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Software supply chain attacks aren’t theoretical anymore–they’re operational risks.

 Because organizations rely on open source and third-party components, maintaining 

 is a fundamental security requirement. But how do you secure the thousands of external components flowing into your development environment every day?

That’s exactly why the Secure Supply Chain Consumption Framework (

 provides a practical, principles‑driven approach to strengthening trust specifically for the 

 of open source software (OSS). Unlike other frameworks that focus on how you 

, explain how they work together, and show how they help organizations consume open source software with confidence.

 Before diving in, we recommend reading our previous post in the series:

Understanding S2C2F: How It Strengthens OSS Security

software supply chain integrity framework

 designed to reduce the risk of consuming malicious or vulnerable open source components. Originally developed by Microsoft and contributed to the OpenSSF, it shifts the focus from "secure coding" to "secure consumption."

The framework is built on a maturity model that helps organizations move from ad-hoc ingestion to a fully governed, secure supply chain.

Why S2C2F matters for supply chain integrity

Instead of vague promises about "security," S2C2F defines clear expectations for how external code enters your ecosystem. The S2C2F security principles focus on:

Reducing the attack surface of external dependencies.

Improving inventory visibility (knowing what you have).

decreasing mean-time-to-remediate (MTTR) when vulnerabilities are found.

The S2C2F framework is organized into eight distinct areas of practice. Individually, they address specific consumption risks; collectively, they create a "defense in depth" strategy for your 

The first and most critical practice is defining 

 open source packages enter your organization. Instead of allowing developers to pull directly from public registries (like npm or PyPI), which exposes you to 

 and "dependency confusion" attacks, S2C2F mandates using a central artifact repository.

 Centralize and cache all external dependencies.

Prevents "left-pad" incidents (deleted packages) and establishes a single control point for policy enforcement.

 This practice focuses on maintaining a complete, accurate record of all third-party artifacts used across your organization. This goes beyond a simple list; it requires generating and managing a 

When the next Log4j happens, you can instantly query 

 they are used. S2C2F emphasizes scanning not just for known vulnerabilities (CVEs), but also for malware, license compliance, and heuristic risk signals.

 Stop bad packages before they reach the build server.

 Reduces technical debt by blocking high-risk components early in the lifecycle.

 Software rot is a security risk. This practice ensures that your organization has a process for keeping dependencies up to date. Outdated packages are the number one vector for exploitation.

 Automate dependency updates (e.g., via bot PRs).

Minimizes the "vulnerability window" that attackers can exploit.

Explicitly define trust boundaries . The "Enforce" practice involves setting policies that automatically reject components that don't meet your security standards (e.g., blocking packages with critical CVEs or unacceptable licenses).

Automated policy gates at the ingestion point.

 Prevents human error and ensures compliance with supply chain integrity principles.

 Every action in the supply chain–from ingestion to deployment–should be logged. This practice ensures that you can trace exactly who brought a package in, when it was scanned, and where it was used.

Enables forensic investigation and proves compliance to auditors.

 For organizations with high security requirements , trusting the binary isn't enough. This practice involves rebuilding open source packages from the source code on your own trusted infrastructure to verify that the distributed binary matches the source code.

Verify artifact integrity independent of the upstream publisher.

Mitigates sophisticated attacks where the upstream build system is compromised (like SolarWinds).

 Security is a community effort. This practice encourages organizations to fix vulnerabilities they find in open source projects and, critically, contribute those fixes back to the upstream community.

 Strengthens the entire open source security framework and reduces the maintenance burden of carrying private patches.

Taken together, these eight practices provide a structured way to understand, assess, and control risk in complex, dependency‑driven ecosystems.

For organizations that rely heavily on open source, the 

 (Yes, because we have Audit logs and Update paths.)

By addressing these questions directly, S2C2F becomes a practical 

 model, moving you from reactive patching to proactive governance. Using an artifact manager to apply and enforce these practices allows organizations to automate and incorporate security into development pipelines without creating extra work for developers. 

Secure Supply Chain Consumption Framework (S2C2F) is a security framework adopted by the OpenSSF that focuses on securing how organizations consume (ingest) open source software. It outlines eight core practices and four maturity levels to improve supply chain integrity.

2. What is the difference between S2C2F and SLSA?

S2C2F is for consumers (focusing on ingestion, scanning, and inventory of dependencies), while SLSA is for producers (focusing on the build integrity and provenance of the artifacts you create). They are complementary frameworks.

3. Why are S2C2F practices important for open source security?

Because most modern applications are 80-90% open source code, the supply chain is the largest attack surface. S2C2F provides a standardized way to vet and manage this code, preventing attacks like dependency confusion and malicious injection.

Understanding the practices is only one step toward stronger supply chain integrity. Now, it's time to assess your maturity.

