Software applications have changed how we work and conduct everyday business. Web applications in particular increasingly handle sensitive data, which has, in turn, amplified data privacy and security issues. Ensuring the security of web applications and infrastructure is therefore vital to organisations. Protecting sensitive data, staying safe from emerging threats and vulnerabilities, and navigating legal and regulatory compliance are all critical parts of almost every IT department.

Safeguarding these applications is a multifaceted challenge: no solution can protect them completely. However, different security tools and measures exist to help ensure that applications are optimised for security during development and even after they’re live. To do that, techniques such as Application Security Testing (AST) help find and fix any vulnerabilities in the code at every stage of the software development life cycle (SDLC).

Web applications are particularly vulnerable to security breaches, with a recent study confirming attacks on web applications were possible in 98% of cases. Similarly, research from Verizon shows that web application attacks contribute to 26% of all data breaches. Each security testing method has its own unique approach to inspect and mitigate application vulnerabilities. Over the years, these methods have evolved to address the ever-growing security risks.

Before you settle on a security tool to employ, here are the main types of security tool that you may consider in order to help testers and developers identify vulnerabilities in the code at different points of development – with their pros and limitations.


Dynamic Application Security Testing (DAST)

Dynamic Application Security Testing (DAST) is a security approach used to dynamically evaluate the security of your web environments, APIs, and applications. DAST is also referred to as “black-box” testing, as it operates from an external perspective (that of an “attacker”), without peeking into the application’s source code. It can be conducted automatically through vulnerability scanning platforms or as a tool to assist with manual security testing methods, such as penetration testing.

DAST tools work by mimicking application interaction with external systems, real users, and bots that would interact with your applications and websites in the real world. They use real or virtualized web browsers to interact with a web application, looking for indicative vulnerability signs, performing tests, and loading pages. With their automated nature, they need to handle elements like CSRF tokens and authentication – these are important for testing and accessing API endpoints and web pages, so ensure your DAST tool does this well.

Interestingly, DAST is the most straightforward security test to deploy with minimal configuration, since you just input a URL and initiate the scanning process. With a good DAST tool you should be able to fine-tune the process to get precise results.

According to research, the DAST market has risen with an expected 2.56 billion dollars in 2023, expected to grow at a CAGR of 18.74% and reach 6.04 billion dollars by 2028.


Use case: How to discover Cross-Site Scripting (XSS) with DAST

An e-commerce website, for instance, allows users to input ratings and reviews for products. An attacker may input malicious JavaScript code into the review text box to exploit this vulnerability. If the website fails to sanitize and validate user input, the malicious code can be stored in the website’s database. DAST tools can identify this vulnerability by interacting with the application like a regular user.

During that scan, they may feed in the JavaScript code in the product rating box and observe how the application handles it. If the application fails to process the feed incorrectly and instead reflects the code to the users, it would mean that the application can be exploited via XSS. The DAST tool would report the specific endpoint or page where the XSS vulnerability exists, as well as giving details on how it can be exploited, in order to guide remediation efforts.


Pros of DAST

  • Tools simulate real-world attacks by testing the application in its running state. They provide an external perspective, similar to how an actual attacker would approach them.
  • Tools can scan an entire application, including the front end, back end, and APIs.
  • Detects vulnerabilities like cookie manipulation or cross-site scripting and SQL injection
  • DAST is versatile because it is suitable for different tech stacks, since it is language-independent
  • Many DAST tools support automated scanning, enabling regular and continuous security testing as part of the development process
  • DAST tools can assess threats in third-party interfaces
  • Evaluates the whole application and the systems, giving a wider attack surface assessment
  • It validates permissions, ensuring privilege levels are isolated
  • DAST attempts to breach encryption algorithms from an external position
  • The tools understand arguments and function calls


Cons of DAST

  • With massive projects, there may be a need to acquire parallel applications and custom infrastructure instances
  • DAST does not highlight code-level vulnerabilities
  • They may generate false positives, which may need manual verification


Static Application Security Testing (SAST)

Static Application Security Testing (SAST), also known as “white-box” testing, is an alternative approach that involves examining an application’s source code for possible vulnerabilities. The name, white box testing, stems from the tools providing a comprehensive look at the application’s inner workings. SAST tools are deployed during the development phase of the SDLC to ensure any security concerns are detected and addressed from the earliest stages.

