when the application is going into production, identifying weaknesses that threat actors can exploit and then illustrating how these flaws can be used for unauthorized access. 

Vulnerabilities Exposed by DAST

DAST explores various attack scenarios and techniques attackers use to access web applications. Vulnerabilities and attacks uncovered by DAST include:

Cross-Site Scripting (XSS) – A client-side vulnerability that lets the attacker include malicious code on a legitimate web page to execute malicious actions on a victim’s web browser.

Injection Errors – Malicious actors, disguised as users, use injection flaws to send untrusted data to web servers as part of a command. Injection attacks are often aimed at various targets such as:

Server Misconfiguration – In these attacks, the threat actor attempts to exploit weaknesses in the configuration of web server components. 

DAST Solutions and Tools

Several existing DAST platforms make it easy for any organization to start dynamic application testing. This section explores the factors to consider when selecting a DAST platform and some popular DAST solutions.

Selecting a DAST Platform

DAST solutions vary in scope and capabilities, resulting in varying flavors and pricing options. Here are a few factors security teams should consider when looking for a DAST platform:

Scan Frequency

DAST tools offer various options when it comes to the scanning frequency and duration:

  1. CI/CD Automated Scans – Integrates security testing into the DevOps pipeline leading to quicker detection and remediation
  2. Scheduled Scans – Automated scans between set intervals
  3. Manual Scanning – Scanning is initiated by a member of the team at scheduled times

Application Target

While DAST performs scans on running workloads, the tool can be used to target applications both in production and pre-production (test) environments. 

End Users

DAST is refined depending on whose responsibility it is to scan for weaknesses. They could be built for security analysts, engineering teams, or both.

API Security

DAST platforms that support API security testing are suitable for modern applications since APIs are increasingly becoming a threat vector.

Deployment Model

DAST solutions can be deployed on-premises or as SaaS options in the cloud, with different benefits for different use cases.

Single Page Application Security Testing

Single-page applications require a DAST that interfaces with a static Document Object Model (DOM) to identify the various paths on which the tests are run.

Some of the popular DAST solutions include:

Crashtest Security Suite

Crashtest is an end-to-end vulnerability DAST tool that helps DevOps teams and organizations establish a continuous testing process to reduce the chances of application attacks through API or Web Application attack surfaces. The scanner also offers a reduced false positives rate to help you plan, scan, and remediate faster. One can start for free right away and then pick the subscription plan that suits them best.


Acunetix is a DAST tool that includes a dashboard with a suite of tools that scan web services and websites for vulnerabilities on demand. Acunetix requires on-site installation of downloaded software and comes in three pricing options for different tiers of support.

Veracode Dynamic Analysis

This straightforward DAST service easily integrates into the CI/CD toolchain to develop secure applications and websites. It has a high-powered vulnerability scanner that allows testers to bypass login screens on allowed web systems.


A flexible security platform enables on-demand checks and penetration tests by system administrators. AppCheck performs scans and pen tests through a browser, allowing for the probing of all access points for system weaknesses.


This automatic security solution combines DAST and SAST functionalities for interactive application testing. Checkmarx dynamic processes check running applications for OWASP top 10 vulnerabilities and send fault reports to the DevOps workflow.

DAST Explained in a Video

DAST Frequently Asked Questions Explained In A Video


DAST is fast becoming an increasingly important factor in AppSec, with about 35% of investment in web and application security estimated to be spent on dynamic runtime scanners. These tools enable organizations and security teams to improve application security by simulating and remediating runtime attacks before they occur. Modern security teams combine DAST and SAST tools for interactive and continuous testing, which aligns with the goals of DevOps and modern CI/CD pipelines.

Crashtest Security offers a comprehensive security assessment to ensure that every transaction on your web application is sufficiently logged with integrity controls. To know more about how Crashtest Security can perform a comprehensive scan and protect your tech stack from malicious attacks, just test our DAST scanner for free here.

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