OpenSSF

Definition of OpenSSF and Its Role in Securing Open Source Software

OpenSSF (Open Source Security Foundation) is a collaborative initiative under the Linux Foundation that develops standards, tools, and best practices for securing open source software. Founded in 2020 from the merger of the Open Source Security Coalition and the Core Infrastructure Initiative, OpenSSF brings together technology companies, security engineers, and developers to address security gaps in open source components that form the foundation of modern software development.

OpenSSF is used by DevSecOps teams, security directors, and enterprise development organizations that need to evaluate, secure, and manage open source dependencies across their software supply chains. The foundation's primary projects include Scorecard (automated security health metrics), SLSA (supply chain integrity framework), Sigstore (free code signing infrastructure), and the GUAC project (graph-based dependency analysis). These tools help organizations reduce risk from the open source components that make up 70–90% of most modern applications.

Alternative names and related terms: Open Source Security Foundation, OpenSSF Alliance, Linux Foundation OpenSSF, OpenSSF Scorecard, OpenSSF Best Practices Badge.

The foundation operates under a neutral governance structure that allows competing organizations — including Google, Microsoft, Amazon, IBM, Intel, and others — to collaborate on shared security challenges. For security directors managing enterprise software supply chains, OpenSSF provides practical tools and frameworks that address vulnerabilities cascading through software supply chains, from small startups to Fortune 500 companies.

What Is OpenSSF and How Does It Work?

The Open Source Security Foundation functions as both a coordinating body and an active developer of security solutions for the open source ecosystem. Rather than publishing guidelines alone, OpenSSF creates practical tools, frameworks, and processes that development teams can implement directly into their workflows. This hands-on approach distinguishes it from purely advisory organizations and makes its work immediately actionable for teams managing complex software supply chains.

How Are OpenSSF Working Groups Organized?

OpenSSF organizes its efforts through 6 specialized working groups, each focused on a specific aspect of open source security:

1. Security Tooling: Develops and maintains open source security tools for CI/CD integration — vulnerability detection, dependency analysis, and security testing.
2. Security Best Practices: Creates guidance documents, training materials, and certification programs for implementing security throughout the software development lifecycle.
3. Identifying Security Threats: Monitors emerging threats to open source software and coordinates responses to critical vulnerabilities affecting widely-used projects.
4. Securing Critical Projects: Directs resources and expertise toward improving security of foundational open source projects that millions of applications depend on.
5. Supply Chain Integrity: Develops standards and tools for verifying authenticity and integrity of open source packages throughout the software supply chain.
6. Vulnerability Disclosures: Establishes processes and infrastructure for responsible disclosure and remediation of security vulnerabilities in open source projects.

Each working group meets regularly via video conference and accepts participation from organizations of all sizes and individuals with various skill sets.

What Are the Main Projects and Tools Developed by OpenSSF?

OpenSSF has launched several flagship projects that directly impact how organizations approach open source security. The following table summarizes the primary tools and their functions.

Scorecard evaluates open source projects against automated security checks, producing scores that indicate overall security health. Checks include whether projects require code review before merging, maintain security policies, use dependency update tools, and implement branch protection. Development teams use these scores to make informed decisions about which packages to trust.

SLSA defines a framework for progressively improving supply chain security across 4 levels. Level 1 requires basic provenance documentation. Level 2 adds hosted build platform requirements. Level 3 requires hardened build platforms. Level 4 requires hermetic, reproducible builds. Organizations can implement SLSA incrementally as their security maturity improves.

Sigstore provides free infrastructure for signing and verifying software artifacts. Cosign handles container signing, Rekor maintains transparency logs, and Fulcio issues certificates. Together, these components enable developers to sign releases and users to verify signatures without managing complex certificate infrastructure. Transparency logs make it difficult for adversaries to forge signatures without detection.

GUAC (Graph for Understanding Artifact Composition) is maintained by Kusari and aggregates software supply chain metadata — SBOMs, SLSA provenance, vulnerability data, and scorecard results — into a queryable graph database. This allows organizations to answer questions like "which of my applications are affected by this vulnerability?" or "what is the full dependency chain for this component?" across their entire portfolio.

