Software Supply Chain Security: Risks and Best Practices

Securing the Software Supply Chain: Key Risks, Threats, and Prevention

Modern software is built on layers you don’t fully control like open-source libraries, third-party pipelines, and external registries. By the time malicious code reaches users, it looks completely legitimate. That’s the software supply chain problem. This article breaks down what it is, where it fails, and how to secure it.

What is a Software Supply Chain?

A software supply chain is every tool, system, person, and process involved in building and delivering software right from the first line of code to the end user’s device. It’s not just the code but everything the code touches.

This goes beyond the traditional Software Development Life Cycle (SDLC), which focuses on how software is built and deployed, while the supply chain includes everything around it — dependencies, build systems, signing, and distribution.

In practice, this spans:

• Source code repositories – where developers push and manage code, and where access controls either hold or fail
• Open-source libraries and dependencies – external packages added to projects, often numbering in the hundreds
• CI/CD pipelines – the automated systems that compile, test, and package code for release
• Artifact storage and package registries – where build outputs are stored before distribution
• Code signing and release processes – the mechanisms that prepare and authenticate software for distribution
• Deployment channels – cloud platforms, app stores, enterprise environments, and update servers
• Update mechanisms – the systems that push patches and new versions to users

A typical SaaS application today pulls in around 203 direct dependencies and over 1,200 transitive ones. Most teams don’t have visibility into all of them.

The critical insight is this: if an attacker compromises any stage in that chain, they don’t need to break your application directly. They can inject malicious code somewhere upstream and let your own systems package and distribute it – and it reaches users looking completely legitimate. That’s what makes supply chain attacks so serious, and so scalable.

What is Software Supply Chain Security and Why It Matters

Software supply chain security is the practice of protecting everything involved in building and delivering your software – the code, the dependencies, the build pipeline, and the release process. It checks that nothing has been tampered with, compromised, or substituted at any stage between development and the end user.

The focus is on a few core things:

• Verifying that code hasn’t been altered unexpectedly at any stage
• Confirming that software actually comes from the publisher it claims to
• Securing build systems and release infrastructure from unauthorized access
• Preventing modifications at any point in the pipeline
• Ensuring users receive untampered software through trusted channels

A lot of teams confuse this with application security, and the two are related but not the same. Application security deals with vulnerabilities inside the running app – injection flaws, broken authentication, misconfigured access controls. Supply chain security sits a step earlier. It asks: was the software tampered with before it even got here?

To answer that question reliably, a few foundational things need to be in place.

Cryptographic Signing

When software is digitally signed, it carries proof of origin and integrity. The signing process uses asymmetric cryptography – a private key signs the artifact and a corresponding public key verifies it. If anything in the software changes after signing, the signature breaks. This model is built on a broader public key infrastructure, which ensures that trust can be verified across systems without exposing private keys.

Encryption in Transit

Communication between systems – repositories, build servers, artifact storage, deployment environments – all need to be encrypted. Not just external-facing traffic. Internal traffic too. A lot of breaches happen not because the perimeter failed, but because internal systems trusted each other too easily.

Key Management

Signing keys are essentially your identity as a software publisher. If someone gets access to them, they can produce malware that appears to come from you – signed, trusted, and delivered through your own channels. In higher-assurance environments, this protection is enforced using hardware security modules, which isolate keys from general system access and prevent extraction even if infrastructure is compromised.

Trust Maintenance Across the Software Lifecycle

Expired certificates, manually rotated keys and inconsistent signing practices are all operational gaps that attackers exploit. Automation keeps this consistent without relying on humans to remember. This is typically handled through certificate lifecycle management systems that automate issuance, renewal, rotation, and revocation across environments.

Key Components and Risks in the Software Supply Chain

Let’s break down where things usually go wrong based on how these systems actually behave in real environments.

Source Code & Repositories

Your repository is often treated as the “source of truth.” Which is exactly why it’s a target.

Common risks include:

• Unauthorized commits through compromised developer accounts
• Credential theft via phishing, token leaks or insecure storage
• Insider tampering, which is harder to detect than external attacks and leaves fewer traces

Third-Party and Open-Source Dependencies

Modern software depends heavily on external libraries. Sometimes hundreds of them.

