7 Battle-Tested Tips for Using a DAST Scanner

While modern web applications are growing in complexity, the threat landscape is also constantly evolving. It can be difficult for developers to identify and remediate vulnerabilities in their code, especially if they need more expertise in security. As a result, manual application security testing has become ever more challenging and intricate.

Dynamic Application Security Testing (DAST) tools address these challenges by automatically identifying vulnerabilities in web applications. DAST tools work by simulating real-world attacks on the application, such as SQL injection and cross-site scripting (XSS), and reporting all vulnerabilities discovered in the process–saving you time and effort while identifying vulnerabilities that may be difficult to find manually.

With that in mind, this article explores what DAST tools are and provides seven tips for integrating them into your development process.

How DAST tools work

Several types of DAST software are available to help you find and fix vulnerabilities in your web applications before attackers can exploit them. These include:

• Web Application Scanners: These tools automatically scan your web application for vulnerabilities such as SQL injection, cross-site scripting, and other common attack vectors.
• Web Application Firewalls (WAFs): These tools act as a barrier between your web application and the internet, protecting it from unauthorized access and malicious traffic.
• Interactive Application Security Testing (IAST): These tools combine dynamic testing with static analysis to identify real-time vulnerabilities while the application is running.

Penetration Testing: This test simulates a real-world attack on your web application, identifying vulnerabilities that an attacker can exploit.

How DAST tools differ from others

Since DAST adds extra runtime insights to the static source-code analysis, it works well with application security testing techniques that rely on static checks, such as SAST and SCA. However, since a DAST tool only analyses specific use cases rather than theoretical inputs, certain sections of your code that fail in edge circumstances may be overlooked. Tools such as SAST, IAST, and SCA are helpful in this situation to examine the source code and identify faulty behavior that might go unnoticed by DAST.

The Pros and Cons of DAST

Pros

• Flexible and customizable: DAST scanners allow you to tailor your testing to specific needs. This is particularly useful if you use a niche programming language, as DAST tools can be adapted to work with any language.
• Provides a comprehensive assessment of your web application’s security: These tools scan your entire application looking for vulnerabilities that attackers could exploit to ensure that you’re not missing any potential gaps.
• Helps uncover vulnerabilities that are not usually found in the source code: These tools simulate real-world attacks on your application, revealing vulnerabilities that may not be visible in the source code. This can include vulnerabilities in the application’s configuration or environment, such as misconfigured servers or lack of encryption.

Cons

• Not highly scalable: Testing large and complex applications using DAST can be difficult and time-consuming, making it less suitable for organizations with many web applications to experiment with.
• Can be slow: Analyzing the application’s behavior during runtime may take significant time, which can create a bottleneck for organizations that need to test their applications quickly.
• Does not provide code visibility: DAST only analyzes the application’s behavior during runtime and does not provide insights into the application’s underlying code. This means thay identifying and fixing the root cause of security vulnerabilities using DAST alone can be challenging.

7 battle-tested tips for using a DAST scanner

1) Use DAST as early in the SDLC as possible to make fixes easier and cheaper

The earlier vulnerabilities are identified, the less expensive and time-consuming it is to fix them. By integrating DAST early into the SDLC, developers can quickly identify and fix vulnerabilities.

This practice also allows for more comprehensive testing, as the entire application can be scanned, ensuring all vulnerabilities are identified and addressed before the application is deployed. The resulting final product will be more secure for end users.

2) Integrate DAST into various points in the CI/CD to detect problems earlier in the software build

By integrating DAST into various points in the CI/CD pipeline, organizations can identify and fix security vulnerabilities early in the software development process, which can help improve the overall security of their applications and avoid delays in the deployment process.

One way to integrate DAST is to schedule DAST scans as part of the unit testing phase. This allows the development team to identify and fix potential vulnerabilities before merging the code into the main branch.

You can use DAST scans as part of the integration testing phase, allowing you to identify and fix any potential vulnerabilities that may have been introduced during integration. DAST scans can also be scheduled during the deployment phase, allowing you to identify and resolve potential vulnerabilities before the application is deployed to production, reducing the risk of a security breach.

3) Set up automation for complex interactions

Setting up automation for complex interactions using DAST requires a multi-step process:

1. Sit down with users to understand how they use the application: Only by knowing how users interact with the application can you identify the most complex interactions that need to be automated. Conducting user interviews, observe user behavior, and review user feedback.
2. Use an automation tool for scripting user’s actions: Once the complex interactions have been identified, an automation tool can be used to script the user’s actions. These scripts can then be used to simulate user behavior during DAST scans.
3. Add the test scripts to the CI/CD pipeline: The test scripts could be added to the CI/CD pipeline so that DAST scans are automatically triggered when changes are made to the application. This ensures that the application is regularly tested for security vulnerabilities.
4. Add regression tests to the testing suite to ensure that the complex interactions continue to work as expected. These tests can be triggered after each deployment to verify that the application is functioning correctly.
5. Monitor and adjust the automation process: It is crucial to monitor and adjust test scripts accordingly to ensure that DAST scans provide accurate and meaningful results and that the test scripts keep up with changes to the application.