Software Supply Chain and Artifact Management Maturity Assessment

 Check if your developers are pulling directly from public repositories, like npm and Maven, or using a secure proxy.

 automates the Ingest, Scan, and Enforce pillars of S2C2F today.

Parul Jhawar

Marketing

Security Maturity Assessment Guide

The 8 core principles of S2C2F

 continue to rise, and organizations are under intense pressure to build trust in both the code they create and the open-source software (OSS) they consume.

To address this growing challenge, many teams are turning to the 

Secure Supply Chain Consumption Framework (S2C2F)

 designed to strengthen how organizations ingest, validate, and govern open-source components.

This blog is the second part of our Supply Chain Integrity Series. If you haven’t read the first article yet, check out:

Secure Supply Chain Consumption Framework

. It is a security model created to help organizations safely adopt open-source software by improving 

, integrity, and governance across the entire consumption lifecycle.

 side, how teams ingest, validate, scan, store, and trust OSS before it becomes part of their build pipeline.

 development lifecycle, S2C2F gives teams a clear, maturity-based path to reduce 

Why S2C2F matters for open source security?

Modern software is overwhelmingly built on open source. However, the speed and flexibility of OSS come with significant risks. Without a framework like S2C2F, teams are vulnerable to:

S2C2F helps teams systematically reduce these risks by defining the controls required at each maturity level, starting with simple ingestion hygiene and moving all the way to full hermetic, zero-trust infrastructure. It supports 

How S2C2F works: A maturity-based path to integrity

The framework defines four maturity levels. You don’t need to jump to Level 4 immediately; 

 is designed to support incremental adoption as your organization grows.

Level 1: Ingestion control (The Baseline)

 Stop pulling directly from public registries.

 Protection against removal events, registry outages, and basic dependency integrity issues. You also gain a foundational inventory of all OSS components.

Level 2: Secure consumption & faster MTTR

 Prevent packages with known vulnerabilities from entering the build loop and eliminate manual CVE checking.

Audit that consumption is through the approved ingestion method.

Level 3: Malware defense & Zero-day detection

 Defend against malicious actors and typo-squatting.

 becomes proactive. You are protected from dependency confusion and advanced attacks.

Proactive reviews for yet-undiscovered vulnerabilities.

Verify that binaries match the trusted source code.

 Total independence and hermetic security.

 Maximum integrity–even from compromised public upstreams.

How Cloudsmith helps you achieve supply chain integrity

Implementing S2C2F manually is a significant operational challenge. 

 designed specifically to automate software supply chain integrity.

Our platform aligns with S2C2F principles, allowing you to move from Maturity Level 1 to Level 3 almost immediately.

Cloudsmith doesn’t just support S2C2F; it accelerates it, turning 

Software supply chain best practices inspired by S2C2F

To secure the open-source consumption lifecycle, teams should adopt these 

Enforce automated vulnerability and malware scanning

 rather than pulling directly from the wild.

 to ensure code comes from where it claims to.

Rebuild sensitive or high-risk dependencies

S2C2F offers a clear, practical roadmap for improving 

, and strengthening integrity, without overwhelming your team with complex controls from day one.

Whether you're starting at Level 1 or aiming for Level 4, frameworks like S2C2F help organizations adopt open source more safely and confidently.

1. How does S2C2F improve software security?

By enforcing ingestion hygiene, vulnerability scanning, malware defense, and provenance validation, S2C2F reduces the entry points attackers use to infiltrate supply chains.

2. Why does S2C2F matter for open source?

Most software today is open source. S2C2F provides a structured way to safely consume OSS at scale, lowering dependency risks without slowing development.

3. What are the S2C2F steps for securing OSS projects?

Ingest securely → Validate → Scan → Enforce → Audit → Rebuild (when needed).

4. Which frameworks secure software supply chains?

, NIST SSDF, SLSA, CIS guidelines, and SPDX/OSV for standardization.

5. How do you reduce OSS supply chain risk?

You can reduce risk by using private registries, validating provenance, enforcing policies, keeping SBOMs, and scanning for malware and vulnerabilities proactively.

6. What are the guidelines for secure OSS consumption?

Consume through a private proxy, validate integrity, scan frequently, enforce policies, and maintain SBOMs for transparency.

Understanding S2C2F: How it strengthens OSS security

Software today is built on an ever-expanding mesh of open-source components, third-party libraries, container images, package registries, automated systems, and build services. While this ecosystem accelerates development, it introduces a terrifying reality: a single compromised dependency or an unexpected upstream change can ripple through your entire product stack in minutes.

It has become one of the most critical pillars of modern DevSecOps. When your dependencies are trustworthy, verifiable, and governed correctly, you reduce the risk of malware insertion, dependency confusion, tampering, or upstream failure. Without this foundation, even the strongest supply chain security controls at the application layer won’t matter.

