What is Software Composition Analysis (SCA)?

Software is like processed food– it’s usually impossible to determine what went into making it just by consuming the end product. Without reading the label, you can’t ascertain the precise ingredients of an Oreo any more than you can tell just by looking at an application exactly which libraries, modules, and other third-party code the software developers may have used to create it.

That’s where software composition analysis (SCA) is a powerful solution. It enables organizations to analyze applications' contents and determine whether any may pose cybersecurity risks, making SCA an important part of software supply chain security.

What is SCA?

Software composition analysis (SCA) is the practice of determining which software components make up an application. The primary purpose of SCA is to identify third-party open source code that developers used when creating the application. This includes code that they added directly to the application’s codebase, as well as third-party libraries, modules, or other dependencies that the application requires to function as intended.

How does software composition analysis work?

Software composition analysis works by running automated scans of applications, then identifying components similar to those associated with open source codebases. After finding matches, SCA tools generate detailed reports that list the components and their associated vulnerabilities, providing developers and security teams with insight into the origins of the code within the application. Some tools can generate a software bill of materials (SBOM), a standardized inventory that is increasingly important for regulatory compliance.

SCA scans usually work best when they assess application source code since code in this form allows for comparison of raw instructions to code within open source repositories. However, some SCA tools can also scan application binaries– meaning source code that has been compiled–and identify similarities between binary components and binary open source code.

Why SCA matters

Based on the insights that SCA offers, businesses are better positioned to handle two main risks:

1. Security vulnerabilities: SCA scans can flag third-party software components affected by Common Vulnerabilities and Exposures (CVEs), meaning they are vulnerable to attack.

2. Licensing risks: In some cases, using third-party code within an application requires an organization to comply with the software licenses that govern the original code. Failure to comply could result in legal action.

In a perfect world, running software composition analysis scans would not be necessary because developers would create SBOMs that meticulously document which third-party components they use when developing software. In the real world, however, developers don’t always generate SBOMs; even if they do, they can easily overlook some application components when creating an SBOM. They may also forget to update an SBOM when they modify applications in ways that change their contents.

SCA safeguards against these oversights by allowing organizations to create inventories of an application’s “ingredients” and identify any risky components they did not know about. Even for teams that maintain SBOMs for their applications, SCA is valuable as a secondary line of defense against software supply chain risks.

Benefits of SCA

By helping organizations find third-party content within an application, software composition analysis enables a range of benefits:

• Enhanced supply chain security: The most important benefit of SCA is stronger software supply chain security, by helping teams identify vulnerable components within their software supply chain.

• Streamlined regulatory compliance: SCA can help organizations meet regulatory compliance requirements, especially those (such as NIS2) that include rules for managing software supply chain risks.

• Dependency analysis: SCA can help to identify which libraries, packages, or other dependencies must be present within a deployment environment for an application to run properly. In addition to identifying vulnerable dependencies, this information is useful in cases where the dependency lists created by developers are inaccurate and IT teams need to install additional software to ensure they can deploy an application.

• Licensing compliance and code ownership: SCA helps businesses avoid accidentally violating the licenses that govern third-party code they use. It’s also useful for identifying any code within an application that the business didn’t develop itself and therefore can’t manage under its own licenses. 

• Keeping code up-to-date: By tracing third-party code within an application back to its source, SCA makes it easier for developers to update the code they use when the code also changes within its original source. For example, if an application depends on an open source library and the library’s developers release a new version, the application’s developers can update their code accordingly.

SCA security tools and solutions

Most software composition analysis security tools are part of commercial platforms, although a few (such as Aqua Security's Trivy) are available as free and open source software. When selecting an SCA solution, consider:

• Whether you need SCA scanning alone or want a tool that can perform other types of security scans (like SAST and DAST).

• If you need to run an SCA scan on the application source code, binary code, or both.

• How accurate and comprehensive your SBOMs are, and whether you are using SCA tools simply to double-check for oversights your SBOMs may have missed, or to create SBOMs from scratch.

• Which SBOM format you would like your SCA solution to use when reporting the contents of an application

Securing the software supply chain with Chainguard

When you use secure container images from Chainguard, you don’t need to worry about unknown components lurking in your software supply chain. Chainguard goes beyond traditional container security by providing comprehensive build-time SBOMs that capture the complete software composition of your containers, including the "software dark matter" that typically goes undetected. While most SCA tools only see your application dependencies, Chainguard's SBOMs are generated as code during the build process, documenting every component, build tool, and transient dependency that contributed to your final image.

When you run SCA scans on Chainguard container images, you get complete visibility into your software supply chain rather than just the surface-level components. You'll know exactly what's in your containers and can trace every piece back to its source.

SCA scans are still valuable as a way of discovering risks within your application code that you may not know about, but Chainguard keeps the core supply chain secure for you, so there’s less for SCA to flag.

Learn more by contacting the Chainguard team.