SAST vs DAST: A Comprehensive Guide to Application Security Testing

In the domain of application security, two predominant testing methods stand out: Static Application Security Testing (SAST) and Dynamic Application Security Testing (DAST).

SAST tools inspect the code from the inside, looking for potential issues without actually running the app. Think of it like proofreading a document before it goes public.

DAST, on the other hand, assesses an application from the outside, simulating attacks on a live system much like a mystery shopper testing the security measures of a store.

Understanding these testing methods’ roles, strengths, and weaknesses is crucial for robust application security.

While SAST examines code at a static point in the software development life cycle, DAST evaluates the application in its dynamic, running state, uncovering different kinds of vulnerabilities that may not be visible in the code itself.

Applying both SAST and DAST provides a more comprehensive approach to identifying potential security issues.

By incorporating both methods in different stages of the development process, organizations can ensure a higher level of security and efficiency in their software development lifecycle.

Understanding Application Security Testing (AST)

Evolution of AST

The landscape of application security has transformed significantly with technological advancements. We witnessed the progression from basic code reviews to sophisticated automated testing tools.

Initially, security was often an afterthought; however, the rise in cyber threats has elevated the need for proactive measures.

Today’s AST integrates seamlessly with software development processes, shifting security “left” – closer to the development phase and becoming part of a continuous integration/continuous delivery (CI/CD) pipeline.

Importance of Application Security Testing in Software Development Lifecycle

Application Security Testing is crucial in identifying and mitigating security vulnerabilities in software applications.

By integrating AST into the Software Development Lifecycle (SDLC), we can identify and mitigate security risks early, reduce the cost of remediation, and ensure compliance with security standards.

This approach ensures that application security is not an afterthought but a fundamental component of the development process.

Early and continuous assessment of security risks allows us to address these concerns promptly, thus reinforcing the application’s defenses against potential threats.

In our exploration of Application Security Testing (AST), we focus on its essential role in the Software Development Life Cycle and examine the distinct types of AST: Static Application Security Testing (SAST) and Dynamic Application Security Testing (DAST).

However, Application Security Testing encompasses more than just SAST and DAST.

Many organizations utilize various other popular AST types to achieve comprehensive security testing and robust results, including Software Composition Analysis (SCA), Interactive Application Security Testing (IAST), Runtime Application Self-Protection (RASP), Penetration testing, and Mobile Application Security Testing.

• Static Application Security Testing (SAST): Involves analyzing application’s source code, byte code, or binary code to identify potential security vulnerabilities without executing the application.
• Dynamic Application Security Testing (DAST): Assesses an application while it’s running to identify security vulnerabilities. It operates as a black-box test, simulating real-world attacks.
• Interactive Application Security Testing (IAST): Combines elements of SAST and DAST to analyze an application’s code and typically needs to run from inside the application or its runtime environment in order to analyze the application’s code and behavior in real time during the testing phase, providing immediate feedback on potential security vulnerabilities.
• Software Composition Analysis (SCA): Focuses on identifying and addressing security vulnerabilities and licensing issues in third-party and open-source components used in application development. It also produces a bill of materials (BOM) which is an inventory of all assets of the application including open source, licenses, versions, and patch status.
• Runtime Application Self-Protection (RASP): Integrates directly into an application or its runtime environment to provide real-time protection by monitoring and responding to potential security threats as they occur.
• Penetration Testing: Involves simulating real-world attacks on an application to identify and exploit vulnerabilities, providing insights into the effectiveness of an application’s security measures.
• Mobile Application Security Testing: Specifically focuses on testing mobile applications for security vulnerabilities, addressing risks unique to mobile platforms, and risks commonly associated with mobile applications, such as insecure data storage, insufficient authentication and authorization mechanisms, and insecure network communications.

In this article, we will exclusively focus on SAST and DAST.

Static Application Security Testing (SAST)

Static Application Security Testing, or SAST, is our method of choice when it comes to identifying code-level vulnerabilities early in the software development lifecycle.

It’s a white-box testing technique that analyzes source code or compiled versions of code to find security flaws.

• When: Typically employed at the coding stage.
• What It Does: Analyzes source code, byte code, or binaries for security vulnerabilities without executing the program.
• Benefits: Can identify issues early in the development phase, leading to cost-effective remediation.

Working Principles of SAST

SAST tools work by examining the source code without executing the program. Their primary function is to create an abstract representation of the code and then traverse it, looking for patterns that indicate potential security vulnerabilities.