The problem is, you don’t fully control them. Risks here include:

• Malicious packages intentionally published to public registries.
• Dependency confusion attacks, where attackers upload packages with the same name as internal dependencies but higher version numbers, tricking build systems into pulling the malicious version.
• Hidden vulnerabilities buried deep in dependency trees transitive dependency trees – packages that your direct dependencies depend on, which you may never have explicitly reviewed

Log4Shell (CVE-2021-44228) is a defining example here. Log4j was embedded as a transitive dependency in millions of applications. When the vulnerability was discovered, most organizations couldn’t even quickly determine whether they were exposed – because they had no visibility into their full dependency tree.

Build Systems and CI/CD Pipelines

CI/CD pipelines are where everything comes together. Code gets compiled, tested, packaged, and prepared for release. If this layer is compromised, attackers get a very powerful position.

Typical risks:

• Compromised build environments that modify code during the build
• Malicious scripts injected into pipeline steps
• Exposed tokens or credentials in environment variables or logs

SolarWinds is the textbook example. Attackers penetrated the vendor’s build environment, inserted a backdoor into signed Orion updates, and downstream customers installed it as a routine maintenance release.

Code Signing and Release Integrity

This is one of the key trust points. Digitally signed software tells users, “This came from us, and it hasn’t been altered.” But if the signing process is weak, or the keys are exposed, that trust collapses. This is exactly where understanding what a code signing certificate is and how it works becomes important, because the entire trust model depends on how that signature is created and verified. 

Risks include:

• Stolen or exposed signing keys
• Software being released without proper signing verification
• Weak or missing publisher identity checks

Signed malware is far more dangerous than unsigned malware. Users and systems trust it by default. That’s why protecting private keys is non-negotiable.

Software Distribution and Updates

Even if everything upstream is secure, distribution can still be a weak point.

Common risks:

• Man-in-the-middle attacks intercept downloads
• Tampered update packages
• Expired or poorly managed trust certificates

Update mechanisms are especially sensitive. If attackers compromise them, they can push malicious updates directly to users at scale. And because updates are expected, users rarely question them.

Top 5 Software Supply Chain Threats

These are not just edge cases but are patterns that have shown up repeatedly in real incidents. Some of them have affected thousands of organizations at once.

1. Dependency Confusion

   Researcher Alex Birsan demonstrated this in 2021: if an attacker publishes a package to a public registry with the same name as an organization’s internal package but with a higher version number, many build systems will automatically pull the public, malicious version instead. No alarms are raised, and no obvious signs. Just malicious code quietly entering your application.

2. Compromised Code Signing Keys

   If attackers access your signing keys, they don’t need to bypass security checks. They become a trusted publisher. Malware signed with legitimate keys often passes endpoint protections and user trust checks without much resistance. The damage isn’t just technical, but reputational. Every user who trusted your software trusted the attacker.

3. CI/CD Pipeline Breaches

   Build servers are attractive targets because they sit at a central point in the pipeline. Once compromised, attackers can:

   • Inject code into builds
   • Modify artifacts before release
   • Access secrets and credentials

   And since builds are automated, malicious changes can propagate quickly.

4. Malicious Open-Source Components

   Sometimes attackers contribute backdoors to popular libraries. Other times, they create seemingly useful packages that gain adoption over time. The tricky part is that these components often look legitimate. By the time the issue is discovered, they may already be widely used.

   The XZ Utils backdoor (CVE-2024-3094) from 2024 took this to an extreme – a pseudonymous actor called “Jia Tan” spent roughly two years earning maintainer trust through legitimate contributions before inserting a CVSS 10.0 backdoor targeting OpenSSH. The discovery was accidental: a Microsoft engineer noticed an unusual 500-millisecond SSH delay during performance testing and investigated.

5. Certificate Mismanagement

   Expired certificates don’t just cause outages – they break the certificate chain of trust that users and systems rely on to verify software authenticity. Poorly managed or improperly stored private keys cause something worse: they allow unauthorized entities to impersonate legitimate software sources, sign malware, and distribute it through trusted channels.

Software Supply Chain Security Best Practices

There’s no single control that secures the software supply chain. Each stage introduces its own trust boundary, and weaknesses at any point can be carried forward and distributed as legitimate software.

