What is a software bill of materials (SBOM)?

Introduction

A software bill of materials (SBOM) is a detailed, structured list of all components, libraries, and dependencies within a software application. It serves as an inventory—an ingredients list of sorts— providing insight into the various software components, their origins, dependencies, and licenses. This is especially important in the context of open source software, where applications often rely on many third party dependencies.

An SBOM enables organizations to manage security risks, improve transparency, and respond quickly to vulnerabilities by identifying all components in use. It is a critical tool for maintaining a secure software development process.

Why SBOMs are essential for open source software security

The vast majority of modern software applications depend on open source components. SBOMs are crucial for tracking these dependencies, ensuring that any vulnerabilities in open source libraries can be identified and addressed quickly. Since open source software is made available under an “as-is” licensing policy, security and licensing risks may go unnoticed without a clear inventory of software components.

Incorporating SBOMs into an organization's security strategy helps streamline the identification of outdated or vulnerable open source components, allowing for quicker remediation.

Three key benefits of using SBOMs

1. Improved transparency: SBOMs provide a comprehensive view of all the software components, including their licenses and version schemes, ensuring full transparency throughout the software supply chain.

2. Enhanced security: by maintaining an up-to-date SBOM, organizations can track and monitor vulnerabilities in open source components, mitigating the risk of cyberattacks.

3. Compliance with regulations: many government regulations and guidelines, such as Executive Order 14028 in the U.S., require software vendors to provide SBOMs to demonstrate secure software development practices.

The leading SBOM formats

There are several widely recognized formats used to generate and manage SBOMs. These formats standardize how SBOMs are created and shared across organizations, making it easier to exchange and interpret data about software components. The leading SBOM formats are Software Package Data Exchange (SPDX) and CycloneDX.

• SPDX: SPDX is a widely adopted standard for creating SBOMs. It is supported by organizations such as the Linux Foundation and provides detailed metadata about software components, including licenses and copyright information.

• CycloneDX: CycloneDX is a lightweight SBOM standard that focuses on security vulnerabilities and risk management. It is designed to work seamlessly with various security and vulnerability tools, making it a popular choice for cybersecurity professionals.

Conclusion

SBOMs are a crucial tool for modern software development, particularly for managing the security and transparency of open source components. By providing a detailed inventory of software dependencies, SBOMs help organizations mitigate security risks, respond to vulnerabilities, and comply with regulatory requirements. As open source software continues to dominate the software landscape, adopting SBOM practices is essential for maintaining a secure and resilient software supply chain.