1. Purpose
The Supplier Monitoring & Review Policy establishes the organization’s requirements for continuously monitoring and periodically reviewing suppliers that provide products, services, technology, infrastructure, software, or other capabilities that may affect information security, privacy, business operations, customers, or regulatory obligations.
The policy ensures that supplier risk is not assessed only at onboarding.
Supplier relationships should be monitored throughout their lifecycle to identify:
- Security incidents
- Changes in supplier risk
- Changes in services or technology
- Changes in access
- New vulnerabilities
- Changes in data processing
- New subprocessors
- Changes in certifications or assurance
- Availability or performance issues
- Contractual issues
- Business continuity concerns
- Concentration or dependency risks
- End-of-life or service discontinuation
- Other material changes
The objective is to ensure that supplier risks remain visible, assessed, controlled, and appropriate throughout the supplier relationship.
2. Policy Statement
The organization shall monitor and review suppliers using a risk-based approach.
The level and frequency of monitoring shall be determined by factors including:
- Supplier criticality
- Information handled
- System or production access
- Privileged access
- Customer impact
- Business dependency
- Regulatory requirements
- Security risk
- Availability requirements
- Contractual requirements
- Supplier performance
- Subprocessor dependency
- Concentration risk
Critical suppliers shall receive enhanced monitoring and more frequent review than suppliers with limited business or security impact.
3. Scope
This policy applies to relevant:
- Cloud providers
- SaaS providers
- IaaS/PaaS providers
- Software suppliers
- Managed service providers
- IT service providers
- Security providers
- Consultants
- Contractors
- Data processors
- Subprocessors
- Payment providers
- Backup providers
- Network providers
- Development partners
- Technology suppliers
- Critical third-party services
- Other external parties that may affect the organization’s information security or business operations
The policy may be applied proportionately to low-risk suppliers.
4. Core Supplier Monitoring Principle
The supplier lifecycle should follow:
Supplier → Service → Information → Access → Risk → Requirements → Contract → Onboarding → Monitoring → Review → Reassessment → Treatment → Offboarding
Monitoring should answer:
Has anything changed that could alter the supplier’s security, privacy, operational, or business risk?
5. Supplier Classification
Suppliers should be classified according to risk and criticality.
Low
Examples:
- Limited business impact
- No sensitive information
- No production access
- Easily replaceable service
Medium
Examples:
- Important internal service
- Confidential information
- Moderate business dependency
- Application access
High
Examples:
- Sensitive information
- Important business process
- Production access
- Significant customer impact
Critical
Examples:
- Critical production infrastructure
- Customer-facing service
- Privileged access
- Large volumes of sensitive/customer information
- Significant regulatory dependency
- Difficult-to-replace service
- Major business continuity dependency
These classifications should align with the organization’s approved risk methodology.
6. Supplier Monitoring Model
Supplier monitoring should operate at several levels.
Continuous/Regular Monitoring
Monitor relevant:
- Security incidents
- Vulnerabilities
- Service outages
- Security advisories
- Material changes
- SLA performance
- Security alerts
- Supplier notifications
Periodic Review
Conduct formal supplier reviews according to risk.
Event-Driven Review
Perform an additional review when a significant change or incident occurs.
7. Monitoring Areas
The organization should monitor, where relevant:
| Area | Monitoring Focus |
|---|---|
| Security | Incidents, vulnerabilities, security posture |
| Access | Supplier accounts and privileges |
| Privacy | Data processing and privacy changes |
| Availability | Service uptime and outages |
| Performance | SLA/KPI performance |
| Compliance | Certifications and regulatory requirements |
| Assurance | SOC reports, audits, testing |
| Subprocessors | New or changed downstream providers |
| Technology | Major technology changes |
| Data | Location, processing, retention |
| Contract | Expiry, amendments, obligations |
| Business Continuity | Recovery capability |
| Financial/Operational | Supplier stability |
| Concentration | Dependency on supplier |
| Exit | Replacement and migration capability |
Only monitoring areas relevant to the supplier should be applied.
