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Application Security

Topic 5: SAST / DAST / IAST

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Understanding the difference

Static Application Security Testing (SAST):

  • SAST involves analyzing an application's source code, byte code, or compiled version for security vulnerabilities without executing the code.

  • SAST tools scan the codebase for patterns, coding practices, and potential vulnerabilities based on known security rules and best practices.

  • Example: Let's consider a simple web application written in Python using the Flask framework. A SAST tool would analyze this code and identify security vulnerabilities, such as SQL injection, due to unsanitized input in the SQL query.

    Here's a code snippet for a login function:

Dynamic Application Security Testing (DAST):

  • DAST involves testing an application in a running state by sending requests and observing responses to identify security vulnerabilities.

  • DAST tools simulate real-world attacks by interacting with the application through its user interface or APIs.

  • Example: Continuing with the previous example of a web application, a DAST tool would send HTTP requests to endpoints, such as /login endpoint with different input parameters, to test for vulnerabilities like SQL injection, cross-site scripting (XSS), and insecure direct object references (IDOR).

Interactive Application Security Testing (IAST):

  • IAST combines elements of both SAST and DAST by analyzing the application's code and behavior during runtime.

  • IAST tools instrument the application code to monitor its execution and identify real-time security vulnerabilities.

  • Example: Modifying the login function from the previous example to incorporate IAST instrumentation. The security_monitor instrumented code would monitor inputs for potential security vulnerabilities such as SQL injection or XSS during runtime.

    Here’s the code snippet:

Pros and Cons

Static Application Security Testing (SAST)

Pros:

  • Early Detection of Vulnerabilities: SAST analyzes the source code or compiled binaries before execution, allowing for the early detection of vulnerabilities during the development phase.

  • Comprehensive Coverage: It scans the entire codebase, including third-party libraries and dependencies, providing extensive coverage of potential security vulnerabilities.

  • Integration with Development Workflow: Integrates into the development workflow, providing developers with immediate feedback on security issues and facilitating quick remediation.

  • Low False Positive Rate: SAST tools typically have a low false positive rate, reducing the likelihood of developers wasting time on non-existent vulnerabilities.

Cons:

  • Limited Context: SAST tools analyze code in isolation and may lack context about the application's runtime behavior, leading to false negatives and missing specific vulnerabilities.

  • Manual Review Required: Results provided often require manual review by experienced security professionals to differentiate between real vulnerabilities and false positives, which can be time-consuming.

  • Limited Coverage of Runtime Vulnerabilities: The primary focus is on code-level vulnerabilities and may miss specific runtime vulnerabilities, such as configuration issues or input validation errors.

Dynamic Application Security Testing (DAST)

Pros:

  • Real-World Simulation: DAST simulates real-world attacks by interacting with the application in a running state, providing insights into how attackers can exploit vulnerabilities.

  • Detection of Runtime Vulnerabilities: It identifies vulnerabilities that may only manifest during runtime, such as authentication bypasses, session management flaws, and insecure configurations.

  • Automated Scanning: DAST tools automate the scanning process by sending HTTP requests to the application and analyzing responses, enabling efficient testing of web applications and APIs.

  • Scalability: Scalability can be achieved by testing multiple applications or environments simultaneously, making it suitable for large-scale security assessments.

Cons:

  • Limited Coverage of Code-Level Vulnerabilities: DAST primarily tests the application's runtime behavior and may miss specific code-level vulnerabilities that can only be detected through static analysis.

  • High False Positive Rate: DAST tools generate a high false positives ratio, requiring manual verification and validation of findings.

  • Limited Support for Authentication and Session Handling: DAST may encounter challenges in testing authenticated or session-based functionality, leading to incomplete coverage of specific security controls.

Interactive Application Security Testing (IAST)

Pros:

  • Real-Time Monitoring: IAST tools monitor the application's code and behavior during runtime, providing real-time feedback on security vulnerabilities as they occur.

  • Deep Code Analysis: IAST allows deep analysis of execution paths, data flows, and dependencies to identify vulnerabilities accurately.

  • Integration with Development Workflow: IAST seamlessly integrates into the development workflow, providing developers with immediate feedback on security issues and enabling quick remediation.

  • Low False Positive Rate: IAST tools typically have a lower false positive rate, reducing the burden on developers and security teams to validate findings manually.

Cons:

  • Performance Overhead: IAST may introduce performance overhead on the application, potentially impacting its runtime performance and scalability.

  • Limited Coverage of Third-Party Libraries: IAST, at times, has limited visibility into vulnerabilities within the application's third-party libraries or components, requiring additional measures to ensure comprehensive coverage.

  • Complex Configuration: IAST requires complex configuration and setup to monitor and analyze the application's behavior accurately, potentially increasing deployment and maintenance overhead.