SAST Vs. DAST Vs. EASM: Selecting the Right Tools for You

Modern cybersecurity is littered with too many acronyms that sometimes leave even seasoned professionals scratching their heads. If your task is to protect a website or web application, the abbreviations that could interest you include SAST, DAST, and EASM.

In this article, we delved into the specifics of these three cybersecurity approaches and explained each one so you can better understand which one best suits your needs.

Table of Contents

• SAST vs. DAST vs. EASM: A Quick Rundown
• What Is SAST?
• What Is DAST?
• What Is EASM?
• SAST vs. DAST vs. EASM: Which One Should You Choose?

SAST vs. DAST vs. EASM: A Quick Rundown

Here’s the TL;DR version of the differences between SAST, DAST, and EASM.

What Is SAST?

Static application security testing, or SAST, is among the most frequently used application testing techniques, which involves analyzing an application’s source code to identify potential security vulnerabilities. It is typically part of the software development process.

SAST is essentially a white-box testing method, meaning that it examines the internal structure and logic of the code. As such, it can only identify vulnerabilities within the source code,  promoting the development of more secure and robust code.

How Does SAST Work?

SAST approaches application testing from the inside. The software does not need to run for the test to start since SAST scans the application’s source code to find flaws.

Specifically, the tool traces data flows using various techniques, such as:

• Signature-based pattern matching: In this technique, SAST tools look for common injection patterns in the application source code.
• Semantic analytics: This technique enables the tool to examine the code’s context, logic, and dependencies.
• Taint analysis: This entails tracing the input data’s route to see if attackers can manipulate the end result with malicious inputs. 

SAST tools would then send security alerts to the development team for vulnerability remediation whenever issues are detected.

In addition to the above-mentioned techniques, developers may perform custom static code analysis queries to search for specific vulnerabilities.

When Should You Use a SAST Solution?

SAST is performed during the early stages of the software development lifecycle (SDLC), specifically while developers are still writing the code for the app. Checking the code before the app is actually built is an essential step in any software development process so developers can fix bugs in the code that can result in vulnerabilities.

Testing with SAST tools like SonarCube often is a part of a continuous integration and continuous delivery pipeline and precedes the actual building of the app from source code.

What Is DAST?

Dynamic application security testing, or DAST, is a method for testing applications that involves simulating attacks to identify vulnerabilities that may be missed during regular testing.

Unlike SAST, DAST doesn’t look at the source code, but rather tests an application’s behavior while it runs. As such, it can uncover vulnerabilities that only manifest during application execution. For instance, it can detect authentication issues and misconfigurations after use.

How Does DAST Work?

DAST operates as a black-box testing method. It does not require access to the application’s source code nor does it need any information about the app. Therefore, it sees the application as an outsider does and simulates attacks like external hackers do.

A DAST scanner examines the application’s external infrastructure, mapping out all web pages, links, and other resources that could serve as an attack entry point. It then tests all detected input fields using strings or content similar to what attackers typically send.   

When the scanner receives an unexpected response from the application (e.g., an error message or sensitive information) that indicates or confirms the presence of a web application vulnerability, it records the response and sends this data as an automated alert to the appropriate teams for remediation.

When Should You Use a DAST Solution?

DAST is best performed at the latter stages of SDLC, right before deployment, since you want to detect vulnerabilities before the application is released to the public. So, in the CI/CD pipeline, developers often use DAST after the app has been built and deployed to a development or staging environment.

However, many also run regular DAST scans on production to ensure that previously unknown vulnerabilities do not plague the customer-facing version of the software. 

What Is EASM?

External Attack Surface Management, aka EASM, is the continuous process of identifying, assessing, and prioritizing vulnerabilities in applications, cloud infrastructures, and other Internet-facing systems. It is used to identify all the external assets of an organization and aims to improve the organization’s overall security posture and reduce the number of potential attack entry points.

Unlike SAST and DAST, which focus on one application at a time, EASM provides visibility over all the applications of an organization. It covers all digital resources that are reachable on the Internet and scans them for vulnerabilities, including the assets you didn’t even know existed, such as, for example, that server with an old and vulnerable app version that still allows access to a database.

EASM scans your infrastructure continuously, letting you know if there’s any security issue with your live app in production or any other external-facing asset.

How Does EASM Work?

EASM involves four stages that are incorporated into EASM solutions. The first is attack surface discovery, which involves identifying and cataloging all your Internet-facing assets and their vulnerabilities. At this stage, EASM tools scan the Internet for external resources attributable to your organization (e.g., domain names, subdomains, IP addresses, open ports, cloud accounts, and SSL certificates) and check them thoroughly for any security issue.

EASM tools then rank the discovered vulnerabilities using a combination of risk scoring standards and methods, such as the Common Vulnerability Scoring System (CVSS), Exploit Prediction Scoring System (EPSS), and the Known Exploited Vulnerabilities (KEV) Catalog maintained by the Cybersecurity and Infrastructure Security Agency (CISA). The goal is to help security teams focus on the most critical and relevant vulnerabilities first.

The third stage of the EASM process involves security risk remediation. At this stage, security teams swoop in and develop remediation strategies for the ranked vulnerabilities. Some organizations use the integration feature of EASM solutions to access project management and support ticketing platforms for easier tracking of remediation activities.

Lastly, EASM involves continuous attack surface monitoring. Since EASM is a cyclical process, the tool continuously performs the first three stages and notifies the users if it discovers something new. This step is critical since organizations constantly add new assets and, as a result, take on new vulnerabilities throughout their business operation.

When Should You Use an EASM Solution?

EASM tools should be constantly used for your released app and all the other external-facing assets. The EASM approach should be an ongoing, continuous process, not a one-time or occasional task.

SAST vs. DAST vs. EASM: Which One Should You Choose?

Each tool has unique strengths and ideal use cases, and is excellent when applied to its corresponding stage. To better grasp how DAST, SAST, and EASM differ, here’s a quick summary.

• Use SAST to analyze code for errors to avoid creating vulnerabilities.
• Use DAST to test an app while in staging and production to find vulnerabilities that may have slipped through the cracks before malicious actors can find them.
• Use EASM to catalog and monitor all external-facing assets related to your app and your whole digital infrastructure and continuously detect vulnerabilities. 

What If I Don’t Have the Budget for All of Them?

If your organization doesn’t have the budget for everything and needs to cut something out, you will likely want to keep SAST and EASM.

SAST tools like Sonar Qube are often inexpensive. Meanwhile, EASM platforms can, to some extent, replace a DAST tool while covering the rest of your Internet-facing assets, such as your marketing website and cloud databases.

Additionally, EASM tools like Attaxion can be even cheaper than a DAST tool despite having broader functionality.

Ready to see how Attaxion can amp up your application security? Schedule a customized demo now.