SAST vs. DAST: What’s the Difference?

Scanning Tools

Publish Date

Jun 17, 2021

Written by

ZN Logo for Blog


Tagged with

  • DevSecOps
  • DevOps
  • AppSec
  • SAST
  • DAST
  • Tools

Considering the threats posed by the digital world, organizations today must think about security and the way it affects their software. With business outcomes and revenue on the line, setting up and running an effective application security (AppSec) program is no longer just nice to have—it’s imperative. Practitioners need to identify vulnerabilities in their applications to prioritize risk and mitigate risk, a goal that can only be achieved through comprehensive AppSec testing.

Two AppSec testing methodologies that exist in today’s security realm are SAST and DAST. While SAST investigates applications from the inside out, DAST works from the outside looking in.

Definitions = Knowledge

Static application security testing (SAST) follows a white-box method of testing, where the logic of the software is assessed from the inside out and code is scanned before it’s deployed.  Performed mostly by developers, SAST scanning focuses on the internal structures of data, design and code to test the known workings of the software, rather than just the functionality. This process makes fixing vulnerabilities more affordable because they have been identified early in the SDLC. While SAST tools are not perfect, they do allow users to:

  • Locate known patterns of vulnerabilities
  • Automate the testing process
  • Scale an AppSec program
  • Read and action output data
  • Prioritize risk and speed remediation

Dynamic application security testing (DAST) is a black-box method, mostly performed by software testers, where the internal structure, program or code is hidden and/or unknown. This type of external software testing happens while an application is running in production to see how it behaves in a dynamic state. A DAST test can spot configuration mistakes and errors, including specific application issues, while providing valuable insight into security issues before deployment.

While DAST testing is critical, it shouldn’t be done in isolation from SAST because it’s far more expensive to fix vulnerabilities after a software build is complete and software is running. DAST tools are used later in the software life cycle, enabling users to:

  • Examine an application while it’s running
  • Expose potential vulnerabilities
  • Mimic a cyber attack
  • Scale an AppSec program
  • Facilitate an automated testing process

SAST + DAST = The Right Choice for Testing

With so many security scanning tools on the market, it’s hard to know which ones are best to use in an AppSec program. To truly minimize risk and pave the way to a more robust AppSec program, SAST and DAST tools should be combined during the testing process. Because both tools have unique benefits and drawbacks, they complement one another well when blended into a hybrid approach.

When multiple tools are used in AppSec testing, several challenges emerge. Each tool produces different reports with varying naming conventions and severity ratings—and a lot of them. This level of data can be overwhelming to developers who are tasked with innovation at the speed of DevOps. Cross-referencing results from these two tools allows you to identify which potential vulnerabilities found by the SAST tool are truly exploitable, as identified by the DAST tool. Only then is it possible to gain a full picture of organizational risk and which vulnerabilities present the most threat.

ZeroNorth = Tool Optimization

The ZeroNorth DevSecOps platform simplifies the use and central management of AppSec tools by combining the results of multiple static and dynamic analysis tools – as well as other tools used to identify vulnerabilities, such as software composition analysis (SCA) –  to help practitioners normalize results. Our platform centrally manages all the AppSec tools and then automatically unifies vulnerability findings, making them usable and operational for security and development teams.

ZeroNorth automatically ingests all scanning data into a central database and normalizes it into a common risk framework. It then aggregates, dedupes and compresses related issues to remove redundancy, minimize noise (such as false positives). Through this data refinement process, ZeroNorth can compress thousands of issues from multiple tools into a concise list of vulnerabilities—in some cases achieving a compression rate of 90:1 — making it far easier and simpler to triage, prioritize and fix them, as an integral part of their DevSecOps process.

By removing the complexity of managing AppSec tools and their findings, ZeroNorth helps speed up remediation processes, thus improving developer productivity and product quality—all without slowing deployments into production.

To learn more about how ZeroNorth can help your organization simplify and manage an AppSec program while paving the way to true DevSecOps, visit our website or contact us for more information.

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