How Does OpenSSF Impact Software Supply Chain Security?

Software supply chain security has moved from a niche concern to a board-level priority. Open source components in applications come with inherent risks — each dependency represents attack surface that adversaries may exploit. OpenSSF addresses these risks through multiple complementary approaches.

How Does OpenSSF Address Dependency Vulnerabilities?

Modern applications typically include 200–2,000+ open source dependencies, creating a complex web of transitive relationships that few teams fully understand. OpenSSF's automated security tooling helps teams gain visibility into dependency trees and identify components with known vulnerabilities or concerning security practices.

The foundation promotes Software Bills of Materials (SBOMs) as standardized inventories of software components. When new vulnerabilities emerge, organizations with accurate SBOMs can determine within hours whether their applications are affected, rather than spending days or weeks on manual analysis. This capability proved critical during the Log4Shell vulnerability (CVE-2021-44228), where organizations needed to rapidly identify affected systems across their entire infrastructure.

OpenSSF supports both SPDX and CycloneDX SBOM formats, recognizing that different use cases and regulatory requirements may favor different formats. This flexibility avoids vendor lock-in to a specific toolchain.

How Does OpenSSF Improve Security Practices Across Open Source Projects?

Many open source projects lack dedicated security expertise or resources. The median critical open source project has 2–5 active maintainers, despite being used by thousands of commercial applications. OpenSSF provides security training, documentation, and direct support to help maintainers implement better security practices.

The Best Practices Badge program incentivizes projects to adopt security controls by publicly recognizing those that meet defined criteria. This approach benefits the entire ecosystem because improvements to widely-used dependencies cascade to all applications that rely on them. When a critical library implements better security practices, thousands of downstream applications become more secure without individual intervention.

How Does OpenSSF Build Trust Through Verification?

Trust represents a fundamental challenge in open source software consumption. How can teams verify that a downloaded package actually comes from the claimed author and hasn't been tampered with during distribution?

OpenSSF addresses this through:

• Cryptographic signing (Sigstore): Enables developers to sign releases and users to verify signatures using free, transparent infrastructure
• Transparency logs (Rekor): Provides public records of signing events, making signature forgery detectable
• Reproducible builds: Allows anyone to verify that published binaries correspond to their claimed source code
• Provenance tracking (SLSA): Documents how, where, and by whom software artifacts were built

These capabilities become increasingly important as supply chain attacks grow more sophisticated, with adversaries compromising package repositories, build systems, and distribution infrastructure.

5 Steps to Implement OpenSSF Standards in Your Organization

For security directors and DevSecOps leaders looking to strengthen software supply chain security, implementing OpenSSF standards offers a practical starting point grounded in industry consensus.

Step 1: Assess your current software supply chain security posture. Evaluate 5 key dimensions before implementing new tools:

• Dependency management: Do you track all open source dependencies including transitive dependencies? Do you maintain accurate inventories across applications?
• Vulnerability response: What is your mean time to remediate critical vulnerabilities in dependencies? Can you respond within 24–72 hours when critical issues emerge?
• Build and release security: Do your build pipelines produce artifacts that accurately reflect source code? What controls prevent unauthorized modifications?
• Verification and signing: Do you verify the authenticity of dependencies before incorporating them? Do you sign your own releases?
• Security training: Are developers equipped to make secure decisions about dependency selection and usage?

Step 2: Adopt Scorecard for dependency visibility. Integrate OpenSSF Scorecard into your dependency review process. This provides immediate visibility into the security health of your dependencies and helps teams make informed decisions about which packages to trust. Scorecard can be integrated into pull request automation to provide feedback when developers propose adding new dependencies.

Step 3: Implement SLSA incrementally. Start with SLSA Level 1 (basic provenance documentation about build processes). Progress to Level 2 (hosted build platforms) and Level 3 (hardened builds) as maturity increases. Each level provides stronger guarantees about artifact integrity without requiring wholesale changes.

