For critical suppliers that affect safety, product quality, or regulated data, SR control documentation should be driven by a risk-based supplier tiering model and mapped to your own security and quality management systems. You will not collect the same depth from every vendor, and some evidence will only be available under NDA or on-site review.
1. Governance and contractual documentation
At a minimum for critical suppliers, you should expect:
- Master supply / service agreement with security and confidentiality clauses that reference applicable standards or frameworks.
- Data processing and protection terms covering regulated data (e.g., export-controlled, PHI, PII, customer proprietary), including roles, subprocessors, and data location.
- Service level and availability commitments for systems that impact production scheduling, quality release, or maintenance windows.
- Change notification requirements (e.g., infrastructure changes, hosting moves, key personnel changes, material subcontracting, EOL announcements).
- Right-to-audit / right-to-assess language so you can review evidence without assuming compliance or certification.
2. Information security and SR control documentation
For SR-related controls (for example, in the sense of IEC 62443 or similar frameworks), useful supplier documentation typically includes:
- Information security policy overview (high-level, not full internal manuals), showing scope, governance, and alignment to any named standards.
- Network and system security approach for the product or service you use, including segmentation assumptions, remote access mechanisms, and customer responsibilities.
- Access control model (how accounts, roles, and privileges are provisioned, reviewed, and revoked for your environment and for their support staff).
- Remote support procedures (how remote sessions are initiated, authenticated, logged, and approved, and what emergency access looks like).
- Backup and recovery strategy for hosted or managed systems that affect manufacturing operations or quality data.
The depth of what you request should be proportional to supplier impact and the maturity of their own security program. Many OT and equipment vendors will only provide summaries rather than detailed diagrams.
3. Secure development, configuration, and change control
Because SR controls are easily broken by uncontrolled changes, you should ask critical suppliers for documentation that shows how they manage change:
- Secure development practices at a summary level (code review, dependency management, static/dynamic testing) for software, firmware, or configuration packages.
- Configuration management of delivered systems (how versions of PLC logic, recipes, or application configurations are controlled and identified).
- Formal release notes for software/firmware/patches that clearly state:
- Version identifiers and release dates
- Security-related fixes and known issues
- Upgrade prerequisites and rollback options
- Change notification process for security-relevant changes affecting network ports, authentication methods, encryption, or logging.
- End-of-life and end-of-support policies for hardware, OS versions, and major software releases.
4. Vulnerability, patch, and incident handling documentation
For systems connected to your OT/IT networks or handling regulated data, you should collect evidence of how the supplier manages vulnerabilities and incidents:
- Vulnerability management process overview including intake, triage, remediation targets, and communication methods with customers.
- Patch management policy and typical release cadence for security fixes, including how they differentiate security vs functionality updates.
- Public advisory practices (e.g., product advisories, security bulletins) and how you can subscribe or be notified.
- Security incident response process at a summary level: detection, containment, investigation, customer communication; including RACI on who does what.
- Notification commitments for breaches, compromised credentials, or issues that may affect integrity, availability, or confidentiality of your data or operations.
5. Audit, certification, and assurance evidence
Independent assurance is useful but not a guarantee of compliance or security performance in your specific context. For critical suppliers, you can reasonably request:
- Relevant certifications or attestations (e.g., SOC 2 type II reports, ISO 27001 certificates, IEC 62443 component/system certificates where applicable), understanding they may be scoped.
- Summary of audit scope and exclusions so you know which products, sites, and services were actually assessed.
- High-level remediation status for significant findings that could affect your SR controls, where the supplier is willing to share this.
In heavily regulated environments, do not rely solely on third-party certifications. Combine them with your own technical validation, supplier assessments, and change control.
6. Product lifecycle and integration assumptions
Because industrial and regulated assets often run for decades, SR controls must be evaluated across the full product lifecycle and in coexistence with legacy systems:
- Product lifecycle roadmap summaries indicating planned support horizons for major versions that you depend on.
- Supported environment matrices (OS, database, browser, PLC/drive firmware) to avoid unplanned upgrades just to keep vendor support.
- Integration responsibility matrix clarifying which party is responsible for:
- Network segmentation, firewall rules, and zoning
- Identity and access management integration
- Log collection and monitoring
- Backup and disaster recovery implementation
- Known limitations or constraints of SR-relevant features when used with legacy or multi-vendor stacks.
This is especially important where a full system replacement is unrealistic due to validation effort, qualification burden, or downtime risk. In such cases, documentation needs to be explicit about residual risks and compensating controls you must implement around the supplier’s product.
7. What to formalize internally
To keep this manageable and auditable, define an internal standard for SR documentation from critical suppliers:
- Supplier tiering and SR impact criteria (e.g., Tier 1: network-connected OT equipment; Tier 2: SaaS managing batch or device history records).
- Minimum evidence list per tier referencing the categories above.
- Document control rules for how you store, review, and periodically refresh supplier evidence.
- Validation and change control linkage so that new supplier evidence (e.g., major patch policies, new remote access methods) triggers impact assessment on validated systems.
Ultimately, the specific documents you can obtain will depend on the supplier’s maturity, your contractual leverage, and your regulatory context. Focus on obtaining enough documented evidence to:
- Understand how their SR controls actually work.
- Identify which responsibilities fall to you vs the supplier.
- Support your own risk assessments, validation, and audits without implying guaranteed compliance.