This blog, the first in Cloudsmith’s new series on 

, breaks down what software supply chain integrity actually means, why maintaining it is so challenging, and how frameworks like 

S2C2F (Secure Supply Chain Consumption Framework)

 help organisations implement consistent, secure open-source consumption practices.

Ready to understand where your supply chain security stands? Take our 

Software Supply Chain Maturity Assessment

 refers to the ability to ensure that every component in your software, from source code to dependencies to build artifacts and containers, remains authentic, untampered, verified, and sourced from trusted origins.

Do we fully trust the software we’re using?

Are we confident it hasn’t been altered, compromised, or replaced?

It goes beyond traditional application security. While AppSec focuses on your code, integrity focuses on the 

Where did this software originate? Can we verify the source?

Was it built by who it claims to be built by?

Has anything been modified, injected, or tampered with?

How do we enforce policies around what can (and cannot) enter our supply chain?

Can we rely on the upstream source, or do we have a trustworthy internal copy?

As organizations scale, maintaining this integrity moves from "nice to have" to "mission-critical."

Why supply chain integrity is challenging today?

Modern engineering teams consume thousands of open-source packages and containers from public ecosystems like npm, PyPi, Maven, and Docker Hub. These communities evolve fast, and threat actors have learned to weaponize that speed.

The "trust but verify" model is dead. We are now in a "verify, then trust" era. Here is why the landscape has shifted:

1. Malicious package uploads / Typosquatting

Attackers publish packages with names similar to legitimate ones (e.g., reqeust instead of request) to trick developers or automated tools into installing them. Once installed, these packages often run "post-install" scripts that exfiltrate environment variables or keys.

If you use an internal package name (e.g., my-company-auth) that isn't registered publicly, attackers can register that name on a public registry with a higher version number. By default, many package managers will pull the "latest" version -tricking your build system into downloading the attacker's public malware instead of your private code.

If an open-source maintainer’s credentials are stolen, attackers can modify widely-used packages, injecting backdoors, data exfiltration, or crypto-mining code into thousands of downstream applications instantly.

4. Upstream removal or "Left-Pad" incidents

It’s not always malice; sometimes it’s chaos. A popular OSS package can be unpublished by its author (like the infamous left-pad incident), breaking builds across the globe. If you rely on public registries directly, your pipeline is at the mercy of their uptime.

Malware embedded inside base images, compressed binary artifacts, or build scripts can spread downstream silently and undetected.

This modern threat landscape requires a shift in thinking. It’s not just about using open source securely; it’s about maintaining centralized ingestion, policy enforcement, provenance checks, and continuous monitoring

The pillars of software supply chain integrity

To help teams build strong governance around software dependencies, several core integrity principles have emerged. These align closely with industry standards, such as SLSA (Supply Chain Levels for Software Artifacts) and S2C2F.

Software supply chain integrity relies on a set of proven pillars that help teams control how software is sourced, validated, stored, and consumed. These include:

Never pull directly from the public internet in production builds. Consume OSS and third-party software through a centralized "front door", an artifact repository controlled by your organization. This acts as a firewall for your code, preventing accidental consumption of malicious packages and shielding you from upstream outages.

You cannot secure what you cannot see. A Software Bill of Materials (SBOM) provides a clear inventory of all dependencies, versions, and transitive packages. It's critical for identifying risky components and responding quickly to new vulnerabilities.

Automate detection at the gate. Scanning must happen 

 a package enters your environment. This includes checking for:

Known CVEs (Common Vulnerabilities and Exposures)

 standards. Establish global rules for approved packages, permitted licenses, vulnerability thresholds, and immutability. Governance ensures that developers in Team A and Team B are subject to the same safety standards and regulations.

Verify the origin. Ensuring your binaries match their source code is essential. Provenance checks confirm who built the software, where it was built, what tools were used, and whether the artifact signature matches the builder's key.

To achieve maximal integrity, organizations rebuild OSS packages inside their own trusted environment, signing them and generating SBOMs for each build.

Introducing S2C2F: A framework for supply chain integrity

One of the most practical and widely adopted frameworks for implementing software supply chain integrity is the Secure Supply Chain Consumption Framework (S2C2F).

Originally created by Microsoft in 2019 to secure their massive internal development loops, it was donated to the Open Source Security Foundation (OpenSSF) in 2022. It now serves as the industry standard for how organizations should 

 open-source software (as opposed to SLSA, which focuses on how you 

S2C2F offers eight core principles and four maturity levels to help organizations enhance their approach to consuming open-source software.

 All external artifacts must come through a central, controlled location.

 You must maintain a complete list of all OSS components you use.

