27.2: SOC 2 and Supply Chain Controls¶

SOC 2 examinations have become the de facto standard for demonstrating security controls to enterprise customers, particularly for SaaS companies and technology service providers. When a prospective customer's security team requests evidence of your security practices, a SOC 2 report often tops their list. Yet many organizations approach SOC 2 as a checkbox exercise, implementing minimum controls sufficient to pass examination without building genuine security capability.

For supply chain security specifically, SOC 2 presents both opportunity and challenge. The Trust Services Criteria underlying SOC 2 examinations address vendor management, change control, and system integrity—all directly relevant to supply chain security. However, the criteria are principles-based rather than prescriptive, leaving significant interpretation to organizations and their auditors. Organizations that thoughtfully map supply chain security practices to Trust Services Criteria can demonstrate meaningful capability; those that treat supply chain as an afterthought will find their reports silent on increasingly important risks.

Trust Services Criteria Relevant to Supply Chains¶

SOC 2 examinations evaluate controls against the Trust Services Criteria (TSC) developed by the American Institute of Certified Public Accountants (AICPA). The criteria organize into five categories: Security (Common Criteria), Availability, Processing Integrity, Confidentiality, and Privacy. Security criteria are mandatory for all SOC 2 examinations; other categories are included based on organizational scope decisions.

Several Common Criteria directly address supply chain security concerns:

CC6: Logical and Physical Access Controls

CC6.1 through CC6.8 address access control implementation. For supply chain security, relevant requirements include:

• CC6.1: Restricting logical access to systems and data. This extends to third-party components and services—how do you control access to package repositories, build systems, and deployment infrastructure?

• CC6.6: Restricting access to system configurations. Dependency management configurations (package.json, requirements.txt, Gemfile) represent system configuration that affects security. Controls should address who can modify these files and how changes are reviewed.

• CC6.7: Restricting transmission of sensitive data. When your systems interact with external package repositories or third-party services, how is that communication secured?

CC7: System Operations

CC7.1 through CC7.5 address operational security, including detection and response capabilities:

• CC7.1: Detecting and monitoring security events. Supply chain attacks often manifest as anomalous behavior—unexpected network connections, unusual process execution, or modified binaries. Monitoring should extend to supply chain indicators.

• CC7.2: Monitoring system components for anomalies. This includes monitoring dependencies for newly disclosed vulnerabilities and detecting unexpected changes to component behavior.

• CC7.4: Responding to identified security incidents. Incident response procedures should address supply chain compromise scenarios—what happens when a critical dependency is found to contain malicious code?

CC8: Change Management

CC8.1 addresses change management controls, directly applicable to dependency updates:

• Changes to system components are authorized, designed, developed, configured, documented, tested, approved, and implemented

For supply chain security, this means dependency additions, updates, and removals should follow formal change management processes rather than ad-hoc modifications.

CC9: Risk Mitigation

CC9.2 specifically addresses vendor and business partner risk:

• The entity assesses and manages risks associated with vendors and business partners

This criterion provides the clearest hook for supply chain security controls, encompassing both service providers and software component suppliers.

Vendor Management Control Expectations¶

Auditors examining CC9.2 expect to see a formal vendor management program addressing the complete vendor lifecycle. For software supply chain purposes, "vendors" should include:

• Cloud service providers (AWS, Azure, GCP)
• SaaS tools used in development and operations
• Commercial software components
• Open source projects (particularly those critical to your product)
• Contractors and consultants with system access

Vendor Assessment and Selection

Controls should address how vendors are evaluated before engagement:

• Security questionnaires or assessments completed
• Review of vendor security certifications (SOC 2, ISO 27001)
• Evaluation of vendor security practices relevant to your use case
• Risk-based classification determining assessment depth

For software components, this translates to evaluating security posture before adoption—checking for known vulnerabilities, assessing project maintenance activity, reviewing security practices documented in the project.

Ongoing Monitoring

Vendor relationships require continuous oversight:

• Periodic reassessment (typically annual) of vendor security posture
• Monitoring for vendor security incidents or breaches
• Review of updated vendor SOC 2 reports or certifications
• Tracking vendor compliance with contractual security requirements

For software dependencies, ongoing monitoring means vulnerability scanning, tracking project health metrics, and responding to security advisories affecting components you use.