8. Security Monitoring
Monitor significant changes in the supplier’s security posture, such as:
- Security incidents
- Confirmed breaches
- Major vulnerabilities
- Security advisories
- Compromised credentials
- Unauthorized access
- Significant control failures
- Security-test findings
- Changes in security certifications
- Changes in security leadership where relevant
- Material changes to security architecture
Significant security events should trigger reassessment where appropriate.
9. Supplier Access Monitoring
For suppliers with system access, monitor:
- Active supplier accounts
- Individual account usage
- Privileged access
- MFA status
- Production access
- Remote access
- Dormant accounts
- Temporary accounts
- Service accounts
- Access changes
- Failed authentication attempts
- Unusual activity where monitoring is available
Supplier access should remain:
Authorized → Necessary → Least Privileged → Monitored → Periodically Reviewed
10. Supplier Access Review
Access reviews should confirm:
| Question | Yes/No/N/A |
|---|---|
| Is the supplier still providing the service? | |
| Is access still required? | |
| Are the users still authorized? | |
| Are individual accounts used? | |
| Is MFA enabled? | |
| Is privileged access still required? | |
| Is production access still required? | |
| Are inactive accounts removed? | |
| Are former supplier personnel removed? | |
| Are access levels appropriate? | |
| Is evidence retained? |
Unnecessary access should be removed promptly.
11. Supplier Performance Monitoring
Where applicable, monitor:
- SLA performance
- Availability
- Incident response time
- Support response time
- Service quality
- Delivery performance
- Security obligations
- Corrective-action completion
- Contractual performance
Example:
| KPI/KRI | Target | Actual | Status |
|---|---|---|---|
| Availability | |||
| Incident response | |||
| Critical findings overdue | |||
| Security review completion | |||
| SLA compliance |
Business-performance monitoring and security monitoring may be combined where practical.
12. Security Assurance Monitoring
For relevant suppliers, periodically review available assurance information such as:
- ISO 27001 certification
- SOC 1/SOC 2 reports
- Independent assessment reports
- Penetration-test summaries
- Security questionnaires
- Business continuity test results
- Disaster recovery test results
- Vulnerability-management evidence
The organization should consider:
- Validity period
- Scope
- Exceptions
- Findings
- Management responses
- Relevance to the service provided
A certification should not automatically be treated as evidence that every supplier-specific risk is acceptable.
13. Certification and Assurance Expiry
Track relevant assurance expiry dates.
| Supplier | Assurance | Expiry | Review Required | Status |
|---|---|---|---|---|
Where assurance expires or becomes unavailable:
- Contact the supplier.
- Determine current assurance status.
- Assess the impact.
- Identify alternative evidence.
- Reassess supplier risk if necessary.
- Record the decision.
14. Vulnerability Monitoring
For technology suppliers, monitor:
- Critical vulnerabilities
- Supplier security advisories
- Product vulnerabilities
- Vulnerable versions
- End-of-life technologies
- Compromised components
- Security patches
- Known exploitation
Where a vulnerability affects a supplier service or component used by the organization:
Identify → Validate → Assess → Treat → Verify
Relevant findings should be connected to the organization’s vulnerability-management process.
15. Incident Monitoring
Suppliers should be expected to notify the organization of relevant security incidents according to contractual requirements.
Monitor:
- Security incidents
- Data breaches
- Unauthorized access
- Service compromise
- Malware/ransomware
- Supply-chain attacks
- Major vulnerabilities
- Availability incidents
- Privacy incidents
Significant incidents should trigger:
Incident Response → Supplier Reassessment → Risk Review → Corrective Action
16. Subprocessor Monitoring
Where suppliers use subprocessors, monitor:
- New subprocessors
- Changes in subprocessors
- Changes in services
- Data-access changes
- Data-location changes
- Security assurance
- Contractual protections
- Customer notification requirements
The organization should understand significant downstream dependencies where they could affect its own information-security or privacy risk.