By following these steps, you can automate the testing of complex interactions using DAST, which can help identify and fix security vulnerabilities and improve the overall security of your applications.

4) Identify and map out all entry points into your application

To identify and map out all entry points into an application, conduct scans on the application to identify how an attacker could gain access to the system. To do this using DAST, you should:

1. Define the scope of the DAST scan: Identify the specific parts of the application that will be included in the scan. This can consist of web applications, APIs, and other external interfaces.
2. Conduct a thorough survey: Scan the application to identify all the entry points, such as web pages, forms, and APIs. This can be done using a web crawler or spidering tool.
3. Identify the application’s attack surface: Once all the entry points have been identified, map out the application’s attack surface. This includes identifying all the different types of inputs (e.g. forms, cookies, query strings) and the corresponding validation checks.
4. Conduct vulnerability scans: Use DAST tools to test the identified entry points for known vulnerabilities including SQL injection, XSS, and other standard web application vulnerabilities.
5. Prioritize vulnerabilities: Once vulnerabilities are identified, prioritize them based on their level of risk and likelihood of exploitation to focus on fixing the most critical vulnerabilities first.
6. Continuously monitor the entry points: Repeat this process regularly to identify new vulnerabilities and attack vectors.

5) Identify all client-side controls you can use to protect against attacks

Here are some client-side controls that can be used to protect applications against attacks:

• Content Security Policy (CSP): A security feature that allows web developers to specify which content sources can be loaded and executed by the browser. This is helpful for preventing XSS and other injection attacks.
• Input validation: Ensure that user-supplied data meet specific requirements before the application uses it. Check for the correct data type, length, format, and range. By validating user input, applications can prevent attacks such as SQL and command injection.
• Output encoding: Convert user-supplied data into a safe format to display on the web page. This can include special encoding characters, such as angle brackets, to prevent injection attacks.
• Cross-Site Request Forgery (CSRF) token: A CSRF token is a unique value that is generated and sent to the client with each form or request. The client must include the token with each subsequent form submission or request to prevent unauthorized actions from being performed on the user’s behalf.
• Secure Cookies: Cookies are often used to store session data and other information on the client’s browser. Secure cookies are only sent over HTTPS connections, which helps to prevent eavesdropping and tampering.
• Whitelisting: Whitelisting is a technique in which a list of approved data sources or actions is defined, and any requests or data that do not match the approved sources are blocked. This helps to prevent injection attacks.

6) Integrate DAST with other tools to deliver a complete view of your web application environment

By integrating DAST with other tools, organizations can better understand the security of their web application environment. Combine different testing methods to identify vulnerabilities that may have been missed by using DAST alone and improve incident response time. Other tools you should integrate with DAST include:

• SAST (Static Application Security Testing): Helps identify vulnerabilities in the application’s source code
• Network vulnerability scanners: A comprehensive network vulnerability assessment helps to identify vulnerabilities in the network infrastructure that the application is built on
• Penetration testing: Helps identify how an attacker could exploit the vulnerabilities found by DAST and other tools
• Log analysis: Helps identify any suspicious or malicious activity on the application and network

7) Perform the test in a test environment first

A test environment replicates the production environment but is isolated and used for testing purposes. By conducting DAST scans in a test environment, organizations can identify and fix vulnerabilities before they are pushed to production, preventing security incidents and minimizing the risk of data breaches. Here are some steps for performing DAST in a test environment:

• Create a replica of the production environment, including all the necessary hardware, software, and data.
• Configure the DAST tool to scan the test environment according to the organization’s specific needs and requirements.
• Run the DAST scan on the test environment to identify any vulnerabilities or weaknesses that attackers could exploit.
• Review the results of the DAST scan and prioritize the vulnerabilities based on their level of risk and likelihood of exploitation.
• Fix the vulnerabilities identified by the DAST scan in the test environment.
• Repeat the DAST scan after the vulnerabilities have been fixed to ensure they have been appropriately addressed.

Carry on with peace of mind

DAST scanners are extremely useful in automating vulnerability identification in web applications. But DAST scanners do not provide code visibility, which can make it challenging for developers to identify and fix vulnerabilities. To carry on with peace of mind, integrate DAST with an automated security tool such as Spectral to spot coding mistakes, misconfigurations, and other potential sources of vulnerability that DevOps teams are accountable for. Create a free account and start building and shipping software faster, and safely, today.