As we perform SAST, we’re effectively conducting a thorough review of the code’s DNA, uncovering issues that could compromise the application’s security posture.

Common Vulnerabilities Detected by SAST

Our SAST process is really good at finding various security issues, such as:

• SQL Injection: Vulnerabilities where untrusted data is used in a SQL command, leading to control of the database server.
• Cross-Site Scripting (XSS): Vulnerabilities that enable attackers to inject client-side scripts into web pages viewed by other users.
• Buffer Overflows: Security weaknesses where a program writes more data to a buffer than it is allocated for, which can lead to arbitrary code execution.
• Insecure Dependencies: Use of libraries or components with known vulnerabilities.
• Insecure Communication: Issues with the transmission of data over the network without proper encryption.
• Hard-coded Secrets: Sensitive information like passwords or API keys that are embedded directly in the source code.

Examining these vulnerabilities at the code level allows us to address security concerns before the application is deployed or reaches the dynamic testing phase.

Advantages and Challenges of SAST

Advantages:

• Early Detection: We catch flaws early in the SDLC, reducing costs and time needed to remediate.
• Comprehensive Coverage: SAST provides us with a wide coverage of the code base for potential vulnerabilities.

Challenges:

• False Positives: A known pain point is that SAST may report vulnerabilities that are not genuine threats, requiring manual review.
• Understanding Context: SAST does not execute the application, so it may overlook the context of how the code operates in a dynamic state.

Integration of SAST in the SDLC

Integrating SAST into our SDLC is a proactive step toward DevSecOps. By embedding SAST in the Continuous Integration pipeline, we ensure that every piece of code is scanned as it is written.

This practice aligns with our commitment to security and enhances the integrity of the software we develop. With techniques like SAST, we create more secure applications, protect our users, and maintain our reputation as developers of quality, reliable software.

Dynamic Application Security Testing (DAST)

As we dive into application security, an important method we use is Dynamic Application Security Testing, aka DAST

It’s like a detective for your running apps! DAST checks for security problems while your app is live, using Black-box testing techniques to offer real-time feedback. Let’s explore how DAST works!

Working Principles of DAST

DAST operates by simulating external attacks on a running application, just as an attacker would.

The principle around which it works is by communicating with an application’s exterior, sending various inputs and observing the outputs without the need to access the underlying source code.

It’s similar to testing the durability of a car by driving it rather than examining the engine blueprints. This black-box testing approach allows us to find runtime vulnerabilities that are otherwise hard to detect during earlier stages of development.

• When: Applied to running applications.
• What It Does: Simulates attacks against an application from an external perspective to uncover runtime vulnerabilities.
• Benefits: Provides insights into real-world attack scenarios and identifies issues that only surface when the application is operational.

Common Vulnerabilities Detected by DAST

When it comes to DAST, certain vulnerabilities stand out in terms of detection. Specifically, DAST is adept at uncovering runtime vulnerabilities such as:

• Security Misconfigurations: Poorly configured permissions on servers, services, and application frameworks.
• Authentication Issues: Problems with login and session management that could allow attackers to compromise passwords, keys, or session tokens.
• Cross-Site Request Forgery (CSRF): Attacks that trick a user into executing unwanted actions on a web application in which they’re authenticated.
• Sensitive Data Exposure: Inadequate protection of sensitive data such as financial information, leading to potential unauthorized access.
• Broken Access Control: Failures in user restriction settings that allow attackers to access unauthorized functionality or data.
• Session Management Flaws: Vulnerabilities that allow attackers to hijack user sessions.
• Unvalidated Redirects and Forwards: Allowing attackers to redirect users to phishing or malware sites.

These security problems often show up in a live setting, causing the most damage.

Advantages and Challenges of DAST

The advantages of DAST are significant. By interacting with the running application, DAST provides real-time feedback on issues that only become visible when an application is live.

This enables us to identify problems closer to how an attacker might experience them, reducing the chances of false positives that could occur with static analysis.

However, DAST comes with its own set of challenges, such as the need for a fully deployed application and potential difficulties in pinpointing the exact line of code containing the vulnerability.

Integration of DAST in the SDLC

Integrate DAST tools early in the development process, even during the staging phase, to allow for timely vulnerability identification.

It should be a part of the CI/CD pipeline, aligned with DevOps practices.

This approach help to ensure that security testing is a recurring part of development cycles, allowing for frequent and thorough assessments of the application in a state that closely mimics production.

