How to Secure CI/CD Pipelines from Supply Chain Risks

CI/CD pipelines streamline development and deployment but are vulnerable to supply chain attacks. These risks can lead to malicious code entering production, regulatory fines, financial losses, and reputational damage. To protect pipelines, focus on:

• Source Code Security: Use branch protection policies, secure coding standards, and regular audits.
• Dependency Management: Scan third-party libraries with SCA tools, maintain an SBOM, and validate package integrity.
• Secrets Management: Avoid hardcoding credentials, use centralised secret management tools, and rotate keys regularly.
• Build Environment Security: Enforce RBAC, restrict network access, and use dual-approval for critical actions.
• Artifact Integrity: Sign artifacts cryptographically and validate signatures before deployment.
• Continuous Monitoring: Log all pipeline activities, use anomaly detection tools, and integrate with SIEM systems.
• Access Controls: Implement zero-trust models, review permissions quarterly, and follow the principle of least privilege.
• Incident Response: Prepare playbooks for containment, forensic analysis, and recovery.

Securing CI/CD pipelines reduces risks, ensures compliance, and protects your organisation from costly breaches. Start with these steps and expand as needed.

Supply Chain Security in CI/CD Pipelines: Practical Insights for Cloud-Native Development

Securing Source Code and Dependencies

The CI/CD source stage plays a critical role in merging code with dependencies, but it also represents a prime target for malicious actors [1]. Protecting this stage is key to reducing supply chain risks in CI/CD pipelines. A layered approach that combines secure practices and automated controls is essential.

Adopting Secure Coding Standards

Secure coding standards help development teams maintain consistent practices and reduce the risk of vulnerabilities making their way into the pipeline. Automated tools, paired with expert reviews, can catch potential issues early.

Branch protection policies are a cornerstone of repository security. These policies should mandate approvals from designated security reviewers before code merges, ensuring unauthorised or malicious changes are blocked [1]. Regular code reviews by multiple experts help identify risks like hardcoded credentials, insecure API usage, and injection vulnerabilities.

Effective repository access controls are another critical measure. Assigning roles and permissions carefully, restricting write access to active branches, and using multi-factor authentication for elevated privileges all contribute to a secure pipeline [2]. By following the principle of least privilege, access is limited to those who genuinely need it, reducing potential risks. Regular audits and updates to permissions further strengthen security.

Adopting GitOps practices ensures that all infrastructure changes are reviewed and logged, creating a complete audit trail [1]. Involving development teams in regular security assessments and penetration testing not only identifies vulnerabilities but also builds a deeper understanding of security practices [1].

These measures should also extend to third-party components to ensure a secure pipeline.

Scanning Dependencies for Vulnerabilities

Third-party dependencies are often a weak link in the supply chain, making rigorous scrutiny a necessity [1]. Software Composition Analysis (SCA) tools are central to managing dependency vulnerabilities. By maintaining a Software Bill of Materials (SBOM), organisations can inventory their dependencies and scan them regularly with SCA tools [6]. Combined with Static Application Security Testing (SAST), these tools continuously monitor for vulnerabilities and assess their severity before deployment [2][3].

Scanning dependencies should be an ongoing process, taking place when new dependencies are added, during builds, and before deployment. Beyond scanning, organisations need to validate the integrity of new dependencies or container images [6]. Addressing vulnerabilities means prioritising based on severity, understanding the specific risks in context, and mitigating them through updates, patches, or alternative components.

Dependencies should always come from trusted sources. This involves verifying package signatures, confirming the publisher's identity, and ensuring there has been no tampering. Actively maintained projects with responsive security teams are generally safer than abandoned or outdated libraries. Structuring repositories to establish clear security boundaries and employing drift detection to spot unauthorised changes further bolsters security [1].

Managing Secrets Securely

Securing credentials is critical to safeguarding your CI/CD environment from supply chain breaches. Proper storage, access, and rotation of API keys, passwords, and other sensitive information are essential [1]. Misconfigurations in CI/CD systems, as seen in the Uber breach, can lead to serious vulnerabilities [2].

Secrets should never be hardcoded in repositories or configuration files [8]. Tools like git-leaks can identify hardcoded secrets, preventing accidental exposure of credentials that could give attackers direct access. Automated scanning tools should continuously monitor all branches and pull requests, blocking commits that include exposed secrets [8].

Instead of embedding credentials in code, organisations should use secure, centralised systems for managing environment variables [2]. Secrets management solutions should encrypt credentials during storage and transit, enforce granular access controls, and log all access activities. Regular rotation of sensitive credentials - ideally automated - adds another layer of security [1]. Developers should only access secrets via authenticated requests, and credentials should never appear in logs or build artefacts. Using distinct credentials for development, staging, and production environments also limits the impact of any compromise.

