Software bill of materials: What it is and why you need one

Today’s applications are built on a complex web of third-party components, open-source libraries, and even AI-generated code. While these external resources can drastically accelerate development, they also introduce significant risks. Security vulnerabilities, licensing issues, and outdated dependencies can all pose serious threats to the integrity of your software. This is where a software bill of materials (SBOM) comes into play.

An SBOM is essentially an inventory list that details all the components, libraries, and dependencies used in your software. Just as a recipe lists the ingredients needed to make a favorite meal, an SBOM helps developers track and manage the various pieces that make up their applications.

Using a software bill of materials (SBOM) is a highly effective strategy for reducing software supply chain vulnerabilities, staying compliant with major data privacy regulations, and keeping the components of a software app transparent and trackable.

In this post, we’ll explore what an SBOM is, why it’s important in modern software development, and how it can help you safeguard your software from potential vulnerabilities and compliance issues.

What is the software supply chain?

Most organizations that develop software — from small startups to large enterprises — rely on third-party libraries and tools to build their applications. The combination of these libraries, tools, and other components that are integrated into an application is known as the software supply chain.

A software supply chain for a typical web application might include the following components:

• A running Linux instance
• System-wide shared libraries like libcrypt and glibc
• Open source frameworks and libraries installed via package repositories like npm, NuGet, and Maven
• Chunks of source code copied from other applications or resources like Stack Overflow
• Code generated by AI coding assistants
• Supporting applications like databases and in-memory caches
• JavaScript libraries like jQuery, D3, and React
• Underlying supporting services such as Apache, IIS, and nginx

If any of these components contain a security vulnerability, it can affect all applications that depend on the compromised component, putting sensitive data at risk. Threat actors often exploit these supply chain vulnerabilities to breach target networks.

One way to reduce software supply chain vulnerabilities is to maintain a SBOM that provides a detailed inventory of all components used in an application.

Protecting the software supply chain with SBOMs

In recent years, the growing complexity of software systems and the increasing reliance on third-party components have exposed critical vulnerabilities within the software supply chain. High-profile security breaches have highlighted the risks associated with these dependencies, prompting governments and organizations alike to take decisive action.

Recognizing the urgent need for enhanced security, the U.S. government issued an executive order in 2021 mandating federal agencies to improve software supply chain security. A key component of this initiative is the requirement to provide an SBOM for each product, either directly to purchasers or via a public website.

The National Telecommunications and Information Administration (NTIA) suggests three formats for generating the SBOM inventory list that identifies software entities and their associated metadata:

• The Software Package Data Exchange (SPDX) is an open standard for creating an SBOM inventory list. The list includes all software components, component licenses, copyrights, and security references.
• The OWASP CycloneDX is a lightweight SBOM standard designed for risk analysis. CycloneDX creates a complete inventory of first- and third-party software components. It can document component types including applications, containers, libraries, files, firmware, frameworks, and operating systems.
• The International Organization for Standardization (ISO) and the International Electrotechnical Commission (IEC) developed the Standard for software identification (SWID). SWID is an XML file containing a list of software components and their licenses, patch statuses, and installation bundles.

Why the SBOM is important

The software supply chain has become a leading source of software vulnerabilities and breaches. Every tool, framework, or library used to write, build, or run applications can be exploited.

Cataloging the components used to create each application enables organizations to detect and resolve security vulnerabilities before malicious actors can gain unauthorized access to sensitive resources.

The use of SBOMs is also beneficial because it:

• Avoids reusing vulnerable components in software projects
• Helps discover vulnerable parts in current applications
• Better manages the software supply chain risk through knowledge of all components (and their dependencies) being used in software applications
• Helps organizations better comply with various data protection regulations by providing a list of all application components and their relevant characteristics
• Helps organizations select preferred software vendors who provide their applications’ SBOMs
• Helps organizations maintain an inventory of all software apps in their IT environment
• Conserves time and resources by detecting vulnerable parts in the early design phases of the software development life cycle (SDLC)
• Calls necessary attention to the security risks associated with the software supply chain

How to generate an SBOM

An organization or individual can generate an SBOM manually or with automated technology. The manual approach may be right for smaller projects, but it can be less desirable for others.

The manual method

Developers can manually list software components with each component’s version, license, dependencies, and any additional relevant information.

This method is suitable for small projects with few components. It is far from ideal for larger projects, though. According to ZDNet, most GitHub projects have around 700 dependencies.

Enterprise-level systems are sure to exceed this number. Attempting to manually generate an SBOM inventory for a project with thousands of direct and transitive dependencies is just not realistic.

The manual method is also prone to human error. It is all too easy to update a dependency and then forget to update the SBOM.

The automated method

For most projects, automating the SBOM is the best approach. Automation lets you maintain an updated list of all components, including languages, libraries, and Docker images.

You can incorporate automated tools into your continuous integration and continuous delivery (CI/CD) pipeline to scan all of your software projects and update their associated components as needed. Popular dependency scanners include Snyk and Anchore.

Most SBOM generation tools also integrate well with CI/CD tooling. These tools automatically scan your software projects, listing both proprietary and open-source software components and related attributes like licenses and dependencies on third-party libraries.

Summary

An SBOM offers many benefits for compliance, security, and managing the various components of each application’s license agreements. Automating this SBOM helps ensure complete coverage and current information for your organization.

Organizations that use SBOM and link their component inventory with cyber threat intelligence feeds can better track zero-day vulnerabilities in their applications. Then, they can fix them before incurring significant damage to their software integrity.

Learn more about how you can integrate dependency scans and SBOM generation tools in your CI/CD pipeline to strengthen your software security.