SAST vs. DAST: Which to Choose?
In the world of application security testing, two types of testing reign supreme: DAST and SAST. Both toolings offer extensive benefits to any organization’s security stack by identifying vulnerabilities through comprehensive testing. Both focus on deeply analyzing source code and application functionalities to diagnose potential security issues accurately.
In this article, we will look at the age-old question of DAST vs SAST by understanding what each solution provides and the key differences in how and when to use them. We will also cover other available tools in the AppSec space that can be paired well with these solutions and provide a holistic approach to application security. With the agenda set, let’s get started.
What is Dynamic Application Security Testing (DAST)?
Dynamic application security testing, usually shortened to DAST, is a black box testing method for testing software that involves examining an application while it's running. This “black box” approach to application testing means that the testing tool has no knowledge of the application's internal interactions or design.
A DAST tool simulates attacks against the running application and observes its responses to identify vulnerabilities such as SQL injection or cross-site scripting vulnerabilities. Based on the outcome of each attack, the tool can help to find security vulnerabilities and determine whether the application is vulnerable and could be susceptible to a real malicious attack. These findings allow developers to fix the security defect before the source code is pushed out into the wild.
When to use use DAST?
A DAST tool should be used early on in the Software Development Lifecycle (SDLC). By moving this testing up earlier in the development process, also known as “shifting left”, the security issues can be fixed while active development is happening. A DAST tool can be a great help to all developers and allow them to discover security flaws, coding errors, and defects they've inadvertently put into the code. By nature, DAST tools find issues that are accessible and potentially exploitable, which is great for identifying high-priority items.
What is Static Application Security Testing (SAST)?
Static application security testing, usually shortened to SAST, is a type of “white box” testing that scans application code statically. SAST tools scan and analyze source code to find source code vulnerabilities by reading through each line of code. When a known vulnerability is identified through static analysis, developers are made aware so that they can remedy the security defect.
SAST tool scans static code of an application before the code is compiled. This also means that source code can be scanned even if it is not in a runnable state, meaning that a SAST solution can be implemented before the first line of code is committed. By doing this, any potential vulnerability that is introduced can be found immediately, versus being detected only once the code is in a runnable state.
When to use SAST?
Like DAST, SAST tools should also be used very early in the development process. Once you find a SAST tool that supports the language you are coding in, it can be moved into the development process. If a project involves writing code, a SAST tool is highly recommended to detect security vulnerabilities at the moment of inception.
Benefits of Combining SAST and DAST
Although SAST and DAST represent two different testing methodologies, combining SAST and DAST offers several significant benefits:
Comprehensive Security Testing: SAST and DAST together can identify a wide range of security vulnerabilities, including those that may not be detectable by one approach alone. This dual approach ensures thorough coverage of both static code and runtime behavior.
Early Detection: SAST helps identify security vulnerabilities early in the development process, allowing developers to address issues before they become ingrained in the codebase. DAST, on the other hand, identifies vulnerabilities in running applications, providing a real-world perspective on security flaws that can actually be exploited.
Improved Security Posture: By leveraging both SAST and DAST as well as other security testing methods, organizations can enhance their overall security posture beyond using just a single tool or method. Overall, this helps with reducing the risk of security breaches and ensuring holistic protection against potential threats.
Cost Savings: Identifying and fixing security vulnerabilities early in the development process can save organizations significant time and money. Early detection means fewer costly fixes and less disruption to the development lifecycle. By using both SAST and DAST together, you can detect vulnerabilities early and also understand which ones can actually be exploited, avoiding fixing defects which are false positives.
Choosing the Right Tools
Selecting the right SAST and DAST tools is essential for rounding out your application security testing stack. Here are some key factors to consider when looking at both types of tools:
Accuracy: Look for tools that can accurately identify security vulnerabilities with minimal false positives. Accurate tools help streamline the remediation process and ensure that critical issues are addressed promptly.
