What is an SBOM?
The Linux Foundation | 15 June 2021
The National Telecommunications and Information Administration (NTIA) recently asked for wide-ranging feedback to define a minimum Software Bill of Materials (SBOM). It was framed with a single, simple question (“What is an SBOM?”), and constituted an incredibly important step towards software security and a significant moment for open standards.
From NTIA’s SBOM FAQ “A Software Bill of Materials (SBOM) is a complete, formally structured list of components, libraries, and modules that are required to build (i.e. compile and link) a given piece of software and the supply chain relationships between them. These components can be open source or proprietary, free or paid, and widely available or restricted access.” SBOMs that can be shared without friction between teams and companies are a core part of software management for critical industries and digital infrastructure in the coming decades.
The ISO International Standard for open source license compliance (ISO/IEC 5230:2020 – Information technology — OpenChain Specification) requires a process for managing a bill of materials for supplied software. This aligns with the NTIA goals for increased software transparency and illustrates how the global industry is addressing challenges in this space. For example, it has become a best practice to include an SBOM for all components in supplied software, rather than isolating these materials to open source.
The open source community identified the need for and began to address the challenge of SBOM “list of ingredients” over a decade ago. The de-facto industry standard, and most widely used approach today, is called Software Package Data Exchange (SPDX). All of the elements in the NTIA proposed minimum SBOM definition can be addressed by SPDX today, as well as broader use-cases.
SPDX evolved organically over the last decade to suit the software industry, covering issues like license compliance, security, and more. The community consists of hundreds of people from hundreds of companies, and the standard itself is the most robust, mature, and adopted SBOM in the market today.
The full SPDX specification is only one part of the picture. Optional components such as SPDX Lite, developed by Pioneer, Sony, Hitachi, Renesas, and Fujitsu, among others, provide a focused SBOM subset for smaller supplier use. The nature of the community approach behind SPDX allows practical use-cases to be addressed as they arose.
In 2020, SPDX was submitted to ISO via the PAS Transposition process of Joint Technical Committee 1 (JTC1) in collaboration with the Joint Development Foundation. It is currently in the approval phase of the transposition process and can be reviewed on the ISO website as ISO/IEC PRF 5962.
The Linux Foundation has prepared a submission for NTIA highlighting knowledge and experience gained from practical deployment and usage of SBOM in the SPDX and OpenChain communities. These include isolating the utility of specific actions such as tracking timestamps and including data licenses in metadata. With the backing of many parties across the worldwide technology industry, the SPDX and OpenChain specifications are constantly evolving to support all stakeholders.
The Sony team uses various approaches to managing open source compliance and governance… An example is using an OSS management template sheet based on SPDX Lite, a compact subset of the SPDX standard. Teams need to be able to review the type, version, and requirements of software quickly, and using a clear standard is a key part of this process.
Hisashi Tamai, SVP, Sony Group Corporation, Representative of the Software Strategy Committee
“Intel has been an early participant in the development of the SPDX specification and utilizes SPDX, as well as other approaches, both internally and externally for a number of open source software use-cases.”
Melissa Evers, Vice President – Intel Architecture, Graphics, Software / General Manager – Software Business Strategy
Scania corporate standard 4589 (STD 4589) was just made available to our suppliers and defines the expectations we have when Open Source is part of a delivery to Scania. So what is it we ask for in a relationship with our suppliers when it comes to Open Source?
1) That suppliers conform to ISO/IEC 5230:2020 (OpenChain). If a supplier conforms to this specification, we feel confident that they have a professional management program for Open Source.
2) If in the process of developing a solution for Scania, a supplier makes modifications to Open Source components, we would like to see those modifications contributed to the Open Source project.
3) Supply a Bill of materials in ISO/IEC DIS 5962 (SPDX) format, plus the source code where there’s an obligation to offer the source code directly, so we don’t need to ask for it.
Jonas Öberg, Open Source Officer – Scania (Volkswagen Group)
The SPDX format greatly facilitates the sharing of software component data across the supply chain. Wind River has provided a Software Bill of Materials (SBOM) to its customers using the SPDX format for the past eight years. Often customers will request SBOM data in a custom format. Standardizing on SPDX has enabled us to deliver a higher quality SBOM at a lower cost.
Mark Gisi, Wind River Open Source Program Office Director and OpenChain Specification Chair
The Black Duck team from Synopsys has been involved with SPDX since its inception, and I had the pleasure of coordinating the activities of the project’s leadership for more than a decade. In addition, representatives from scores of companies have contributed to the important work of developing a standard way of describing and communicating the content of a software package.
Phil Odence, General Manager, Black Duck Audits, Synopsys
With the rapidly increasing interest in the types of supply chain risk that a Software Bill of Materials helps address, SPDX is gaining broader attention and urgency. FossID (now part of Snyk) has been using SPDX from the start as part of both software component analysis and for open source license audits. Snyk is stepping up its involvement too, already contributing to efforts to expand the use cases for SPDX by building tools to test out the draft work on vulnerability profiles in SPDX v3.0.
Gareth Rushgrove, Vice President of Products, Snyk
For more information on OpenChain: https://www.openchainproject.org/
For more information on SPDX: https://spdx.dev/
- Section 3.1.1 “Bill of Materials” in https://github.com/OpenChain-Project/Specification/raw/master/Official/en/2.1/openchainspec-2.1.pdf
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