.png)
.png)
.png)
.png)
Security Toolchain: Dynamic Application Security Testing (DAST)
What is DAST?
Dynamic Application Security Testing (DAST) is a black-box security testing method for running applications. DAST conducts comprehensive security assessments by simulating hacker attacks, analyzing the application's response behavior in real time to identify potential vulnerabilities. As technology advances, the capabilities of modern DAST tools are also expanding to include host assessment and configuration scanning.
Core Capabilities of DAST
1. Vulnerability Detected
DAST effectively detects vulnerabilities listed in the OWASP Top 10 (such as SQL Injection, XSS, SSRF, etc.) as well as publicly available vulnerability database such as CVE, CNVD, and CNNVD.
2. Black Box Testing Feature
DAST conducts in-depth scanning of runtime applications, API, and Internet of Things (IoT) devices by simulating the behavior of real attackers. It is therefore capable of identifying numerous security risks, including authentication bypass, sensitive data leakage, and business logic bugs. It also supports the detection of known vulnerabilities in common middleware and third-party components.
3. Attack Depth Simulation
DAST reproduces key segments of hacker attack chains through intelligent form filling, multi-dimensional parameter tampering (including HTTP headers, URL params, and request body), in addition to malicious payload injection.
DAST’s Working Principle
The working principle of DAST active scanning involves three stages, which aim to simulate the behavior of attackers to recognize potential risks.
1. Information Gathering (Structural Discovery)
DAST tools conduct automated crawling to comprehensively scan the application, covering all accessible directories, pages, and parameters. The crawler simulates user interaction behaviors (such as tapping links and submitting forms) to recognize the URL structure, input parameters (such as form fields and query strings), and interaction points.
The purpose of this phase is to construct a complete logical map of the application, including AJAX pages, API, and other dynamic elements, ensuring that testing covers as many entry points as possible.
2. Attack Attempt (Vulnerability Scanning)
Based on the results of phase one, DAST tools dynamically construct malicious requests using a built-in database and sends them to the target application for security assessment. The attack process is automated, conducting multi-dimensional testing on each discovered page and parameter to ensure the simulation of real threat scenarios.
3. Response Analysis (Vulnerability Verification)
DAST tools monitor the application's responses in real-time, including status code, response body, and error messages. By analyzing the response data (such as exception error output, delayed responses, or data leakage), DAST can determine whether there are exploitable security vulnerabilities. It then shares a detailed report identifying existing vulnerabilities, d, sharing their location of (such as specific URLs and parameters) and an assessment of threat level.
Figure 1: DAST Active Scanning Implementation Principle Schematic Diagram
DAST passive scanning employs a non-intrusive approach, monitoring network traffic during the
application's operation (including request/response, cookies, DOM, etc.) and
analyzing data flow without sending any test attack vectors, to ensure that the
testing process does not affect the normal operation of the system. This
mechanism captures traffic through devices or software deployed at critical
network nodes (such as gateway or mirroring port), or combines with system logs
(such as server access records), to provide an in-depth analysis.
DAST passive monitoring is therefore capable of detecting various runtime
vulnerabilities, such as Cross-Site Scripting (XSS), SQL Injection, sensitive
information leakage, and logic errors (e.g., access control bugs). It can also
identify abnormal behavior (such as brute-force access attempts). This method,
based on real user interaction, provides crucial insights for the active
scanning stage, enhancing the coverage and accuracy of vulnerability
recognition.
Figure 2: DAST Passive Scanning Implementation Principle Schematic Diagram
Advantages and Limitations of DAST
Figure 3: Comparison of Advantages and Limitations of DAST
Advantages:
1. No code dependency: DAST does not need to access an application’s source code, nor does not it rely on an application's development language, frame, or technology. This means DAST can assess the overall security of various applications, services, and APIs.
2. Detecting runtime vulnerabilities: By simulating attacker behavior, DAST can recognize exploitable security vulnerabilities (such as SQL Injection, XSS), configuration errors, invalid security headers, and other issues that are only exposed in the runtime state.
3. Highly efficient recognition of known vulnerabilities: Based on publicly available vulnerability databases,, DAST provides automated detection of publicly known vulnerabilities, such as the OWASP Top 10..
Limitations:
1. Limited testing depth: DAST’s black box testing feature results means it cannot cover deep business logic and unexecuted code paths.
2. Slow scanning speed: DAST must simulate a large number of request tests with different Inputs, meaning complex applications may require several hours to complete a scan.
3. Vulnerability localization is vague: DAST cannot precisely locate the exact source code lines associated with a vulnerability, which requires manual analysis.
The Future of DAST
As AI technologies develop rapidly, DAST is also developing intelligent and automated threat-detection capabilities. In the future, AI will transform dynamic application security testing in three main ways:
1. Agentic AI-led Decision-Making and Execution
Based on the autonomous decision-making capabilities of large models, DAST tools will shift from passive response to active prediction. Through supervised learning and multi-step reasoning techniques, DAST will be able to autonomously generate dynamic testing strategies and optimize attack vector injection paths in real time. For example, the system will be able to understand the hacker's thought process, adjusting scanning depth to the business context to enhance the efficiency of discovering 0-day vulnerabilities.
2. Multimodal Collaboration and Scene Generalization
DAST will be able to integrate data systems such as network traffic analysis, code behavior monitoring, and configuration state awareness to construct a "dynamic application risk graph." This will not only provide a far more complex vulnerability assessment, but also enable the prediction of vulnerability combination attack chains. Furthermore, synthetic data technology will significantly reduce the reliance on real production environments, allowing the pre-emptive simulation of complex attack scenarios within virtual environments.
3. Secure Operation Closed Loop and Defense Coordination
AI-driven automation is no longer limited to the detection phase. The new generation of DAST will link with RASP (Runtime Application Self-Protection), WAF, and other defense systems to form an autonomous loop of "Detection-Response-Reinforcement". For example, after discovering a vulnerability DAST will automatically generate a virtual patch and then verify its effectiveness. Through real-time interaction with the threat intelligence platform, DAST will dynamically update the rule database to achieve immediate immunity against new types of attacks.
Next Issue Preview
In this article, we explored the concept, capabilities, principles, and limitations of Dynamic Application Security Testing (DAST). We observed that DAST acts like an external attacker, launching various tests on running applications to help identify potential vulnerabilities that could be exploited by attackers.
In the next article, we will focus on the emerging technology in application security testing: Interactive Application Security Testing (IAST). If DAST is an "external attacker," then IAST is a "crime scene investigator" equipped with advanced instruments that provide a deep analysis of vulnerabilities. IAST is deployed within the application's runtime environment, enabling real-time monitoring of requests, responses, and the application’s internal data flow during execution. This allows IAST to accurately pinpoint the code location corresponding to vulnerabilities and further enhance the depth of security testing.
Stay tuned as we discuss the mysteries of IAST together!
Disclaimer:
The analysis and discussion in the article aim to share industry trends and technical practices. If there are any issues related to intellectual property, please feel free to contact us, and we will handle and adjust accordingly in accordance with relevant laws and regulations.