Vendor Inventory

Auditors expect a current inventory of vendors:

• Complete list of vendors with system access or data access
• Classification by risk level or criticality
• Documentation of security assessment status
• Contract and agreement tracking

Your SBOM serves as the inventory for software component vendors. Auditors increasingly recognize SBOMs as appropriate documentation for third-party component management.

Change Management for Dependencies¶

CC8.1 change management requirements apply to dependency changes just as they apply to application code changes. Organizations should establish controls addressing:

Authorization

• Who can add new dependencies to projects?
• What approval is required for dependency additions?
• Are there restrictions on dependency sources (e.g., only from official registries)?

Testing

• How are dependency updates tested before deployment?
• Are there automated tests validating dependency behavior?
• Is security testing performed on dependency changes?

Documentation

• Are dependency changes documented in change records?
• Is the rationale for dependency selection recorded?
• Are dependency versions tracked and auditable?

Implementation

• How are dependencies deployed to production?
• Are dependency changes separated from other changes for clarity?
• Can dependency changes be rolled back if issues arise?

Automated dependency update tools like Dependabot or Renovate support these controls by creating discrete pull requests for dependency updates, enabling review, testing, and approval workflows.

Evidence and Documentation Requirements¶

SOC 2 examinations require evidence that controls exist and operate effectively. For supply chain controls, prepare the following evidence categories:

Policies and Procedures

• Vendor management policy documenting assessment, monitoring, and offboarding procedures
• Change management policy explicitly covering dependency changes
• Software development security policy addressing supply chain practices

Technical Evidence

• SBOM files demonstrating component inventory
• Vulnerability scanning reports showing continuous monitoring
• Dependency update pull requests demonstrating change management
• Build pipeline configurations showing security controls
• Package repository configurations demonstrating source restrictions

Process Evidence

• Vendor assessment records and questionnaire responses
• Risk acceptance documentation for vendor relationships
• Meeting minutes from vendor review discussions
• Incident response records for supply chain events (if any occurred)

Monitoring Evidence

• Vulnerability scan reports across the audit period
• Dependency update logs showing remediation activity
• Alerting configurations for supply chain monitoring
• Security incident tickets related to dependencies

Type I vs. Type II Considerations¶

SOC 2 examinations come in two types:

Type I examinations assess whether controls are suitably designed at a specific point in time. Auditors review control design but do not test operating effectiveness over a period.

Type II examinations assess both design suitability and operating effectiveness over a period (typically 6-12 months). Auditors sample evidence across the period to verify controls operated consistently.

For supply chain controls, Type II examinations present additional challenges:

• Continuous evidence: You must demonstrate controls operated throughout the period, not just at examination time. Vulnerability scans, dependency updates, and vendor assessments must occur consistently.

• Change documentation: All dependency changes during the period should follow documented procedures with evidence available.

• Incident handling: If supply chain incidents occurred during the period, auditors will examine response effectiveness.

Organizations preparing for their first SOC 2 often begin with Type I to validate control design, then progress to Type II for ongoing assurance. If your supply chain controls are newly implemented, ensure they've been operating for the full Type II period before examination.

Working with Auditors on Supply Chain Topics¶

Auditor familiarity with software supply chain security varies significantly. Some auditors have deep technical backgrounds and understand dependency management, SBOMs, and build pipeline security. Others approach supply chain through traditional vendor management lenses, potentially missing technical nuances.

This gap became apparent following high-profile supply chain attacks in 2020-2021. Audit firms began including supply chain security in SOC 2 examinations, but many auditors lacked software development experience. Organizations found themselves in situations where auditors who could competently evaluate database access controls struggled to understand why a transitive dependency three levels deep mattered for security. The result: inconsistent examination approaches where some organizations faced rigorous technical scrutiny while others received only cursory review of dependency management.

Educating Your Auditor

Be prepared to explain:

• What software dependencies are and why they matter (use the SolarWinds or Log4Shell incidents as concrete examples of impact)
• How your SBOM relates to vendor inventory requirements (position it as "automated vendor discovery for software components")
• Why automated dependency updates support change management (show how Dependabot/Renovate creates auditable pull requests with approval workflows)
• How vulnerability scanning provides continuous monitoring (demonstrate scan frequency, alerting thresholds, and remediation tracking)

Frame explanations in terms auditors understand—map technical controls to Trust Services Criteria language rather than expecting auditors to translate. When an auditor asks about "vendor oversight," show them your SBOM and vulnerability scanning dashboard rather than attempting abstract explanations of dependency management.

