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Your Guide to AppSec Tools: SAST or SCA?
By: Alyssa Shames, Senior Product Marketing Manager
With a market that is so saturated with various tools - we're often asked, "What's the difference between SAST and SCA?" The short answer: they address completely different problems.
Static Application Security Testing (SAST) defined
SAST is a security testing tool that's been around for over a decade and was developed when most code was proprietary and copy/pasting snippets was a huge problem. Its primary use case is reporting security and quality issues in proprietary, static source code (internally written). This is different from Dynamic Application Security Testing (DAST), which flags run-time issues.
Software Composition Analysis (SCA) defined
On the other hand, SCA is a newer technology solving a different problem - open source governance. SCA supports more modern development environments where software is procured by developers from an upstream supply chain. SCA tools scan applications to identify open source components, creating a software bill of materials (SBOM) and ultimately surface risk using metadata about overall component quality (vulnerabilities, licensing, architecture, etc.). It's primary use case is compliance and developing dependency management workflows.
SAST vs. SCA - What's the difference?
When comparing SAST and SCA, it comes down to what they are analyzing - SAST analyzes proprietary code while SCA analyzes open source.
Binaries + Source Files vs. Source code - SAST tools only analyze the source code/compiled code. This can prove problematic. SAST requires access to the source files, and in some cases organizations no longer have access to that or they have access to it but it can't be compiled because it is missing key libraries. You can't patch an issue if it's not represented in the code.
SCA tools scan files and binaries, which provides more coverage for an application. While you could use SAST tools to read through the source code of OSS libraries and identify security flaws, unless you want to make code contributions (and convince the maintainers to accept them), that won't solve the problem.
SCA tools enable developers to select a better open source version that complies with policy and is also designed to work in a DevSecOps environment. SCA scans are quick and can be embedded within CI/CD to fail builds or even further left in the developer's IDE or SCM via pull requests to fix open source components that a developer introduced.
Early vs. Everywhere - SAST tools find vulnerabilities early-on in the development cycle whereas SCA tools provide continuous monitoring for vulnerabilities at every stage of the SDLC.
False Positives - If code is improperly configured, SAST tool scanning will result in a high number of false positives. SCA tools are known for working fast, so suited for releasing early and often, and with a low false positive rate.
There is no one-size-fits-all answer, but a best practice is to choose a best-of-breed SCA or SAST solution. One that provides end-to-end coverage, whether you're working in proprietary or open source code. At Sonatype, we focus on automating open source governance at every stage of the SDLC with precision to eliminate false positives and false negatives and have partnered with a leading SAST provider to analyze proprietary code.
Learn more about key technology considerations when selecting SCA solutions by downloading this Gartner Technology Insight for SCA report.