17. Data-Location Monitoring
Monitor material changes to:
- Data storage location
- Processing location
- Backup location
- Cross-border transfers
- Data centers
- Cloud regions
Where a change affects legal, regulatory, contractual, or privacy requirements, perform an appropriate reassessment.
18. Material Change Monitoring
Suppliers should notify the organization of material changes where required by contract.
Examples include:
- Ownership changes
- Merger/acquisition
- Major technology changes
- Service changes
- Hosting changes
- Data-location changes
- Subprocessor changes
- Major security incidents
- Significant security-control changes
- Service discontinuation
- End-of-life technology
- Significant organizational changes
Material changes should be evaluated for impact on supplier risk.
19. Periodic Supplier Review
A formal supplier review should evaluate:
Supplier Profile
- Supplier
- Service
- Business owner
- Criticality
- Contract
Security
- Security controls
- Incidents
- Vulnerabilities
- Assurance
Access
- User access
- Privileged access
- Production access
Information
- Information processed
- Classification
- Customer data
- Personal data
Operations
- SLA
- Availability
- Support
- Business continuity
Changes
- Technology
- Subprocessors
- Data location
- Ownership
- Service scope
Risk
- Current risk
- New risks
- Findings
- Residual risk
20. Review Frequency
A risk-based review model may be:
| Supplier Risk | Example Review Frequency |
|---|---|
| Low | Periodic/basic review |
| Medium | Annual review |
| High | More frequent review |
| Critical | Enhanced and frequent review |
The exact frequency should be defined according to:
- Risk
- Contract
- Regulatory requirements
- Service criticality
- Information sensitivity
- Access
- Supplier performance
- Previous findings
Critical suppliers may require continuous monitoring plus formal periodic review.
21. Event-Driven Review
A supplier should be reassessed outside the normal review cycle when:
- A major security incident occurs
- A breach is reported
- Critical vulnerability affects the service
- Supplier ownership changes
- New subprocessor is introduced
- Data location changes
- Production access increases
- New sensitive information is introduced
- Business dependency increases
- SLA performance deteriorates
- Certification expires
- Supplier announces service discontinuation
- Major contractual change occurs
- Significant regulatory requirements change
22. Supplier Risk Reassessment
Following monitoring or review, determine:
Previous Risk:
Current Risk:
Reason for Change:
New Threats:
New Vulnerabilities:
Control Changes:
Residual Risk:
Treatment Required:
Risk Owner:
Possible outcomes:
- Risk unchanged
- Risk increased
- Risk decreased
- Additional controls required
- Enhanced monitoring required
- Supplier reassessment required
- Contract amendment required
- Supplier replacement/exit assessment required
23. Findings and Corrective Actions
Supplier review findings should be documented.
| Finding ID | Supplier | Finding | Risk | Action | Owner | Due Date | Status |
|---|---|---|---|---|---|---|---|
Track:
Finding → Corrective Action → Evidence → Verification → Closure
Overdue high-risk findings should be escalated according to the organization’s governance process.
24. Critical Supplier Monitoring
Critical suppliers should receive enhanced monitoring.
Review:
- Business dependency
- Customer impact
- Production access
- Privileged access
- Security incidents
- Assurance reports
- Availability
- Recovery capability
- Subprocessors
- Concentration risk
- Exit arrangements
- Material changes
- Open security findings
Critical supplier monitoring should be coordinated with:
- Critical Supplier Register
- Supplier Risk Assessment
- ICT Dependency Register
- Business Continuity Plan
25. Supplier Concentration Monitoring
Monitor whether excessive dependency develops on a supplier.
For example:
Production hosting, backup, monitoring, and disaster recovery may all depend on the same technology ecosystem.
Consider:
- Number of critical services
- Number of applications
- Number of business units
- Alternative suppliers
- Migration difficulty
- Recovery dependency
- Geographic concentration
Changes in concentration risk should trigger reassessment where appropriate.