While we usually think of DAST for security issues later in the game (during CD phase), I believe we can shake things up a bit.

Let’s bring Dynamic Application Security Testing (DAST) into the picture right from the start – in the Continuous Integration (CI) pipeline. How? Well, by using ephemeral environments that mimic the real deal.

Imagine testing most of your app’s functionalities in an environment hat closely resembles the actual production setup. That’s the magic of ephemeral environments.

By doing this security dance during CI, developers can catch and fix potential security hiccups early on.

Once we’ve got the basics covered, we can then take the full show to the staging or pre-production environments for a thorough run-through.

Comparative Analysis of SAST and DAST

In this section, we will discuss the distinct advantages and limitations of Static Application Security Testing (SAST) and Dynamic Application Security Testing (DAST), focusing on their security coverage, rate of false positives and negatives, efficiency, and the time and resource investments required.

Contrasting Security Coverage

SAST is an inside-out approach; it examines source code for security issues like buffer overflows without executing the code. It’s integral to the CI/CD pipeline and DevSecOps to ensure early detection.

And, DAST inspects a running application, simulating attacks to uncover vulnerabilities only visible during operation, making it complementary to SAST since it covers different aspects of security.

Assessment of False Positives and Negatives

SAST tools tend to report more false positives, which necessitates thorough reviews to avoid unnecessary fixes.

DAST, on the other hand, faces challenges with false negatives, potentially missing some vulnerabilities due to its reliance on an application in its dynamic state.

We must carefully curate test cases for DAST to minimize false negatives and validate SAST findings to remediate false positives effectively.

Efficiency in the Detection Process

Our use of SAST allows for integration earlier in the development stages, promoting efficient remediation and reinforcing the adage “Shift Left“.

DAST often complements SAST by applying fuzzing techniques to reveal issues in the integrated environment. The efficiency of both testing methodologies can enhance overall security robustness when appropriately timed in the development lifecycle.

Time and Resources Required

SAST requires investment in setting up and maintaining the tool within the build environment. However, this can save resources by catching issues before deployment.

Implementing DAST often demands a dedicated environment similar to production for accurate assessment but might reduce operational risks by discovering issues that only manifest post-deployment.

Balancing the two can ensure that we optimize our security coverage while managing time and resources efficiently.

Combining SAST and DAST for Better Efficiency

When we employ Static Application Security Testing (SAST) alongside Dynamic Application Security Testing (DAST), we leverage the strengths of both methods to create a more secure application environment.

SAST offers us early vulnerability detection directly from the source, which is ideal during the development phases, while DAST provides us with insights into runtime issues when the application is in a more mature state.

Advantages of a Combined Approach:

• Early Detection & Mitigation: By integrating SAST into the development process, we can identify and resolve security issues earlier, making the fixes less costly and reducing the risk of vulnerabilities making it to production.
• Comprehensive Analysis: By complementing this with DAST, we extend our security coverage beyond the code and identify weaknesses that only become apparent when the application is running.
• Workflow Integration: These tests can be woven into Continuous Integration/Continuous Deployment (CI/CD) pipelines for seamless operation, allowing for automatic and regular security checks.

Method	Ideal Use Case	Benefit to Efficiency
SAST	Development Phase	Early detection of vulnerabilities; easier & cheaper to fix
DAST	Post-Development	Insight into production-like environments; identifies runtime issues

Our goal is to ensure vulnerabilities are caught at every stage of the development cycle, maintaining a strong security posture while being efficient with our time and resources.

Use Cases: When to Utilize SAST vs. DAST or Both of Them

Each of them serves unique roles within a security testing protocol and understanding when to employ them can bolster our application’s defense mechanisms effectively.

SAST is ideally used when:

• In the development phase: SAST tools are capable of scanning an application’s source code before it’s running. We typically integrate these tools during the earliest stages of development to detect potential vulnerabilities.
• For white-box testing: Given our access to the internal structure, we can examine the codebase for issues like injection flaws or security misconfigurations.

DAST, on the other hand, is our go-to choice when:

• In the testing or production stage: DAST tools probe a running application, emulating the perspective of an external attacker to uncover issues that become apparent only when the software is operational.
• For black-box testing: We utilize DAST when we require an outsider’s view without the need to access the application’s source code.