Secret scanning tools should be customised to detect patterns specific to the organisation, such as internal API key formats. When exposed secrets are found, automated actions - like alerting developers, blocking code merges, or triggering credential rotation - can mitigate risks. Periodic scans of repository histories can uncover previously exposed secrets, allowing organisations to rotate them as needed.

Government bodies like the NSA and CISA have emphasised the importance of proper secrets management in their CI/CD security guidance [2]. Similarly, NIST highlights two key goals: defending the CI/CD pipeline and ensuring the integrity of upstream sources and artefacts [7]. By aligning with these frameworks, organisations can adapt their security practices to stay ahead of evolving threats.

For more in-depth advice on protecting your CI/CD pipelines, Hokstad Consulting offers tailored expertise to address your specific needs.

Protecting Build and Artifact Stages

Securing the build and artifact stages is a key step in safeguarding your CI/CD supply chain. These stages involve combining source code with dependencies and libraries to create executable files and artifacts [1]. Unfortunately, this critical process can also be a prime target for attackers looking to inject malicious code or compromise deployment integrity. A robust security strategy ensures the build environment is protected, all components are verified before deployment, and any tampering is prevented.

Securing the Build Environment

To keep the build environment secure, it’s essential to enforce strict role-based access control (RBAC) [2]. Developers should have limited access, build engineers may require broader permissions, and only authorised personnel should approve production deployments [1].

Build systems should also be isolated from general network traffic to minimise exposure to potential breaches [5]. Outbound connections should be restricted to only the services absolutely necessary.

Sensitive operations, such as production deployments or infrastructure changes, should require a dual-approval process [1]. This means at least two authorised individuals must review and approve these actions. Automation accounts used in builds should operate under strict privilege boundaries, accessing only the resources they need [1].

Comprehensive logging is another cornerstone of build environment security. Logs should capture user access, changes, deployment times, and any anomalies [1]. Centralised audit logging systems can help detect suspicious patterns, like off-hours access attempts or unusual configuration changes [1]. Regularly reviewing access permissions ensures they remain appropriate as team roles evolve [1].

Once the build environment is secured, the next step is to ensure container images are safe and free from vulnerabilities.

Scanning and Validating Container Images

Container images are a staple of modern CI/CD pipelines, but they can introduce risks if not properly vetted [4]. Container security scanning is crucial for identifying vulnerabilities, malware, and misconfigurations before images are deployed [1].

Scanning should focus on outdated dependencies, misconfigurations, and elevated privileges within images [4]. Additionally, ensuring images come from trusted sources helps prevent supply chain attacks, where compromised images are uploaded to public registries.

To mitigate these risks, enforce strict policies about image sources. Use only approved registries and consider maintaining private registries for internally developed containers. Vulnerability assessments should occur at multiple stages: during image creation, throughout the build process, and before deployment [4].

Infrastructure-as-Code (IaC) files, such as those created with Terraform or CloudFormation, should also be scanned for insecure configurations [1]. Integrating automated IaC scanning into the CI/CD pipeline helps catch potential issues before they reach production [1].

After validating container images, it's critical to safeguard the integrity of all built artifacts.

Ensuring Artifact Integrity

Protecting artifact integrity is essential to prevent tampering after the build process [1]. Using cryptographic signing for all build artifacts creates a verifiable record of what was built and by whom [1]. Deployment systems should validate these signatures to confirm that artifacts remain unchanged since their creation.

The SLSA (Supply-chain Levels for Software Artifacts) framework offers a structured approach to securing build systems against tampering [3]. Each level of SLSA introduces stronger guarantees about artifact integrity. At higher levels, organisations can verify that artifacts were built from specific source code using verified processes without unauthorised modifications.

NIST SP 800-204D also highlights artifact integrity checks as part of software supply chain security [3]. This framework integrates supply chain security into DevSecOps workflows and recommends continuous Software Bill of Materials (SBOM) generation and validation [3].

Runtime security monitoring adds another layer of protection by offering real-time visibility into build activities [5]. Monitoring CI/CD runners can help detect unusual behaviours such as unexpected outbound traffic, unauthorised file modifications, or attempts to access sensitive data [5]. Tools like Harden-Runner can provide detailed insights into build processes and flag suspicious activity [5].

To enhance monitoring, define baseline activity profiles for each build workflow [5]. Anomaly detection systems can then identify deviations from these baselines. For instance, if a build process suddenly initiates network calls or accesses memory it never touched before, this should trigger an investigation [5]. Automated containment measures can quarantine suspicious builds and initiate additional security checks [1].