26. Supplier Business Continuity Monitoring
For critical suppliers, review relevant:
- Business continuity plans
- Disaster recovery plans
- Recovery testing
- RTO
- RPO
- Availability commitments
- Resilience architecture
- Backup arrangements
- Alternative locations
- Recovery dependencies
The objective is to determine whether supplier continuity arrangements remain appropriate for the organization’s dependency.
27. Supplier Offboarding Trigger
Monitoring may identify circumstances requiring supplier exit consideration.
Examples:
- Unacceptable security risk
- Repeated serious control failures
- Persistent unresolved findings
- Material contractual breach
- Major security incident
- Service discontinuation
- Unacceptable concentration risk
- Loss of required certification/assurance
- Regulatory incompatibility
- Business requirement change
Any supplier termination should follow the organization’s Supplier Offboarding Checklist.
28. Monitoring Records
Maintain appropriate evidence such as:
- Supplier monitoring records
- Review reports
- Security questionnaires
- Assurance reports
- Certification records
- SLA reports
- Incident notifications
- Vulnerability notifications
- Access reviews
- Subprocessor lists
- Contract amendments
- Data-location assessments
- Risk reassessments
- Corrective-action records
- Approval records
- Meeting records
29. Supplier Monitoring Register
A centralized register may be used.
| Supplier | Criticality | Last Review | Next Review | Assurance Expiry | Incidents | Open Findings | Risk | Status |
|---|---|---|---|---|---|---|---|---|
This provides management with a consolidated view of supplier risk.
30. AWS SaaS Example
Consider a SaaS company using AWS as its primary production cloud provider.
Supplier
AWS
Services
- EC2/ECS
- RDS
- S3
- IAM
- CloudTrail
- CloudWatch
- KMS
Monitoring Areas
Security
- Security advisories
- Cloud security events
- Account activity
Access
- IAM users
- Roles
- MFA
- Privileged access
Availability
- Service health
- Production availability
- Recovery capability
Assurance
- Relevant security/compliance reports
Dependency
- Customer-facing production platform
Concentration
- Production, backup, and other services may depend on the same provider
Review Outcome
The organization should document whether:
- Security controls remain appropriate
- Access remains necessary
- Recovery arrangements remain effective
- Supplier risk has changed
- Additional treatment is required
31. Startup-Friendly Monitoring Model
A startup can implement a simple three-level model.
Level 1 — Low Risk
Monitor:
- Contract
- Service performance
- Material changes
Perform basic periodic review.
Level 2 — Medium/High Risk
Monitor:
- Security
- Access
- Assurance
- Incidents
- Vulnerabilities
- Performance
- Changes
Perform formal periodic review.
Level 3 — Critical
Monitor:
- Security
- Access
- Incidents
- Vulnerabilities
- Availability
- Assurance
- Subprocessors
- Data location
- Concentration
- Recovery
- Exit capability
Perform enhanced periodic review and event-driven reassessment.
32. Roles and Responsibilities
Supplier Owner
- Maintains supplier relationship
- Coordinates monitoring
- Tracks reviews
- Escalates supplier issues
Business Owner
- Confirms continued business need
- Evaluates service performance
- Confirms business criticality
Information Security
- Monitors security risk
- Reviews security evidence
- Assesses security incidents and vulnerabilities
Procurement
- Tracks contracts
- Supports supplier performance management
- Coordinates renewals
Legal/Privacy
- Reviews material contractual/privacy changes
- Supports regulatory assessment
Risk Owner
- Owns significant supplier risks
- Approves treatment or risk acceptance where authorized
33. Common Mistakes
Mistake 1 — Reviewing suppliers only at onboarding
Supplier risk changes over time.
Mistake 2 — Treating all suppliers identically
Monitoring should be proportional to risk.
Mistake 3 — Checking only certificates
Security assurance should be considered alongside the actual service, access, information, and dependency.
