What Is DAST and Why Does Your App Require Dynamic Application Security Testing?

Web and mobile applications are the driving force behind modern business, and it’s safe to say that their performance directly impacts a company’s revenue and profitability. On the other hand, the processing and storage of sensitive data makes software applications a preferred target for cyber criminals. Hence, one has to safeguard their apps in order to protect both the company’s and clients’ assets.

Though cybercrime grows at a consistent rate, it will skyrocket between 2024–2028, as per Statista. A report states that the global cost of cybercrime will probably reach $13.82 trillion by 2028. This being said, companies might expect more powerful cyberattacks and more risks related to cybersecurity. One of the ways to prevent or mitigate the majority of them is through implementing dynamic application security testing.

A word on application security

Before answering the “what is DAST” question, it is important to talk about application security first. For a detailed understanding, please see our article on AppSec, but for now, let’s quickly discuss its main concepts.

Application security can be defined as a set of tools, processes, and strategies aimed at securing an application throughout its SDLC (software development lifecycle). AppSec focuses on mitigating and preventing the most common cyberthreats (as listed by OWASP or CWE), and involves the use of application security controls – specialized measures for software protection. Examples of application security controls are:

• Access control
• Authentication
• Logging controls
• Data encryption

Also, application security implies regular application testing that comes in different forms: black box, white box, and gray testing. This is where the concept of DAST – dynamic security testing – belongs.

What is DAST?

DAST stands for dynamic application testing. If we address the DAST testing meaning, this process is aimed at examining the running app’s security via penetration tests and at finding potential vulnerabilities. An important thing to remember about DAST is that is applied to running applications only, and in this way, the process allows identifying both compile and run-time vulnerabilities within the app. However, DAST does not check the source code, so you’ll need to combine this testing process with static application security testing aka SAST (more on it below).

How does DAST work?

To perform dynamic application security testing, you’ll need a specialized DAST tool. This tool identifies various input fields of the app and sends to them malicious or sketchy inputs. In simple terms, a DAST testing tool intentionally tries to hack or compromise your application. Then, the tool analyzes the app’s response. Say, if an app crashes or a tool gets unauthorized access to the sensitive data, it will send a notification about the detected vulnerability. In this way, you’ll be able to quickly identify potential threats and will apply preventative measures in advance, thus eliminating the possible damage.

Key features of dynamic application security testing

Dynamic application security testing tools have a range of powerful and effective features that are worth discussing. Below, we list the most interesting ones.

Automated crawling 

As mentioned above, a DAST tool inspects an app on the subject of potential vulnerabilities. This process is called crawling and is performed automatically. Crawling includes mapping out the app’s structure, identifying inputs, and overall exploring its functionality. In this way, a tool performs a comprehensive analysis and creates a holistic image of the app and its components.

Detection of vulnerabilities

The core purpose of the DAST process is to detect vulnerabilities. While dynamic application security testing does not cover the source code, it’s enough to identify such common vulnerabilities as:

• SQL injection
• Cross-site scripting
• Insecure authentication mechanism
• XSS payloads
• Long input strings

Simulation of an attack

To detect abnormal behavior of the app, a DAST tool needs to kind of provoke it. For that, it will simulate an attack and see, whether an app responds in an unusual way or whether sensitive information will become exposed.

Examples of such attacks include fuzzing, parameter tampering, and session hijacking. It is important to note that attacks are performed on a running app, thus perfectly simulating a real-world environment, where a threat agent would first start an app to later hack it.

Reporting

After detecting vulnerabilities, a DAST tool then creates a report, where it listed what exact vulnerabilities were found, what activities caused them, and where they are located. This report is highly important for the overall app security as it helps safeguard it before any actual damage is done or before a real attack happens. Also, some DAST security tools provide actionable recommendations for remediation as part of such reports.

DAST testing pros and cons

Now that we are clear on dynamic application security testing definition, let’s address its pros and cons. While dynamic application security testing is undoubtedly helpful, it has certain limitations and challenges. Thus, it is important to understand both the benefits and challenges of DAST in order to successfully implement it in your processes.

The main benefits of DAST

Though we’ve already mentioned that DAST is aimed at improving the app’s security and reliability, let’s look at the DAST automated test benefits  in more detail:

• Early detention of vulnerabilities: a DAST tool can quickly and effectively detect both compile and runtime errors, thus enabling developers to fix existing issues before the app goes into production and gets exposed to potential threats.
• Reduced chance of a breach: since DAST informs about existing weak areas and vulnerabilities, developers can almost immediately apply the needed preventative measures. This, in turn, greatly reduces the risks of a cyberattack and helps avoid possible breaches.
• Suitable for any language and environment: due to the black-box testing technique of the DAST approach and its language agnostic nature, this method works perfectly well with an app written in any language and for any environment. 
• Low false positive rate: due to actually exploiting the detected vulnerabilities, DAST ensures that the ones found really pose a threat to the app’s security.
• Compliance with security standards and needed regulations: DAST serves as an additional security method for ensuring that the application meets all needed regulations and complies with the industry standards for security.