SAST tools have a deep look into the application’s DNA. SAST incorporates tools like basic Integrated Development Environment (IDE) plug-ins that signal insecure syntax to standalone code analysers that dig into entire code storage, mimicking data flows. Since these tools dissect the source code, they are naturally language-specific, and to provide complete coverage of a multi-language codebase may require using different, often incompatible, SAST tools.


How to discover XSS with SAST

The tool digs into the source code, inspecting how the ratings are processed closely within the application.

In the analysis, SAST spots a section of code where user inputs are involved directly into HTML content without any encoding or validation, potentially opening the space for XSS attacks. Then, the SAST tool generates a warning, marking out the specific lines of code that pose an XSS risk.


Pros of SAST

  • SAST tools do not need program execution, which makes it possible to identify vulnerabilities before the application gets into production
  • SAST tools can be deployed early on in the development process; thus, the issues can be resolved before they are deployed to even a staging environment. Early remediation is generally cheaper.
  • With SAST, developers get real-time feedback, often in graphical representation of the issues found, helping resolve the problem immediately
  • SAST analyses the whole application codebase, including inactive and unreachable code paths


Cons of SAST

  • SAST tools may generate a high number of false positives due to their need to synthesize data for testing, which may lead to incorrect warnings and wasted time
  • SAST tools are not equipped to assess the values of most arguments of call dynamics since it is a static analysis method
  • SAST tools do not have access to runtime data or user input, which means they may miss certain vulnerabilities that only become apparent during actual usage.
  • These tools are language-specific, which makes it challenging to build and maintain multi-language codebases and may need various tools for every used language.
  • These tools may also need help understanding the frameworks or libraries’ degrees like REST or API endpoints.


Interactive Application Security Testing (IAST)

IAST falls under the “gray-box” testing category, a mix of black-and-white box testing. These tools are most effective in QA phases where automated functional tests happen and are often used with other security testing tools.

Similar to DAST, IAST tools dynamically operate to identify vulnerabilities during the application’s runtime. However, IAST tools operate from within the application server and delve deeper into the code, similar to SAST.


Use Case: How to identify Cross-Site Scripting with IAST

Using the same example of an e-commerce website with product ratings and reviews – when you use the IAST tool to perform security testing, it works from within your application’s server. It closely examines how user-generated content is deployed and processed in real time. The tool might input a rating with malicious code to imitate a possible XSS attack. As users continually post comments and ratings, the tool observes how the application handles the content carefully.

To identify a vulnerability as XSS, the tool detects that the application fails to validate and sanitize user-generated content properly, thus allowing malicious JavaScript to execute and possibly affect other users. The IAST tool would give concise and detailed information about where the vulnerability is located within the code, such as the specific lines of code that require attention.



  • You get real-time results, hence allowing immediate response
  • It is ideal for microservices applications, which gives room for effective API testing.
  • There is a more comprehensive analysis of configuration, data flow, the usage of frameworks and libraries, source code, and runtime control
  • These tools provide information about the root causes of the vulnerabilities, like the exact location within the code where there is a problem


Cons of IAST

  • Most of these tools are exclusive in that they create a dependency on the tool’s supplier for updates and support.
  • They support only a limited programming language
  • IAST tools can be quite resource intensive within a production environment.
  • The tools can generate false positives and false negatives
  • Implementing IAST effectively requires a certain level of expertise, which means a learning curve for development and security teams


Which is the best Security Tool?

Adopting SAST, IAST, and DAST can seamlessly work together to provide the most complete coverage, if the budget allows. Combining these tools enhances coverage and reduces the risk of vulnerabilities in production. However, the upfront cost, as well as the time commitment to resolving false positives and maintaining the tooling may not be practical or the best choice in all cases.

It is more pragmatic and common to tailor an organisation’s security program to include the testing types that best fit your organization while considering the pros and cons of each.

If you’re looking for a solid starting point, DAST is a dependable choice with its ease of set-up and use, with minimal or no integration time or engineering commitment.

Reach out if you’d like a demonstration of the AppCheck DAST scanning tool.


About AppCheck

AppCheck is a software security vendor based in the UK, offering a leading security scanning platform that automates the discovery of security flaws within organisations websites, applications, network, and cloud infrastructure. AppCheck are authorized by the Common Vulnerabilities and Exposures (CVE) Program as a CVE Numbering Authority (CNA).


Additional Information

As always, if you require any more information on this topic or want to see what unexpected vulnerabilities AppCheck can pick up in your website and applications then please get in contact with us: info@appcheck-ng.com.

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