Mistake 4 — Ignoring supplier access
Access can become excessive or unnecessary over time.
Mistake 5 — Ignoring subprocessors
Downstream dependencies can materially affect supplier risk.
Mistake 6 — Not tracking assurance expiry
Expired certifications or reports should trigger appropriate review.
Mistake 7 — No event-driven reassessment
Major incidents and material changes should trigger additional review.
Mistake 8 — Failing to track findings
Identifying a supplier weakness without tracking remediation creates little risk-management value.
34. Quick Audit Checklist
| Question | Yes/No/N/A |
|---|---|
| Is supplier monitoring risk-based? | |
| Are suppliers classified by criticality? | |
| Are critical suppliers subject to enhanced monitoring? | |
| Are supplier security incidents monitored? | |
| Are supplier vulnerabilities monitored? | |
| Is supplier access periodically reviewed? | |
| Are privileged supplier accounts reviewed? | |
| Are certifications/assurance reports monitored? | |
| Are assurance expiry dates tracked? | |
| Are supplier performance/SLA metrics monitored where relevant? | |
| Are subprocessors monitored? | |
| Are data-location changes monitored? | |
| Are material supplier changes monitored? | |
| Is concentration risk reviewed? | |
| Are business continuity arrangements reviewed for critical suppliers? | |
| Are supplier findings tracked? | |
| Are high-risk findings escalated? | |
| Are event-driven reassessments performed? | |
| Is supplier risk reassessed after significant incidents? | |
| Are monitoring records retained? | |
| Are supplier offboarding triggers defined? |
35. Relationship With Other ISMS Documents
| Document | Relationship |
|---|---|
| Supplier Register | Master list of suppliers |
| Critical Supplier Register | Identifies suppliers requiring enhanced monitoring |
| Supplier Risk Assessment | Provides detailed supplier risk |
| Supply Chain Risk Assessment | Assesses broader supply-chain risk |
| Supplier Security Questionnaire | Collects supplier security information |
| Supplier Security Review | Provides formal periodic security review |
| Supplier Access Review | Reviews supplier system access |
| Supplier Contract Review | Reviews contractual requirements |
| Supplier Security Agreement | Defines supplier security obligations |
| ICT Dependency Register | Identifies technology dependencies |
| Critical Technology Dependency Assessment | Assesses critical technology dependencies |
| Supplier Offboarding Checklist | Provides secure supplier termination process |
| Risk Register | Tracks significant supplier risks |
| Incident Response Procedure | Handles supplier-related incidents |
36. ISO 27001 Connection
Supplier monitoring supports the organization’s broader information-security risk-management and supplier-management processes.
The organization should establish monitoring and review activities appropriate to:
- Supplier risk
- Information sensitivity
- System access
- Business dependency
- Security requirements
- Contractual obligations
- Legal/regulatory requirements
- Criticality of the supplied service
The policy should not be interpreted as requiring identical monitoring for every supplier. The organization’s risk assessment should determine the appropriate level of oversight.
37. Final Supplier Monitoring Lifecycle
A mature supplier-management lifecycle should demonstrate:
Supplier Selected
↓
Due Diligence Completed
↓
Risk Assessed
↓
Security Requirements Defined
↓
Contract Executed
↓
Supplier Onboarded
↓
Access Granted
↓
Supplier Monitored
↓
Periodic Review Performed
↓
Changes & Incidents Assessed
↓
Risk Reassessed
↓
Findings Treated
↓
Residual Risk Reviewed
↓
Supplier Continues / Enhanced Controls / Exit
↓
Offboarding When Required
Final Principle
Supplier management should not stop after the contract is signed.
The organization should continuously ask:
Is the supplier still providing the expected service, are the security controls still appropriate, has anything changed, and does the supplier’s current risk remain acceptable?
Effective monitoring connects supplier performance, security, access, incidents, vulnerabilities, assurance, business continuity, dependency, and risk into one lifecycle.