When deciding on one or both testing methods, it’s crucial to consider the application type and objectives:

• Early in development: Employ SAST to rectify problems before they’re embedded into further iterations.
• Before deployment: Use DAST to catch what might have been missed and simulate real-world attacks.
• Both for full coverage: In critical security applications, combining SAST and DAST offers comprehensive insight—it’s like having both an architect and a building inspector.

Each has its place, and together, they form an integral part of a secure SDLC (Software Development Life Cycle).

Best Practices in Application Security Testing

Application Security Testing (AST) best practices are essential for safeguarding applications against security threats.

They involve defining security goals, selecting appropriate AST tools for SAST and DAST, managing vulnerabilities effectively, and integrating AST into DevOps.

Additionally, maintaining security over time through continuous monitoring, updates, and promoting secure coding practices among developers is crucial.

For a deeper understanding, click here to go to our Application Security Testing Best Practices article.

Tools for SAST, DAST, and Integration

When exploring Static Application Security Testing (SAST) tools, we consider the likes of :

• Checkmarx: Supports multiple programming languages and integrates with the CI/CD pipeline for early detection of security issues.
• SonarQube: One of the most popular SAST tool which focuses on continuous code quality and security, and supports a wide range of languages and integrations.
• Veracode: Offers static analysis along with dynamic and manual testing capabilities.
• Fortify Static Code Analyzer: Part of the Micro Focus Fortify suite, it provides comprehensive static analysis for security vulnerabilities.
• Klocwork: A static code analyzer for C, C++, C#, Java, JavaScript, and Python.

** To ensure a robust security posture, it can be beneficial to integrate Software Composition Analysis (SCA) tools alongside SAST tools in the CI pipeline to get a comprehensive view of both proprietary code vulnerabilities and potential risks associated with third-party components.

Software Composition Analysis (SCA) tools like Black Duck by Synopsys are specialized in identifying open-source components within codebases, along with their licensing information and any known security vulnerabilities.

Regarding Dynamic Application Security Testing (DAST), some of the well-known tools are :

• OWASP ZAP (Zed Attack Proxy): An open-source DAST tool that is maintained by the OWASP community.
• Acunetix: A fully automated DAST tool that can scan and report on a wide range of web application vulnerabilities.
• Burp Suite: A suite of tools for performing security testing of web applications, which includes both automated scanning and manual testing features.
• Micro Focus Fortify WebInspect: Offers dynamic analysis specifically designed for web applications.
• Tenable.io Web App Scanning: Provides automated vulnerability scanning for modern web applications.

Of note, we find that plugins, extensions, and applications, such as those available on GitHub, can significantly boost the effectiveness of SAST when we integrate them into our security testing factory.

Advanced Topics in AST

Some sophisticated components of Application Security Testing (AST) are essential in the current security landscape.

Emerging Technologies and Trends in AST

Our field is continuously evolving, and staying abreast with the latest technologies is pivotal. Currently, machine learning algorithms are being leveraged to refine AST tools, making them more intelligent in identifying complex security vulnerabilities.

Another trend is the shift towards cloud-based AST solutions, which offer scalability and ease of access across various platforms.

Emphasizing on the capabilities of AST tools to support wide range of programming languages and development frameworks assures us that our applications remain secure across different technologies.

AST for Modern Web Applications and APIs

Today’s web applications and APIs are highly dynamic, and traditional AST approaches may not suffice. When it comes to APIs, we focus on securing all types of interfaces such as REST, SOAP, and GraphQL.

This involves analyzing API endpoints for misconfigurations, authentication issues, and injection attacks.

Ensuring effective AST in modern applications involves adapting to microservices architectures and understanding the complex interactions between distributed systems.

Recommendations and Considerations

When selecting between Static Application Security Testing (SAST) and Dynamic Application Security Testing (DAST), it is critical for us to examine several key factors:

• Organizational Objectives: Consider what we aim to protect and prioritize; balance these aims with any limitations we may face, such as resources or time constraints.
• Team Collaboration: It is important to foster an environment where developers, security experts, and stakeholders actively communicate and cooperate to integrate security throughout the development lifecycle.
• Continuous Evolution: Security landscapes and technologies are constantly changing. We must commit to ongoing learning to adapt our processes and tools to stay ahead of emerging threats.
• Regulatory Adherence: Always account for the necessary compliance, governance, and risk management requirements pertinent to the industry and nature of the software.

