Application security testing is a critical component of modern software development, ensuring that applications are robust and resilient against malicious attacks. As cyber threats continue to evolve in complexity and frequency, the need to integrate comprehensive security measures throughout the SDLC has never been more essential. Traditional pentesting provides a crucial snapshot of an application’s security posture, but when integrated across the SDLC, it allows for early detection and mitigation of vulnerabilities, reducing the risk of costly post-deployment fixes and enhancing overall security.

While the specifics for security testing vary for applications, web applications, and APIs, a holistic and proactive applications security strategy is essential for all three types. There are six core types of testing that every security professional should know about to secure their applications, regardless of what phase they are in in development or deployment.

In this article, we will explore these six types of application security testing methods essential to keep your software secure from potential threats while meeting your business and operational requirements. These include:

1. Penetration testing for the SDLC
2. Dynamic Application Security Testing (DAST)
3. Static Application Security Testing (SAST)
4. Interactive Application Security Testing (IAST)
5. Fuzz Testing for APIs
6. Application Security Posture Management (APSM)

Application Security Testing Methods

There is no doubt that pentesting is a crucial aspect of security testing, but often is a point-in-time assessment that simulates attacks to identify vulnerabilities. In contrast, the other pentesting methods are more integrated into the application development and maintenance processes, providing continuous or more frequent pentesting and scanning assessments, focusing on different aspects of the application lifecycle, and using various automated and manual techniques.

Before we review the six main types of application security testing, organizations often want to understand the difference between these methods and penetration testing. Each of these methods has distinct characteristics and objectives, differing from traditional pentesting in various ways. Here’s a quick breakdown of each method compared to pentesting; however, these methods are often integrated or overlap with penetration testing, and all are part of a proactive approach to application security testing at different stages of the development lifecycle.

1. Penetration Testing for the SDLC: 

Penetration integrated into the Software Development Life Cycle (SDLC) involves conducting security assessments at various stages of the development process. This ensures vulnerabilities are identified and mitigated early, before the application is deployed. Pentesting can be done during the design, coding, testing, and deployment phases to continuously assess the security posture of the application.

• Integrated into the Software Development Life Cycle (SDLC) to identify vulnerabilities throughout development
• Conducted at various stages (e.g., design, development, testing, deployment)
• Aims to catch and fix vulnerabilities early in the SDLC, reducing the cost and effort of remediation
• Should be an automated, continuous, and iterative assessment compared to traditional pentesting (periodic)

Top Three Benefits: 

• Early Detection and Mitigation of Vulnerabilities: Identifying security issues early in the SDLC prevents them from progressing to later stages, where they become more costly and difficult to fix.
• Cost Efficiency: Fixing vulnerabilities early in development is less expensive than addressing them post-deployment, saving resources and reducing remediation costs.
• Continuous Improvement and Compliance: Regular pentesting throughout the SDLC promotes continuous security improvements and ensures compliance with industry standards and regulations, building customer trust.

2. Dynamic Application Security Testing (DAST)

Dynamic Application Security Testing (DAST) is a type of security testing that analyzes a running application from the outside to identify vulnerabilities. It simulates external attacks to discover security flaws in the application’s runtime environment without accessing the source code.

• Tests applications from the outside in, simulating an external attack.
• Performed on running applications without access to source code.
• Focuses on identifying runtime vulnerabilities like SQL injection, XSS, etc.
• Provides immediate feedback on security issues during the testing phase.

Pentesting:

• May involve both external and internal assessments, including source code reviews
• Can encompass a broader range of attack vectors and techniques
• Less automated and more reliant on the skills and creativity of the human tester

Top 3 Benefits:

• Runtime Vulnerability Detection: DAST identifies vulnerabilities that manifest during the application’s execution, such as SQL injection and cross-site scripting (XSS).
• Immediate Feedback: Provides real-time feedback on security issues, allowing developers to quickly address and fix vulnerabilities.
• No Source Code Access Needed: DAST can be performed without access to the application’s source code, making it suitable for testing third-party applications or legacy systems.

3. Static Application Security Testing (SAST)

Static Application Security Testing (SAST) involves analyzing an application’s source code, bytecode, or binary code for security vulnerabilities without executing the program. It helps identify issues like insecure coding practices and code-level vulnerabilities early in the development process.

• Analyzes source code, bytecode, or binary code for vulnerabilities without executing the program
• Performed early in the development process (during coding)
• Helps identify issues like buffer overflows, insecure coding practices, and other code-level vulnerabilities
• Provides insights into code quality and security best practices

Pentesting:

• More focused on the application in its deployed state and less on the underlying code
• Identifies vulnerabilities that can be exploited in a running system rather than just in the code

Top 3 Benefits:

• Early Detection of Code-Level Issues: Identifies vulnerabilities and insecure coding practices during the coding phase, reducing the risk of security flaws progressing to later stages.
• Improved Code Quality: Encourages adherence to secure coding standards and best practices, leading to overall better-quality code.
• Cost-Effective Remediation: Fixing vulnerabilities during development is more cost-effective than addressing them after deployment.