Coverage: Choose tools that support a wide range of programming languages and technologies. Comprehensive coverage ensures that all aspects of your application are tested for potential security weaknesses.
Integration: Consider tools that can seamlessly integrate with your existing development tools and workflows. Integration with CI/CD pipelines, version control, and other development tools within your developer workflow can help streamline the testing process.
Scalability: Select tools that can scale to meet the needs of your applications. While some tools may run well on smaller projects, testing with them at scale may not be as efficient. Scalable tools ensure that your security testing can grow with your application and support the technologies you plan to scale with.
Best Practices for SAST and DAST
Although you can just take any set of tools and toss them into the mix for developers to use, it's still best to have some sort of plan and method to the madness. When it comes to implementing SAST and DAST effectively, remember to follow these best practices:
Integrate SAST and DAST into the Development Process: SAST and DAST should be integrated into the development process to ensure that security vulnerabilities are identified and fixed early. This integration, often referred to as “shifting left,” helps catch issues before they become critical. Developers working on the code should feel empowered to use the tools and also be held accountable to ensure their usage.
Running SAST and DAST Regularly: Regular testing is essential to maintain a secure codebase. SAST and DAST should be run frequently to identify and address security vulnerabilities in a timely manner. One of the best ways to do this is to run these testing tools within CI/CD pipelines when a build is kicked off, as part of a pre-commit hook, or an automated pull request policy/branch protection rule.
Correlating Results: Don't use the results from each tool independently, instead try correlating the results of SAST and DAST tests to help identify potential security vulnerabilities more effectively. By combining insights from both tools, organizations can gain a better understanding of their security posture and more effectively triage any issues.
Implementing SAST and DAST Effectively
Beyond best practices, there are also some pointers to look at for effective implementation of SAST and DAST. A Successful integration of these technologies requires a combination of people, process, and technology. With this in mind, organizations should:
Develop a Comprehensive Security Testing Strategy: A well-defined strategy that includes both SAST and DAST is essential. This strategy should outline the goals, processes, and tools for security testing.
Train Developers and Security Teams: Training is crucial to ensure that developers and security teams are proficient in using SAST and DAST tools and techniques. Regular training sessions can keep teams updated on the latest security practices.
Integrate SAST and DAST into the Development Process and Workflows: Seamless integration of SAST and DAST into the development process ensures that security testing becomes a natural part of the development lifecycle. This integration helps catch vulnerabilities early and reduces the risk of security breaches.
Continuously Monitor Applications for Security Vulnerabilities: Once you've got everyone trained and your testing tools running, continuous monitoring is the next essential step in maintaining a secure application. Regular scans and real-time monitoring can help identify and fix vulnerabilities promptly, ensuring ongoing security.
By following these best practices and the considerations for implementing SAST and DAST effectively, organizations can significantly enhance their application security and protect against potential threats.
Wrapping up
Identifying any major or minor security flaw early on in the SDLC is the most efficient and scalable way to increase application security. With the abundance of tools available, adding SAST and DAST tools to your application's security arsenal is a great option. Even better, adding these tools to your organization's SDLC has never been easier, with many even offering deep customization and direct integration with CI/CD pipelines. As you can see, it's not so much about “SAST vs DAST” but ideally about how to layer the various tools together. Using these platforms is the best way to actively prevent and monitor many of the vulnerabilities and attacks outlined in the OWASP Top Ten. Keeping your applications secure requires multiple angles of prevention and monitoring to ensure a holistic approach to application security.
StackHawk offers a best-in-class DAST tool that is easy to configure and developer-friendly. The platform offers blazingly fast scans right in your CI/CD workflow, and an easy-to-understand report helps developers identify and remedy any security vulnerability that is discovered. To make things even easier, StackHawk easily integrates with Snyk, a popular SAST tool, to offer the best of both worlds by combining results between the two platforms. Ready to up your application security testing game? Sign up for StackHawk today to get started!