Based on these factors, we should adopt a strategic approach to application security:

1. Early Intervention: Employ SAST in the early stages of development to identify and mitigate issues before the application is running.
2. Real-time Assessment: Utilize DAST to test applications in their running state, which is crucial for uncovering issues that only manifest during operation.
3. Hybrid Methodologies: Consider the benefits of integrating both SAST and DAST to achieve comprehensive coverage.
4. Customized Implementation: Tailor the balance of SAST and DAST tools to our organization’s specific needs, rather than adopting a one-size-fits-all strategy.

Considering these factors helps us build a safer development process that fits our main goals and adjusts to changing security needs.

Additional Resources

To further enhance our understanding of SAST and DAST, we’ve compiled a collection of useful resources

Learning and Collaboration:

• Join online communities such as OWASP to engage with other professionals and share insights on SAST and DAST.
• Participate in webinars and online courses that focus on security testing methodologies.

Documentation and Articles:

• SAST: For a deeper dive into Static Application Security Testing, the Veracode article gives a comprehensive overview of the approach.
• DAST: Gain a practical perspective on Dynamic Application Security Testing through the insights available in GitLab’s comparison of SAST and DAST.

Integration Strategies:

• For strategies on how to combine SAST and DAST for maximum security, consider the expertise shared by Snyk.

Wrapping up

In our exploration of application security testing, we’ve addressed the distinctive strengths and complementarities of Static Application Security Testing (SAST) and Dynamic Application Security Testing (DAST).

It’s important for us to recognize that neither SAST nor DAST is a standalone solution. Instead, we maintain a holistic perspective on application security, recognizing the place both SAST and DAST hold in our toolbox.

Frequently Asked Questions

What limitations should one consider when implementing Static Application Security Testing (SAST) and Dynamic Application Security Testing (DAST)?

SAST cannot identify runtime vulnerabilities and may generate false positives. DAST requires a running application and may miss statically detectable vulnerabilities.

What are the cost implications of implementing SAST, DAST, or both?

Implementing both SAST and DAST incurs higher costs but provides more comprehensive coverage. The investment might yield lower long-term expenses by catching and mitigating issues early.

What is Software Code Analysis (SCA) and how does it differ from SAST and DAST methodologies?

Unlike SAST, which analyzes proprietary code for security flaws, or DAST, which tests running applications for vulnerabilities, SCA specifically targets the security and management of third-party and open-source libraries integrated into an application.

Are there any industry-specific considerations for selecting SAST or DAST tools?

Certain industries, like finance and healthcare, have strict regulatory requirements that may influence the selection of SAST or DAST tools for compliance purposes.

How can organizations effectively integrate SAST and DAST tools into existing development workflows and environments?

Effective integration requires carefully planning the insertion points of these tools in the development lifecycle and ensuring they do not disrupt workflows.

What considerations should organizations evaluate when selecting tools for integrating SAST and DAST?

Organizations should consider a tool’s compatibility with programming languages in use, integration capabilities with existing development tools, and the capacity to scale with the organization’s growth.

What resources, training, or expertise are recommended for implementing and managing integrated SAST and DAST solutions?

A combination of internal or external security specialists, proper training for development teams, and an understanding of the tools’ operational requirements are crucial.

How can organizations measure the effectiveness and ROI of a combined SAST and DAST approach?

Assessment can be done by tracking the number of vulnerabilities detected and fixed, the time taken to remediate, and the reduction in the incidence of security breaches.

How IAST differ from the Combination of SAST & DAST?

IAST offers a more integrated and immediate approach to security testing by providing real-time feedback during the development and testing phases, while a hybrid approach involves running SAST and DAST tools separately and then combining the results manually or through specialized software.

Why do people prefer SAST and DAST over IAST?

Both SAST and DAST are well-established methods with a wide range of available tools and a strong understanding within the security community.

Additionally, some organizations may find it challenging to integrate IAST into their existing development and testing processes, the setup process can be complicated and require the assistance of a specialist, which can influence their preference for SAST and DAST.

Ultimately, the choice between SAST, DAST, and IAST depends on the specific needs and constraints of individual organizations, as well as the nature of the applications being tested.

Can DAST tools also identify vulnerabilities which are typically detected by SAST tools?

Yes, it is true that Dynamic Application Security Testing (DAST) tools can potentially detect some vulnerabilities that Static Application Security Testing (SAST) tools also identify, such as SQL Injection, Cross-Site Scripting (XSS), and Buffer Overflows.

However, it’s essential to understand the fundamental differences in their approaches and capabilities. Adopting both tools in a comprehensive security strategy ensures a thorough assessment across different stages of development and deployment.