4. Interactive Application Security Testing (IAST)

Interactive Application Security Testing (IAST) combines elements of both SAST and DAST by analyzing an application’s code and monitoring its behavior during runtime. IAST provides real-time feedback on security issues as the application is exercised, offering a comprehensive assessment of both code and runtime vulnerabilities.

• Combines elements of both SAST and DAST by analyzing code and monitoring application behavior during runtime
• Provides real-time feedback on vulnerabilities as the application is exercise.
• More comprehensive as it can detect issues that manifest during execution and at the code level
• Integrated into the development and testing process for continuous monitoring

Pentesting:

• Usually performed as a separate activity from development, providing a point-in-time assessment
• Relies on manual and automated techniques but lacks the continuous, real-time feedback loop of IAST

Top 3 Benefits:

• Comprehensive Vulnerability Detection: Detects vulnerabilities at both the code level and during runtime, providing a thorough security assessment.
• Real-Time Feedback: Offers immediate insights into security issues, enabling rapid identification and remediation.

Continuous Monitoring: Integrated into the development and testing process, IAST supports continuous security assessment and improvement.

5. Fuzz Testing for APIs

Fuzz Testing, or Fuzzing, for APIs involves sending random, malformed, or unexpected data to an API to identify vulnerabilities, crashes, or unexpected behaviors. It helps uncover issues that might not be found through traditional testing methods

• Involves sending random or malformed data to APIs to identify unexpected behaviors or vulnerabilities
• Effective at finding buffer overflows, crashes, and other stability issues
• Typically, automated and can uncover flaws that may not be identified through traditional testing methods

Pentesting:

• May include some elements of fuzz testing but is broader in scope
• It focuses on finding and exploiting a wide range of vulnerabilities, not just those related to input handling

Top 3 Benefits:

• Uncover Hidden Vulnerabilities: Identifies buffer overflows, crashes, and other stability issues that traditional testing methods might miss.
• Automation-Friendly: This can be automated, allowing for extensive testing of various input scenarios without manual intervention.
• Improved API Robustness: Enhances the overall robustness and reliability of APIs by ensuring they can handle unexpected inputs gracefully.

6. Application Security Posture Management (APSM)

Application Security Posture Management (APSM) focuses on continuously managing and maintaining the security posture of applications throughout their lifecycle. It involves monitoring, vulnerability management, policy enforcement, and compliance checks to ensure ongoing security and adherence to industry standards.

• Focuses on managing and maintaining the security posture of applications throughout their lifecycle
• It involves continuous monitoring, vulnerability management, policy enforcement, and compliance checks
• Aims to ensure ongoing security and compliance with industry standards and regulations
• Often integrates with various security tools and processes for a comprehensive approach

Pentesting:

• Provides a snapshot of an application’s security at a specific point in time
• Doesn’t offer the continuous monitoring and management aspect of APSM

Top 3 Benefits:

• Continuous Security Monitoring: Provides ongoing assessment of application security, ensuring vulnerabilities are identified and addressed promptly.
• Enhanced Compliance: Helps maintain compliance with security regulations and standards, reducing the risk of regulatory penalties.
• Proactive Risk Management: Supports proactive identification and mitigation of security risks, improving the overall security posture and reducing potential attack surfaces.

The six types of application security testing methods are not isolated practices; rather, they complement and reinforce each other to provide a comprehensive security assessment. DAST evaluates the application in its running state, identifying runtime vulnerabilities, while SAST analyzes the source code to catch security issues early in development. IAST combines these approaches, offering real-time insights during runtime and code analysis, making it a powerful tool for continuous security assessment. Fuzz Testing for APIs focuses on ensuring API robustness against unexpected inputs, while APSM provides ongoing management and monitoring of the application’s security posture, ensuring compliance and proactive risk mitigation. Together, these methods create a robust security framework that can adapt to the dynamic nature of software development and the evolving threat landscape.

In conclusion, the integration of diverse application security testing methods is vital for developing secure, resilient applications. Each method addresses unique security challenges, and their combined use ensures comprehensive coverage, early detection, and continuous improvement. By leveraging the strengths of all of the security methods, security professionals and their organizations can build a proactive AppSec security approach that complements one another, secure your applications against current threats, and also adapts to future risks.

Ref: https://thehackernews.com/2024/07/6-types-of-applications-security.html