Step 4: Enable code signing with Sigstore. Integrate Sigstore to both verify signatures of incoming dependencies and sign your own releases. The free infrastructure eliminates the need to manage your own certificate authorities, reducing implementation friction. No cost for the signing infrastructure itself.

Step 5: Establish governance, metrics, and continuous improvement. Create a Software Security Committee with representatives from development, security, and operations. Define policies for acceptable dependency risk levels, security review criteria, and vulnerability response procedures. Track metrics including:

• Percentage of dependencies with known high-severity vulnerabilities
• Mean time to remediate vulnerabilities after disclosure
• SBOM coverage across your application portfolio
• Percentage of builds meeting SLSA compliance levels
• Adoption of signed artifacts across internal and external releases

How Does OpenSSF Relate to Regulatory Compliance?

Government agencies and regulatory bodies have increasingly focused on software supply chain security. OpenSSF standards and tools align directly with these regulatory requirements, providing practical implementation paths for compliance.

Which Regulations Does OpenSSF Help Address?

Organizations that adopt OpenSSF frameworks often find they've addressed many regulatory requirements as a side effect of improving their actual security posture. The foundation actively engages with policy makers to ensure that regulations promote effective security practices rather than creating compliance overhead without corresponding security benefits.

How Does OpenSSF Support SBOM Requirements?

Many emerging regulations require software vendors to provide machine-readable SBOMs to their customers. OpenSSF tools help organizations generate accurate, comprehensive SBOMs as part of their build processes. Automating SBOM generation ensures accuracy and reduces manual effort as applications evolve.

The foundation supports both SPDX and CycloneDX SBOM formats. This flexibility allows organizations to adopt SBOM practices without being locked into a specific format that might not meet future requirements.

How Does OpenSSF Enable Secure Development Attestations?

Some regulatory frameworks require software vendors to attest that they follow secure development practices. OpenSSF's Best Practices Badge program provides a framework for demonstrating compliance with security development standards. Organizations that achieve badge certification can point to specific, verified practices when responding to customer security questionnaires or regulatory inquiries.

The foundation's work on attestation formats and verification infrastructure enables automated verification of security claims. Rather than relying solely on vendor assertions, customers can verify cryptographic attestations about how software was built, what security tools were run, and what dependencies were included.

What Is the Relationship Between OpenSSF and the Linux Foundation?

OpenSSF operates as a project under the Linux Foundation, benefiting from the Linux Foundation's neutral governance structure, legal framework, and administrative infrastructure. This relationship provides organizational stability and credibility while allowing OpenSSF to maintain focus on its security mission rather than operational overhead.

The Linux Foundation's neutral umbrella proves particularly valuable for security initiatives where competitors must collaborate on shared challenges. Technology companies that compete in the marketplace can collaborate on OpenSSF projects without concerns about any single vendor controlling the direction or benefiting disproportionately.

OpenSSF's governance structure includes representatives from member organizations across the technology industry. Member companies include Google, Microsoft, Amazon, IBM, Intel, GitHub, Red Hat, VMware, JPMorgan Chase, and others. This multi-stakeholder approach ensures OpenSSF's work addresses real challenges faced by different types of organizations.

OpenSSF Tools Compared to Commercial Alternatives

When evaluating open source security tooling, organizations often compare OpenSSF projects to commercial alternatives. The following table provides a practical comparison.

Key takeaway: OpenSSF tools are most valuable as foundational standards and free infrastructure that organizations build upon. Most enterprise teams use OpenSSF standards (SLSA, SBOM formats, Scorecard checks) alongside commercial tools that provide managed infrastructure, support, and deeper analysis. The two approaches are complementary rather than competitive.

When OpenSSF May Not Be Sufficient: Limitations and Edge Cases

OpenSSF tools and standards provide significant value but have limitations that organizations should understand before relying on them as their sole security strategy.

Scorecard provides security health indicators, not guarantees. A high Scorecard score means a project follows good security practices. It does not mean the project is free of vulnerabilities. Projects with perfect scores can still contain undiscovered security flaws. Scorecard should be one input to dependency decisions, not the only one.