 Vulnerabilities must be patched within a defined SLA.

 Developers must be prevented from bypassing secure methods technically.

 You must log and audit all ingestion sources and changes that occur.

 Automated scanning for CVEs and malware is mandatory.

 For high security, rebuild OSS on a trusted infrastructure.

 If a patch isn't available, fork and fix it yourself temporarily.

To keep this focused, we’ll dive deeper into S2C2F, including maturity levels and practical implementation steps, in Part 2 of this series.

1. What is software supply chain integrity?

Software supply chain integrity is the practice of ensuring that every component in your software development lifecycle—dependencies, containers, build artifacts, and scripts—is authentic, verified, tamper-free, and sourced from trusted origins. It answers the question: "Is this code exactly what it claims to be?"

2. Why is software supply chain integrity important?

Modern software relies heavily on third-party and open-source components that can be compromised, removed, or tampered with. Integrity prevents attacks such as dependency confusion, malware injection, and supply chain compromise.

3. What is the difference between SLSA and S2C2F? 

Think of them as two sides of the same coin. SLSA (Supply-chain Levels for Software Artifacts) focuses on securing the 

 process (how you create software). S2C2F (Secure Supply Chain Consumption Framework) focuses on the 

 process (how you consume open-source software). You need both for a complete software supply chain security strategy.

4. How does Cloudsmith prevent dependency confusion attacks?

The most effective way is to use a private artifact repository (like Cloudsmith) that supports "upstream proxying" with namespace protection. This ensures that if an internal package name exists, the build system will never look for it on the public registry, preventing the injection of malicious public packages.

5. How does Cloudsmith support supply chain integrity?

Cloudsmith acts as a secure "supply chain firewall." It allows organizations to centralize OSS ingestion, automatically scan for malware and vulnerabilities, manage SBOMs, enforce license policies, and verify provenance—automating the requirements of frameworks like S2C2F.

What is Software Supply Chain Integrity?

By now it’s clear the use of GenAI tooling like Cursor and Claude has fundamentally changed how code is written. This shift, which we explored in depth in our previous post, moves the security perimeter beyond just the generated code. Today, every engineering team building an AI-native application must equally prioritise securing the AI models and LLMs they pull into their tech stack. This forces us to rethink supply chain security for the AI era.

This post will dive deep into a concrete solution: leveraging Cloudsmith's Enterprise Policy Manager (

) to enforce rigorous security and governance policies on LLMs and datasets sourced from the 

Effective governance hinges on detailed metadata. Cloudsmith addresses this by providing a customised data model specifically for Hugging Face models and datasets. This is the crucial enabler, allowing developers and SecOps teams to write granular policies in 

 that target attributes unique to this package type.

The following examples showcase how EPM policies can be constructed to tackle common, yet critical, supply chain risks associated with adopting LLMs.


Whitelisting trusted publishers to enforce provenance

For mature organisations, time-to-market often depends on leveraging high-quality, pre-vetted artifacts from established entities like 

. Instead of subjecting these known-good sources to redundant policy checks, you can use an EPM policy to create a allowlist.

Create a terminal policy with the highest precedence (

If the model's publisher is on the approved list, the policy immediately sets the package state to '

. All subsequent policies are bypassed, dramatically streamlining ingestion for high-confidence artifacts.

 policy primarily targets packages pulled via a Hugging Face upstream and ignores packages that are pushed directly into Cloudsmith. This ensures reliable traceability, as packages pushed directly to Cloudsmith lack the verified publisher metadata from the Hub.

Blocking Models with Unsafe Files via Security Scans

The concept of a security vulnerability extends beyond traditional CVEs when dealing with LLMs. Models can contain malicious code or file formats. Hugging Face Hub has mitigated this by providing 

Cloudsmith captures this crucial upstream security data and exposes it to EPM. This allows you to write a policy that enforces a zero-tolerance stance on models flagged as unsafe by any of the integrated scanners.

After the policy has been created, associate an 

If a package matches the policy, you can use the decision logs to view the detailed results of the security scan for the package. The 

Cloudsmith Blog

The 8 core principles of S2C2F

Understanding S2C2F: How it strengthens OSS security

What is Software Supply Chain Integrity?

Extend EPM policies to Hugging Face artifacts

Slopsquatting and Typosquatting: How to Detect AI-Hallucinated Malicious Packages

The DevOps Guide to Mitigating Software Supply Chain Risks

Shai-Hulud: The Second Coming - What You Need to Know and Do Now

Securing the intersection of AI models and software supply chains

Breaking the "Department of No": Ship fast but also secure

AI generated code is changing the demands being put on artifact management

npm ecosystem alert: What you need to do today with Cloudsmith

NX npm Supply Chain Attack: How Cloudsmith Would Have Contained the Blast Radius