Finally, build logs should be scanned for leaked secrets or suspicious entries. Automated scans can catch credentials or tokens that might have been inadvertently exposed during the build process, preventing them from being stored in artifact repositories or reaching later stages of the pipeline [5].

Documenting security test results is critical for compliance and audit purposes. This documentation should detail what was tested, any vulnerabilities found, and how they were addressed [1]. Such records are invaluable for demonstrating adherence to frameworks like the OWASP Top 10 CI/CD Security Risks, which focus on issues like poor credential management, pipeline poisoning, and insecure configurations [3].

For organisations looking for expert guidance, Hokstad Consulting offers tailored DevOps services to strengthen CI/CD pipelines while maintaining development speed.

Implementing Continuous Monitoring and Response

After securing the build and artefact stages, maintaining visibility across your CI/CD pipeline is crucial. Continuous monitoring adds a real-time layer of security, enabling you to detect threats as they arise. This approach transforms your pipeline from a potential weak spot into a system that can identify and respond to supply chain attacks before they impact production.

Monitoring Pipeline Activities

The first step in effective monitoring is detailed logging across every stage of your pipeline. This includes tracking activities from the moment code is committed to its deployment in production [2, 5]. Your logging system should capture key events like code commits, build processes, deployment actions, and infrastructure changes. Keep an eye out for unusual patterns, such as commits made at odd hours, suspicious build artefacts, or unexpected resource usage [1]. Access logs are equally vital, as they provide insight into who accessed the pipeline, when, and what actions they performed.

Set up alerts for critical activities to ensure a swift response to potential incidents [4]. For instance, logins from unfamiliar locations, access outside regular business hours, or attempts to escalate privileges should trigger immediate alerts.

Centralised audit logs are another essential tool. They not only help track unauthorised changes but also support forensic investigations when needed [1].

Beyond basic logging, it's important to monitor specific metrics that could indicate a supply chain attack. For example, a spike in build times might suggest malicious background processes, while unexpected outbound network connections could be a sign of data exfiltration. Similarly, unauthorised changes to file systems or delays in dependency resolution might point to repository tampering [2, 5, 7]. This comprehensive approach to logging lays the groundwork for automated anomaly detection.

Using Anomaly Detection Tools

Once you have robust logging in place, anomaly detection tools can take your threat identification to the next level. Traditional security systems that rely on known threat signatures often fail to catch advanced supply chain attacks. In contrast, machine learning-based anomaly detection tools establish baseline metrics for normal activity and alert your security team when unusual patterns emerge [1]. These tools analyse historical data - covering build times, resource usage, network traffic, and deployment frequencies - to understand what normal looks like. This allows them to flag deviations, such as unexpected outbound traffic, unusual file changes, or abrupt increases in build duration, even if no known attack pattern is present [5].

Customising these baselines to match each workflow improves accuracy and reduces false positives. For instance, while a data-intensive pipeline might naturally consume significant resources at certain times, a simple web application build should show consistent and modest resource use.

Real-time monitoring tools, like Harden-Runner agents, add another layer of defence. These agents observe runner behaviour in real time, detecting anomalies such as unauthorised file changes, suspicious process executions, or unexpected network activity. By comparing current behaviour to established baselines, they can immediately flag and address potential threats [5].

Integrating with Incident Response Systems

For a streamlined security process, integrate your CI/CD pipeline logs and events with Security Information and Event Management (SIEM) or Security Orchestration, Automation, and Response (SOAR) platforms like Splunk or IBM QRadar [1]. These systems enable automated workflows for threat detection and response. For example, if anomalous activity is detected, the pipeline can automatically quarantine suspicious builds and initiate additional security checks to prevent compromised code from being deployed [1]. Suspicious deployments can also be rolled back automatically, and affected components isolated.

SIEM and SOAR platforms excel at correlating data from multiple sources, identifying complex attack patterns that might not be apparent from individual logs. A series of minor events - such as a configuration change, access during unusual hours, or an unexpected dependency update - might collectively signal a coordinated supply chain attack. By integrating security checks throughout the pipeline, these platforms can halt the process if a threat is detected [1]. For example, builds showing unusual resource usage or network behaviour can be blocked from progressing to the next stage. These measures should be tailored to your organisation's risk profile and the sensitivity of the applications being deployed.

For expert advice on monitoring and securing your CI/CD pipeline, Hokstad Consulting offers bespoke DevOps transformation services.

Establishing Access Controls and Incident Response Plans

Securing your CI/CD pipeline isn’t just about protecting code - it’s about having the right access controls and a solid plan for responding to incidents. Weak access policies or unclear response procedures can leave your pipeline exposed to supply chain attacks. Building on earlier steps like securing code and builds, this section dives into how to manage access effectively and prepare for incidents.

