ISO 27001 Controls for Third-Party Supplier Risk
ISO 27001 can help organisations manage the information security risks created by cloud providers, software platforms, outsourced service providers, and other suppliers.
Third parties may store personal information, access internal systems, process financial records, or provide services that support essential operations. A supplier security failure can therefore affect confidentiality, system availability, regulatory compliance, and business continuity.
Organisations need a structured process for assessing suppliers before appointment, defining security responsibilities, controlling access, and monitoring performance throughout the relationship.
Why Third-Party Supplier Risk Matters
A third-party supplier becomes an information security risk when it can access, process, transmit, or store organisational information.
Examples may include:
- Cloud hosting providers
- Payroll and human resources platforms
- Customer relationship management systems
- External information technology support
- Software developers
- Marketing and email platforms
- Data backup providers
- Payment and financial service providers
The organisation remains responsible for understanding the risks associated with these services. A supplier’s reputation, size, or previous experience does not remove the need for proper due diligence.
Use ISO 27001 to Assess Suppliers
ISO/IEC 27001:2022 enables organisations to establish an Information Security Management System and apply a risk management process that reflects their size, operations, and information security needs.
Before appointing a supplier, the organisation should assess:
- The information and systems the supplier will access
- The sensitivity of the information involved
- Where the information will be stored
- Who will be authorised to access it
- Which subcontractors may be involved
- How access will be authenticated
- How security incidents will be reported
- How data will be backed up and recovered
- How information will be returned or deleted
The depth of the assessment should be based on risk. A supplier with access to sensitive customer information will require greater scrutiny than a provider with no access to internal systems or data.
Establish Written Security Requirements
Security responsibilities should be recorded in contracts, service-level agreements, or operator agreements.
These documents should address:
- Confidentiality and non-disclosure
- Access control requirements
- Security incident reporting
- Subcontractor management
- Data storage locations
- Backup and recovery responsibilities
- Service availability
- Audit and assurance rights
- Information retention and deletion
- Contract termination
Section 21 of POPIA requires a responsible party to use a written contract to ensure that an operator establishes and maintains appropriate security measures when processing personal information on its behalf.
A contract is not a replacement for monitoring. The organisation should confirm that the supplier is meeting its agreed-upon responsibilities.
Control Supplier Access
Suppliers should only receive the access required to perform their approved duties.
Effective access controls may include:
- Named user accounts
- Multi-factor authentication
- Restricted administrator privileges
- Time-limited access
- Approval before access is granted
- Logging and monitoring
- Regular access reviews
- Immediate removal when access is no longer required
Shared accounts should be avoided because they make it difficult to determine who completed a specific action.
The organisation should also maintain records showing who approved supplier access, when it was granted, and when it was reviewed or removed.
Monitor Suppliers Throughout the Relationship
Supplier assessments should not be completed once and forgotten.
ISO/IEC 27036-2:2022 covers the implementation, operation, monitoring, review, maintenance, and improvement of information security within supplier and acquirer relationships. Its scope includes software, hardware, business services, and cloud computing.
Ongoing monitoring may include:
- Reviewing service performance
- Confirming security certification
- Assessing audit reports
- Reviewing incidents and service disruptions
- Checking changes to subcontractors
- Monitoring unresolved corrective actions
- Reviewing access permissions
- Confirming backup and recovery testing
High-risk suppliers may require more frequent reviews than suppliers with limited access to information.
Prepare for Supplier Security Incidents
The organisation should define what suppliers must do when an incident occurs.
Incident requirements should explain:
- How quickly the supplier must report the incident
- Who must receive the notification
- What information must be provided
- How evidence must be preserved
- Who will communicate with affected parties
- How containment and recovery will be coordinated
- How corrective actions will be tracked
These requirements should be tested where possible. A supplier contact list that has not been updated may cause unnecessary delays during an actual incident.
Manage the End of the Contract
Supplier risk does not end when the service agreement expires.
The organisation should confirm that:
- System access has been removed
- Organisational equipment has been returned
- Information has been transferred securely
- Retained copies have been deleted
- Subcontractors have followed the same requirements
- Confidentiality obligations remain in effect
- Evidence of deletion has been received
A documented exit process reduces the risk of former suppliers retaining access or information that they no longer require.
Strengthen Third-Party Security with ISO 27001
Third-party services can improve efficiency, capacity, and access to specialist expertise. However, they must be supported by risk assessments, written requirements, controlled access, regular monitoring, and secure termination processes.
WWISE assists organisations with ISO 27001 implementation, supplier risk assessments, internal audits, information security policies, and certification readiness. A structured supplier management process can help your organisation protect information while maintaining reliable external relationships.