The main challenges of DAST

We’ve walked through the main pros of the DAST approach – now let’s address the main limitations and considerations of this method:

• Late implementation in SDLC: since DAST is applicable only for working applications, it can’t test the software during its development. Hence, some vulnerabilities and bugs will be more expensive to remediate.
• No access to source code: DAST tools do not have access to the source code, so if you use this testing method solely, some vulnerabilities may remain unnoticed.
• Limited code coverage: while the app is running, some of its parts are not executed – and thus, the DAST tool might miss them.

If you want to follow a holistic and comprehensive approach to testing the application, we recommend combining both DAST and SAST methodologies, so the app is tested in every aspect.

DAST security tools to consider

We’ve already answered the “what is dynamic application security testing?” question. Now, let’s look at the specialized tools. There are many available DAST tools out there in the market – below we review the most interesting and feature-rich solutions:

OWASP ZAP

Developed by OWASP, this tool is highly recommended and is praised for its functionality, flexibility, and efficiency. Being an open-source solution, OWASP ZAP grows with the needs of its community and is constantly evolving due to regular contributions. One more great thing is that it’s a free solution, though you might need to invest in additional customization or training.

Among the drawbacks to consider are lack of performance optimization and a steep learning curve for beginners. But overall, OWASP ZAP is a powerful and useful tool for dynamic security testing.

Acunetix

The main strength of this tool is automation of vulnerability detection. This makes Acunetix a great solution for frequent security scans, which is a must in many companies. In this way, you can save a great deal of time and minimize manual interventions while the tool rapidly scans through massive apps. 

As for the possible cons, Acunetix is quite pricey. It also focuses mostly on web security, thus leaving behind specific security aspects of other types of applications.

Portswigger Burp Suite

As an opposite to Acunetix, the Portswigger Burp Suite tool was designed specifically for manual testing, as an aid for pen testing. This tool helps identify those vulnerabilities that were overlooked by automated testing. It is therefore a perfect solution for those who want to deep-dive into manual testing and explore the app from A to Z.

While it’s very powerful and feature-rich, it can also be too complex for inexperienced users or small companies with simple apps. We therefore recommend this tool for companies with large-scale and complex applications that will benefit from a manual + automated testing combo.

Rapid7 AppSpide

One more DAST tool worth mentioning is Rapid7 AppSpide. What’s interesting about it is that Rapid7 AppSpide is great for integration in the DevOps lifecycle, which is present in most software development companies. Due to smooth and easy integration with most CI/CD tools, this solution allows effective app testing throughout most of SDLC. 

DAST vs SAST

Though this article is dedicated to dynamic application security testing, it’s important to discuss static application security testing too. By understanding both testing methods and the ways they differ, you will be able to build a robust testing strategy.

DAST best practices

Finally, let’s wrap up with a list of dynamic application security testing (DAST) best practices. While DAST itself is a powerful method for app testing, the use of these practices can improve the delivered testing results and can save you time and resources.

Select a suitable tool

Above we discussed several DAST tools and, as you can see, they vary in pricing, functionality, and even purpose (i.e., manual testing vs automated). Thus, carefully evaluate the needs and requirements of your specific application and see what tool suits these requirements the best. You can also consult with a knowledgeable software testing company to ensure that you select the most effective and appropriate DAST solution.

Consider the limitations and build the testing strategy correspondingly

Some companies rely on DAST solely when testing their apps and it leads to missed or unnoticed vulnerabilities. As a result, companies might face significant financial losses in case of a breach or another malicious attack.

To ensure all-round security, use dynamic application security testing together with other testing techniques (SAST, manual code review). In this way, you will be able to cover all aspects of the app, both the source code and components in execution.

Regularly update your DAST tools

Regular updating of any software leads to its better performance, higher reliability, and security. Thus, keep an eye on the latest updates and patches for DAST tools in use and make sure that you use the latest version.

Expert Opinion

DAST is a versatile tool for identifying potential vulnerabilities in web and mobile applications. It’s language-agnostic and can detect both compile-time and runtime errors. However, DAST has limitations, such as late implementation in SDLC and the inability to access source code. Combining DAST with other testing methodologies can help organizations take a holistic approach to security testing and better safeguard against evolving cyber threats. DAST is an essential tool for maintaining the security and reliability of software products in today’s digital landscape.

QA Engineer at SoftTeco

Svetlana Khaduskina

Summing up

Dynamic application security testing is an integral part of the overall testing process, aimed at improving the app’s security and closing vulnerability gaps. For maximal effect, we recommend partnering with an experienced testing team who will not only perform DAST but also provide valuable suggestions for future security improvements.