Implementing Zero-Trust Access Models

The zero-trust model flips traditional security thinking on its head. Instead of assuming anyone inside your network is safe, it requires strict verification for every access request - whether it’s for repositories, build systems, deployment tools, or artefact registries - no matter where the request originates [4]. The idea is simple: verify every request and only grant the permissions absolutely necessary for the task.

This approach works hand-in-hand with other security measures by ensuring no single access point becomes a weak link. It reduces the risks tied to implicit trust and helps detect unauthorised access attempts. Even if a breach happens, it limits how far an attacker can move within your system. Adding extra layers, like the four-eyed principle - where critical operations need independent approval - further reduces risks from both errors and malicious actions. Automation accounts, often with elevated privileges, should also have tightly defined boundaries, allowing them to do only what’s required.

Following the principle of least privilege is crucial. This means granting access only to the resources a role or individual needs. Regular audits of all roles within the CI/CD pipeline, combined with role-based access control (RBAC), can keep permissions aligned with responsibilities - especially as team members change roles or leave the organisation.

Creating Incident Response Playbooks

Access controls are just one piece of the puzzle. You also need to be ready for incidents with a well-defined response plan. A CI/CD-specific incident response playbook is essential for managing containment and recovery efficiently. Start by clearly identifying what qualifies as a security incident in your pipeline - unauthorised code commits, unusual build behaviour, or compromised credentials, for example.

The playbook should include detailed containment steps, like isolating affected components or rolling back to earlier, secure builds. Automated processes can play a big role here, such as quarantining suspicious builds or triggering extra security checks when anomalies are detected.

Forensic analysis is another key part of the plan. Specify which logs to collect and how to preserve system states to better understand the breach and prevent it from happening again.

Effective communication is also critical. Your plan should outline who needs to be informed - security teams, developers, management, or even customers - and in what order. Recovery steps should focus on restoring normal operations quickly and making any necessary security improvements to avoid a repeat incident.

Conducting Regular Access Reviews

Access permissions aren’t static - they need to evolve with your team. Over time, as people change roles or leave, permissions can pile up and no longer reflect current needs. Regular access reviews ensure permissions remain appropriate and unnecessary access is removed. Aim to review permissions at least quarterly, or even more often for high-risk systems or during times of significant team changes.

Unused permissions - those inactive for 30 to 90 days - should be flagged for removal. Pay special attention to service accounts and automated processes, ensuring their elevated privileges are still justified. Manager certifications can help maintain accurate records of access needs.

Centralised audit logs are invaluable for tracking who accessed what and when. These logs not only support security monitoring but also help with compliance. Regular reviews prevent outdated permissions from weakening your pipeline’s defences. And by streamlining workflows for adjusting access quickly, you can ensure permissions are updated or revoked as soon as roles change, keeping security tight without slowing down development.

For organisations needing expert help with access controls and incident response, Hokstad Consulting offers tailored DevOps transformation services to strengthen your pipeline’s security while maintaining development speed.

Conclusion

Protecting your CI/CD pipeline is an ongoing effort that safeguards your organisation from breaches while maintaining development efficiency. The strategies outlined here combine to form a layered security approach, addressing risks at every stage - from source code to production deployment.

Strong CI/CD security not only ensures compliance with regulations like GDPR and PCI DSS but also helps reduce the costs and disruptions associated with incident response. Beyond meeting legal requirements, these practices offer operational advantages. For instance, effective security can reduce regulatory scrutiny and even lower cyber insurance premiums. A well-structured security programme also provides clear audit trails and compliance documentation, which are invaluable for satisfying stakeholders, insurers, and regulators. Additionally, automated compliance checks aligned with predefined standards can simplify compliance processes and offer ongoing visibility into your application’s security posture [4].

Start with the basics and build gradually. If resources are limited, focus first on essential controls such as enforcing least privilege access, managing secrets securely, and automating code scans. From there, move on to securing build environments, scanning container images, and incorporating continuous monitoring. This phased approach ensures your security measures grow alongside emerging threats.

To stay ahead, schedule quarterly reviews to assess your defences against new vulnerabilities. Subscribe to updates from organisations like NIST, CISA, and the Open Source Security Foundation. Regularly conduct security assessments and penetration tests that focus on your CI/CD pipelines, involving development teams to enhance their security awareness [1]. Use metrics like detection and remediation times to evaluate your programme’s effectiveness. Analysing these metrics quarterly can help identify trends, assess the performance of your controls, and guide resource allocation.

For tailored expertise, Hokstad Consulting provides specialised DevOps transformation services to bolster pipeline security without compromising speed. Their knowledge in DevOps optimisation and automation can help you establish a resilient security framework that safeguards your operations while enabling continuous innovation.

FAQs