Dynamic application security testing (DAST)

Dynamic application security testing (DAST) is a method of testing the security of an application while it’s running. DAST tools test web applications during their operating states to find security vulnerabilities using simulated attacks, such as SQL injection, cross-site scripting, and insecure server configuration. This application security (AppSec) testing type mimics a malicious hacker to find security issues in the running application, so developers can fix them before the application is deployed to the public.

Why is DAST important for application security?

Although billions of dollars have been invested into AppSec tools, 85% of applications still contain known vulnerabilities, with most breaches occurring at the application layer, according to the GitHub software security guide.

DAST tools are a type of security tool that can be used as part of an application security program. DAST assists developers during the software development lifecycle (SDLC) by helping them catch vulnerabilities that can be exploited by malicious attacks. Vulnerabilities can range from simple coding errors to more complex issues such as insecure settings or misconfigured environments. Identifying vulnerabilities early on helps businesses protect against data breaches, tarnished brand reputations, and lost customer trust.

How do DAST tools work?

DAST tools empower development teams to look at the application from a black-box security perspective, which is very close to the attacker mindset. DAST mimics the same techniques that malicious attackers—who don’t know the application’s infrastructure, architecture, or code—use to find application vulnerabilities. The DAST tool:

• Performs a crawl to pick up on application layer attack points like links, cookies, and URL parameters.

• Creates a map of the web applications’ pages and issues.

• Audits what it discovered and simulates different kinds of malicious attacks to uncover security vulnerabilities.

• Alerts the development team when it finds a vulnerability in an application.

Types of DAST

There are two types of dynamic application security testing. Automated DAST, described in the bullet points above, uses software to scan the application for vulnerabilities and replicate the attacks. For more complex situations, security experts use manual DAST procedures to test for vulnerabilities that automated DAST might miss. To combat sophisticated hackers, development teams might use a combination of both automated and manual DAST.

Although automated DAST is typically faster and more efficient, it might not be able to identify all vulnerabilities in a web application and may generate false positives. Manual DAST tends to be more accurate because it can be tailored to the web application, but it’s more time consuming and resource intensive.

Benefits of DAST

Also known as a web application vulnerability scanner, DAST scanning helps application development teams safeguard their web applications from the most damaging attacks, including ones that give hackers access to sensitive data such as credit cards and customer information.

Dynamic application security testing is an effective tool for identifying externally visible security issues and runtime problems that make it possible for hackers to carry out the following web application attacks:

• SQL injection, one of the most common types of web-based attacks, where the attacker takes control of the web application’s database.

• User privilege issues attacks where malicious employees gain access to sensitive information.

• Memory corruption, which lets an attacker leak sensitive information or execute code.

• Cross-site scripting, where attackers inject their own code to steal sensitive information.

• Insecure server configuration attacks to expose critical or sensitive data.

After DAST alerts the development team that the scan identified security vulnerabilities, the team works to remediate the issues and protect their company’s brand and customers from the damaging consequences caused by cyberattacks and data breaches.

DAST Pros

• Mimics a real-world malicious hacker to Identify security vulnerabilities that only occur in running applications. Other AppSec tools typically don’t find these issues.

• Generates few false positives (reports of vulnerabilities that aren’t present) compared to other methods.

• Can be run on any application since it doesn’t need access to source code. Therefore, one DAST tool can support all the development team’s applications.

DAST Cons

• Might require security experts to run tests and interpret reports.

• Scans might take a long time to complete.

• Can’t pinpoint the specific location of problematic code because it doesn’t work with the application’s source code.

DAST vs SAST

Dynamic application security testing (DAST) is different from static application security testing (SAST):

• DAST tools scan programs while they are executing to find security issues in the running application.

• SAST tools scan application source code or binary code when the application is not executing to identify potential vulnerabilities based on design or implementation.

Some SAST tools even scan code as it’s created. For example, a SAST code scanning product is natively embedded in GitHub Advanced Security (GHAS) to examine code as it’s written and integrate fixes natively into the developer workflow. This helps developers find and fix security issues in their code earlier to automate and scale application security.

Developer teams looking to maximize application security use a combination of DAST and SAST tools to test their web applications. This best practice strengthens security by giving developers a comprehensive view of application vulnerabilities, both from an “outside in” hacker perspective with DAST and an “inside out” developer perspective with SAST.

How to use DAST tools

DAST tests are run in real time to help developers identify and fix security issues before the application is launched. The most effective strategy is to run DAST tests early in the SDLC, when it’s less costly and time-consuming to remediate vulnerabilities. Once the web application is in production, DAST continues to search for vulnerabilities, and sends alerts to the right people when remediation is needed.

Build secure applications with DAST

Web application cyberattacks are serious threats to businesses. By mimicking a malicious attacker who is trying to break into an application to steal data, DAST scanning exposes the most damaging security vulnerabilities, so development teams can fix them before the application is launched into production.

Using tools like DAST to stay ahead of security issues is a key component of GitHub Security. Designed to help developers take a proactive security approach, GitHub Security natively embeds security tools directly into the DevOps workflow, including:

• Code scanning scans for security issues as code is written and integrates fixes natively into the developer workflow.

• Secret scanning prevents fraudulent use of leaked secrets that may have accidentally been pushed into code.

• Supply chain security uses software composition analysis to catch vulnerable dependencies before they’re introduced into the codebase.

• Security overview provides a centralized, single view of security risks across the entire enterprise.

In addition, third-party security capabilities are available through GitHub Actions, to give developers the freedom and extensibility to automate, customize, and execute their software workflows in the same place they code. This functionality empowers developers to use third-party SAST engines, DAST, infrastructure as code scanning (IaC), and container scanning.

Together, GitHub Security, DAST, and third-party tools empower developer teams to secure their software and custom code across the software lifecycle.