SLSA compliance does not prevent all supply chain attacks. SLSA protects against specific attack vectors like build tampering and provenance forgery. It does not protect against vulnerabilities in source code, compromised developer accounts that commit malicious code through legitimate channels, or social engineering attacks against maintainers. SLSA Level 4 (hermetic, reproducible builds) remains difficult to achieve for most organizations.

OpenSSF tools require integration effort. The foundation provides tools and standards, not turnkey solutions. Organizations must invest engineering time to integrate Scorecard checks into CI/CD pipelines, implement SLSA provenance generation, configure Sigstore signing, and deploy GUAC for metadata aggregation. Teams with fewer than 5 dedicated security engineers may find this integration effort challenging without commercial tooling support.

Community-maintained projects have variable response times. OpenSSF projects are developed by volunteers and sponsored contributors. Bug fixes, feature requests, and security patches may take longer than commercial products with SLA commitments. Organizations requiring guaranteed response times should evaluate commercial alternatives or supplement OpenSSF tools with paid support options.

Not all open source ecosystems are equally supported. Scorecard and other OpenSSF tools work best with GitHub-hosted projects. Projects hosted on GitLab, Bitbucket, or self-hosted repositories may have limited Scorecard coverage. Language ecosystem support varies — npm, PyPI, and Go modules have stronger tooling than some other package managers.

Regulatory compliance may require additional documentation. While OpenSSF tools align with regulatory requirements, they do not automatically generate the compliance documentation, audit trails, or executive reporting that regulated industries require. Organizations in healthcare (HITRUST, HIPAA), financial services (PCI DSS, SOX), or government (FedRAMP) may need commercial compliance platforms alongside OpenSSF tools.

How Can Development Teams Get Involved with OpenSSF?

Development teams can participate in OpenSSF through several practical entry points:

1. Join working group meetings. Working groups meet regularly via video conference and welcome new participants. Meetings are open to organizations of all sizes.
2. Contribute to OpenSSF projects. Follow standard open source contribution models — submit bug reports, propose features, contribute code, or improve documentation. Many projects label "good first issues" for newcomers.
3. Implement OpenSSF tools and share feedback. Real-world usage reveals limitations not apparent during development. Teams that report their implementation experiences help improve tools for the entire community.
4. Become a member organization. Formal membership provides governance participation, visibility in OpenSSF communications, and influence over strategic direction. Membership tiers accommodate organizations of various sizes and resource levels.

Frequently Asked Questions About OpenSSF

What is the OpenSSF?

OpenSSF (Open Source Security Foundation) is an organization under the Linux Foundation that develops standards, tools, and best practices and advocates policies for securing open source software. Founded in 2020, it brings together technology companies including Google, Microsoft, Amazon, and IBM to address security gaps in open source components used by the majority of modern software applications.

What is the difference between OpenSSF Scorecard and SLSA?

‍Scorecard evaluates the security health of open source projects by checking practices like code review requirements, branch protection, and dependency management. SLSA is a framework for ensuring the integrity of software artifacts through the build and distribution process. Scorecard helps you decide whether to trust a dependency. SLSA helps you verify that the dependency you received is the one the maintainer intended to publish. They address different aspects of supply chain security and are designed to be used together.

Is OpenSSF free to use?

‍Yes. All OpenSSF tools, frameworks, and standards are free and open source. Sigstore provides free code signing infrastructure. Scorecard is free to run against any GitHub-hosted project. SLSA is a free framework with no licensing costs. Organizations can implement these tools without paying licensing fees, though integration and maintenance require engineering time.

How does OpenSSF relate to GUAC?

‍GUAC (Graph for Understanding Artifact Composition) is an OpenSSF project maintained by Kusari. GUAC aggregates software supply chain metadata — SBOMs, SLSA provenance, vulnerability data, and Scorecard results — into a queryable graph database. This allows organizations to understand relationships between components, vulnerabilities, and attestations across their entire software portfolio rather than analyzing each artifact in isolation.