Digitally Sign All Software Releases

Every release should be signed – no exceptions. Digital signing guarantees:

• The software hasn’t been altered after the build
• The publisher can be verified
• Users and systems can trust what they’re installing

Unsigned software, especially in enterprise environments, is increasingly treated as suspicious by default.

Protect Signing Keys Using Secure Storage

Signing keys should never sit in plain files or loosely protected systems. Use hardened storage solutions like:

• Hardware Security Modules (HSMs) for the highest assurance environments
• Cloud-based key management services (AWS KMS, GCP KMS, Azure Key Vault)
• Controlled access environments with audit logging on every key usage

Access should be tightly restricted and monitored. If a key is exposed, assume compromise and rotate immediately.

Implement SBOMs

A Software Bill of Materials (SBOM) is a complete inventory of every component in your software – think of it as a nutritional label for what’s inside. Since US Executive Order 14028 mandated SBOMs for federal software procurement, and the EU Cyber Resilience Act made them a market access requirement, SBOMs have moved from “nice-to-have” to a regulatory baseline in many contexts.

The practical value is immediate: when a new vulnerability is disclosed, an SBOM lets you immediately answer “are we affected?” instead of spending days manually checking. Log4Shell made this case more powerfully than any whitepaper could. Two dominant formats are in wide use:

• CycloneDX – the OWASP standard, security-focused, and widely supported in tooling.
• SPDX – an ISO standard, stronger on licensing metadata, updated to v3.0 in 2024.

Tools like Syft and Grype can generate and consume SBOMs as part of your existing CI pipeline.

Adopt a Supply Chain Security Framework

Frameworks give you a structured way to think about maturity and prioritization. SLSA (Supply-chain Levels for Software Artifacts), developed at Google, provides four levels of build integrity and provenance tracking. SLSA Level 2 is achievable for most teams in two to four weeks using hosted build services, and would have made SolarWinds-style build tampering detectable. NIST SP 800-204D provides complementary CI/CD security guidance aligned with federal requirements.

Secure Communication Across the Development Pipeline

Data moves constantly between systems, repositories, build servers, artifact storage, and deployment environments. All of it needs to be encrypted. Not just external communication but internal traffic too.

Automate Certificate Lifecycle Management

Manual handling of certificates doesn’t scale well. Automating things like Certificate issuance, Renewal and rotation, Revocation when needed helps avoid outages and security gaps caused by expired or mismanaged certificates. It also reduces dependency on human intervention, which is often where mistakes creep in.

Monitor and Validate Dependencies

You don’t need to stop using open source — that’s not practical when 98% of modern codebases include it. But you do need visibility. That means:

• Knowing what dependencies you’re using and where they come from
• Running Software Composition Analysis (SCA) as part of your CI pipeline
• Pinning dependency versions with hash verification rather than pulling “latest”
• Using internal package mirrors or vetted registries to reduce exposure to malicious packages

OpenSSF Scorecard is worth mentioning here – it provides automated security health metrics for open-source projects across 18 checks, helping teams assess the risk of a dependency before they add it.

Enforce Least-Privilege Access in Build Environments

Build systems often have more access than they actually need. Limit it: only required resources should be accessible, secrets should be scoped tightly, and signing keys and credentials should never be broadly exposed across pipeline stages. If something goes wrong, the blast radius stays contained.

Quick Reference: Best Practices at a Glance

Conclusion

Software supply chain attacks don’t look like attacks. That’s what makes them work, and why perimeter security and runtime protections alone aren’t sufficient. Securing the supply chain means building verifiable trust at every stage.

The regulatory direction is clear. Executive Order 14028, the EU Cyber Resilience Act, and CISA’s 2025 SBOM guidance all point toward supply chain transparency as a baseline requirement. For organizations still treating it as optional, the question isn’t whether a supply chain incident will happen. It’s whether they’ll have the visibility to know when it does.

Related Articles:

• Why I Should Sign My Code and Verify it Before Publishing?
• Your Code Signing Certificate Has Expired – Now What?
• EV Code Signing vs. Regular Code Signing: Must-Know Differences
• 10 Key Factors for Choosing a Code Signing Certificate Provider
• How Much Does Code Signing Certificate Cost