The Need for Application Security Testing

Security plays a key role whether you are onboarding customer workloads to the cloud, designing and developing a new product, or upgrading an existing service. Security is critical in every leg of the software development life cycle (SDLC).

Application security is important, as attackers and cybercriminals will target your software looking for vulnerabilities with the intent to steal data or disrupt operations. In the quest to cater to these challenges, the software industry came up with defending approaches to Application Security Testing which are broadly divided into three categories: SAST (static application security testing), DAST (dynamic application security testing), and IAST (interactive application security testing).

Application security testing in any of these three ways needs to be there for guarding the software application that has been built so far. The earlier developers catch and patch vulnerabilities in the SDLC by running Security as a Service (SaaS) tools, the less time-consuming and expensive it is to remediate issues. Combining DAST with SAST finds the vulnerabilities that are only seen while actually running a feature, giving you an even broader view of how secure your application really is. Implementing IAST takes this one step further since it incorporates something like an amalgamation of both SAST and DAST features to provide a wider scope for security analysis of the code

Static Application Security Testing (SAST)

SAST is a “white-box” testing mechanism, which analyzes the source code or binary files of an application to find security vulnerabilities. During the development stage, SAST tools scan the code and find out issues so developers can work on them very early in SDLC when the fixing cost is relatively less. The approach has been successful in the discovery of vulnerabilities like SQL injection, cross-site scripting (XSS), and other code-level flaws. Some examples of popular open-source SAST tools are SonarQube, Flawfinder, and FindSecBugs.

Why SAST Is Valuable

Early Detection

By testing the code upfront and uncovering bugs that existed even before they had started coding makes it possible for time and money to be saved or otherwise more serious issues to be evaded.

Detailed Insights

It helps to have access to more in-depth information about the vulnerabilities, including their locations in the code, which is critical for a fast correction.

Scalability

Tools like SAST can process much code and are thus usable in jobs of all sizes like continuous integration (CI) pipelines.

Challenges With SAST

False Positives

The false troubles with SAST are the ones that the system signals as a security risk, yet they are not.

Limited Scope

SAST can miss issues that come up at runtime or simple configuration mistakes.

Compilation Issues

The issues come from tools processing codes that are hard to compile, whether that be by the tools the code is written in or not.

Popular Open-Source SAST Tools

• SonarQube: This is a widely adopted open-source platform for continuous code inspection and security vulnerability detection. Check my article on how to set up and configure the SonarQube plugin to analyze Ansible playbooks and roles for security vulnerabilities and technical debt.
• Semgrep: Semgrep is a language-agnostic static analysis tool that identifies security vulnerabilities, bugs, and code quality issues.
• Brakeman: Brakeman is a SAST tool tailored for Ruby on Rails applications, scanning Ruby code for potential security vulnerabilities.
• Bandit: Bandit is an open-source SAST tool designed specifically for Python applications to identify security issues.

SAST vs SCA

To simply answer, SAST tools look for security vulnerabilities in the organization code while the Source Code Analysis(SCA) tools like Mend (formerly WhiteSource) check for the vulnerabilities in the open-source libraries or components used in the organization code. 

Dynamic Application Security Testing (DAST)

Black-box testing (DAST) is implemented to detect vulnerabilities in a live application, by emulating real-world attacks. DAST tools interact with the application through its user interface or APIs, emulating attackers trying to exploit found vulnerabilities without having access to source code. It is good for finding vulnerabilities that are only apparent when code runs, like improperly configured servers, weak authentication mechanisms, and mishandling of data. Examples of well-known open-source DAST tools are OWASP Zed Attack Proxy (ZAP), Burp Suite, and Arachni.

Why DAST Is Valuable

Runtime Analysis

DAST helps to resolve such issues that appear in a kind of situation when the application is live. This is very important for the detection of real-life attacks.

Broad Coverage

This technique can be used for the testing of different kinds of products such as web applications, APIs, and services.

Challenges With DAST

Late Detection

The entire development cycle may be concluded before testing with DAST so the fixing of any flaws that were found may be more time-consuming and difficult.

Limited Insight

It often does not provide all necessary information needed for troubleshooting, which may make finding the correct solution harder.

Popular Open-Source DAST Tools

• OWASP ZAP: A full-featured free and open-source DAST tool that includes both automated scanning for vulnerabilities and tools to assist expert manual web app penetration testing
• Nikto: A free open-source web server scanner that can be used to identify potential vulnerabilities
• Arachni: An open-source web application security scanner framework
• Wapiti: An open-source web application vulnerability scanner
• Code Intelligence Fuzz: An open-source fuzzing tool for web applications

Interactive Application Security Testing (IAST)

IAST is a gory hole approached with the "best of the worlds" since it includes the features of both SAST and DAST. IAST leverages instrumentation within the application to provide a comprehensive view of security vulnerabilities. IAST tools are good at monitoring the application's behavior during runtime, observing how the code interacts with external inputs and resources. IAST identifies those vulnerabilities related to complex application logic or unexpected runtime conditions that may be missed by the SAST or DAST tools. Open-source IAST tools include Contrast Security and Jaeger. It is designed to analyze an app in real-time as you interact with it, viewing the process from a "grey box" perspective.

Why IAST Is Valuable

Real-Time Feedback

IAST grants access to the live vulnerabilities while you are navigating through the application, thus being able to speed up the task of their resolution.

Low False Positives

IAST is more accurate when it comes to the exceptions made on purpose and program the logic before execution so its analysis of the code looks like a part of the code. In SAST or DAST, the tool just grasps through the scripts and is not attached to the risks exposition like IAST.

Early Detection

Like SAST, IAST can detect issues early in the development process.

Challenges With IAST

Complex Setup

Integrating IAST tools with the run-time environment of the application, is, without any doubt, a hard task.

Limited Coverage

IAST is unlikely to catch vulnerabilities that are not executed in the code when the process is in progress.

Popular Open-Source IAST Tools

• Contrast Community Edition (CE): This is one of the tools that is offered in the IAST range, which is only for one application and up to five users of the languages which are Java and .NET.
• HCL AppScan: A multiform testing mobile that includes not only static and dynamic but also interactive tests, it is the only one that supports languages and deployment even on the embedded platforms.

Importance of SAST, DAST, and IAST

These three application security testing approaches are essential for maintaining the security and integrity of software applications. SAST helps developers identify and fix vulnerabilities early in the SDLC, reducing the cost and effort required to remediate issues. DAST complements SAST by uncovering vulnerabilities that may only be visible during runtime, providing a more comprehensive assessment of the application's security posture. IAST further enhances this by combining the strengths of both SAST and DAST, offering a more holistic view of the application's security.

By leveraging a combination of these testing methodologies, organizations can significantly improve the security of their software applications, reducing the risk of successful cyberattacks and protecting their critical assets.

Bringing It All Together

The individual application security testing techniques include SAST, DAST, and IAST, and all these testing methods have different strengths that fit in specific stages of the development process. Using open-source tools such as GitHub CodeQL, OWASP ZAP, and Contrast Community Edition, developers can maintain their application's security without spending a lot of money. These tools integrated into the development process make it possible to identify the vulnerabilities soon, which simultaneously in sight, reduces the chances of getting hacked and also gives the software a fast track of software quality.

Eventually, an all-inclusive approach to application security testing will guarantee that you are not only identifying and fixing vulnerabilities but also creating a more resilient and safe application.

Further Reading

• SAST vs SCA- GitHub Blog
• Free for Open Source Application Security Tools - OWASP