What is the OpenSSF Best Practices Badge?

‍The Best Practices Badge is a certification program where open source projects can self-certify that they follow security and development best practices. The badge evaluates criteria including vulnerability response processes, cryptographic signing, security testing, and documentation. Projects that meet all criteria receive a publicly displayed badge. The program has three levels: passing, silver, and gold.

Does OpenSSF replace commercial security tools?

‍No. OpenSSF provides foundational standards and free infrastructure that most enterprise teams use alongside commercial tools. OpenSSF defines what to measure (Scorecard), how to verify (SLSA, Sigstore), and what formats to use (SPDX, CycloneDX). Commercial tools like the Kusari Platform, Snyk, Anchore, and FOSSA provide managed infrastructure, enterprise support, deeper analysis, and compliance reporting. The two approaches are complementary.

How does OpenSSF help with regulatory compliance?

‍OpenSSF tools align with requirements from US Executive Order 14028, EU Cyber Resilience Act, FDA Section 524B, NIST SSDF, and PCI DSS v4.0. Specifically, OpenSSF SBOM tooling helps meet software composition transparency requirements. SLSA helps meet integrity verification requirements. The Best Practices Badge helps demonstrate secure development attestations. However, OpenSSF tools alone may not generate all compliance documentation regulated industries require.

Which companies are members of OpenSSF?

‍OpenSSF members include Google, Microsoft, Amazon, IBM, Intel, GitHub, Red Hat, VMware, JPMorgan Chase, Morgan Stanley, Kusari, Chainguard, and others. The foundation operates under the Linux Foundation and accepts members at multiple tiers to accommodate organizations of different sizes. Member companies contribute financial resources, engineering time, and expertise to OpenSSF initiatives.

How long does it take to implement OpenSSF standards?

‍Implementation timelines vary by tool and organizational maturity. Integrating Scorecard into CI/CD pipelines typically takes 1–2 weeks. Achieving SLSA Level 1 takes 2–4 weeks for teams with existing CI/CD infrastructure. Sigstore integration takes 1–3 weeks. Full SLSA Level 3 compliance may take 3–6 months depending on build system complexity. Organizations starting from scratch with limited security automation should expect longer timelines.

What is the OpenSSF Alpha-Omega Initiative?

‍Alpha-Omega directs funding and security expertise to improve the security of critical open source projects. The "Alpha" component works with maintainers of the most critical projects to implement security improvements. The "Omega" component uses automated security analysis to find and fix vulnerabilities across a broader set of open source projects. The initiative is funded by OpenSSF member organizations and has provided support to projects including Node.js, jQuery, and Python.

Strengthening Your Software Supply Chain with OpenSSF

The software supply chain security challenges organizations face require collective action and shared solutions. OpenSSF provides frameworks, tools, and best practices that development teams can implement to reduce risks from open source dependencies. From vulnerability management and dependency tracking to cryptographic signing and build security, the foundation's work addresses the full spectrum of supply chain security concerns.

For DevSecOps leaders and security directors managing complex application portfolios, OpenSSF offers practical paths forward grounded in industry consensus. Teams can begin by integrating individual tools like Scorecard or implementing SBOM generation. These incremental improvements build toward comprehensive supply chain security over time, allowing organizations to improve their posture while maintaining development velocity.

The economic model OpenSSF enables — where organizations pool resources to improve shared infrastructure — creates security benefits that individual organizations could not achieve independently. By contributing to critical open source projects and developing shared tools, member organizations strengthen the foundation that all software builds upon.

As regulations around software supply chain security continue to evolve, organizations that have adopted OpenSSF frameworks will be well-positioned for compliance. The foundation actively engages with policy makers to ensure regulations promote effective security practices, and its tools provide practical implementation paths for meeting regulatory requirements.

Kusari is a creator and maintainer of the OpenSSF GUAC project and holds positions of influence in the open source software community. To see how the Kusari Platform helps organizations implement OpenSSF best practices — including SBOM lifecycle management, dependency graph analysis, and policy enforcement — request a demo.