Proactive Control Mapping

Prepare a mapping document showing:

This mapping helps auditors understand how your technical controls satisfy their criteria.

Scoping Discussions

During audit planning, clarify supply chain scope:

• Which systems and applications are in scope?
• Are open source dependencies considered "vendors" for CC9.2 purposes?
• What level of component visibility is expected (direct dependencies, transitive)?
• How will auditors sample dependency changes?

Establishing clear expectations prevents misunderstandings during fieldwork.

Common Gaps and Remediation¶

Organizations frequently encounter gaps in these areas:

Gap: Incomplete Dependency Inventory

Organizations may have SBOMs for production applications but miss dependencies in: - Development and build tools - CI/CD pipeline components - Infrastructure-as-code modules - Container base images

This gap frequently surfaces during audit fieldwork. An auditor asks to see the organization's vendor inventory for CC9.2, and the security team provides a spreadsheet listing AWS, GitHub, and a dozen SaaS tools. The auditor then asks: "What about the open source libraries in your application?" Security points to their SBOM. "And your build system dependencies?" Blank stares. Organizations discover they've inventoried vendors they pay, but not the hundreds of components their applications actually depend on.

Remediation: Extend SBOM generation to all systems in SOC 2 scope. Use tools like syft or trivy to scan container images and runtime environments. For CI/CD pipelines, generate SBOMs of the runner images themselves—if your GitHub Actions workflows use actions from the marketplace, those represent supply chain dependencies requiring inventory.

Gap: Informal Dependency Updates

Dependencies are updated ad-hoc without formal change management—developers update packages directly without review or documentation.

Remediation: Implement automated dependency update tools that create pull requests requiring approval. Configure branch protection to enforce reviews.

Gap: Missing Vendor Classification for Components

Traditional vendor management programs classify service providers but don't address software components.

Remediation: Extend vendor classification framework to include critical dependencies. Document risk-based criteria for component assessment depth.

Gap: Reactive-Only Vulnerability Management

Organizations scan for vulnerabilities but lack evidence of consistent monitoring over the audit period.

The typical pattern: security runs a dependency scan in January when preparing for SOC 2. The scan identifies 47 high-severity vulnerabilities. The team remediates 40 of them. By April, when the auditor arrives, new vulnerabilities have been disclosed affecting components that were clean in January—but there's no evidence the organization detected them. The auditor sees only the January scan and current state, missing the three months of potential exposure in between.

Remediation: Implement scheduled vulnerability scans with documented frequency (weekly minimum for SOC 2 Type II). Configure alerting for new vulnerabilities above severity thresholds. Maintain scan history for audit evidence—many scanning tools provide compliance reports showing continuous monitoring across the audit period. For Type II examinations, auditors will sample across months, requiring proof that monitoring occurred consistently, not just at examination endpoints.

Gap: No Supply Chain Incident Response

Incident response procedures address traditional security incidents but don't specifically address supply chain compromise scenarios.

Remediation: Add supply chain compromise scenarios to incident response playbooks. Conduct tabletop exercises addressing dependency compromise.

Recommendations¶

We recommend organizations preparing for SOC 2 examination:

1. Map supply chain controls explicitly to Trust Services Criteria, documenting how each control satisfies specific requirements

2. Treat SBOMs as vendor inventory documentation, ensuring they're generated consistently and retained for audit periods

3. Formalize dependency change management through automated tools that create auditable approval workflows

4. Maintain continuous evidence of vulnerability scanning and remediation throughout the audit period

5. Prepare auditor education materials explaining supply chain security concepts in compliance terminology

6. Include supply chain scenarios in incident response procedures and testing

7. Start early for Type II examinations—controls must operate consistently for the full period, not just at examination time

SOC 2 provides a valuable framework for demonstrating supply chain security controls to customers and stakeholders. Organizations that thoughtfully integrate supply chain security into their compliance program will find SOC 2 examinations validate genuine capability rather than create artificial compliance burden.