Supply Chain Cyber Security Guide

Protecting Your Business From Third-Party Risk

A practical guide for engineering firms, manufacturers, and CNI suppliers

Published: January 2026

Author: Dead Simple Computing Ltd

Version: 1.0

Contents

• Executive Summary
• Why Supply Chain Security Matters Now
• The 2025 Wake-Up Call: Major UK Breaches
• Understanding Supply Chain Risk
• Regulatory Requirements
• Assessing Your Supply Chain
• Managing Supplier Risk
• What Your Customers Will Require From You
• Incident Response Across The Supply Chain
• Building Supply Chain Resilience
• Supply Chain Security Checklist
• How DSC Can Help

1. Executive Summary

Supply chain cyber attacks have become the dominant threat to UK businesses. In 2025, major incidents at Marks & Spencer, Jaguar Land Rover, and the NHS demonstrated how attackers exploit trusted supplier relationships to reach their targets.

Key points:

• You are a target - Whether you're a supplier or a buyer, supply chain relationships create risk
• Regulation is coming - The Cyber Security and Resilience Bill mandates supply chain security
• Customers are demanding more - Security questionnaires, audits, and certifications are now standard
• One weak link breaks the chain - Your security is only as strong as your least secure supplier

What you need to do:

• Map your critical suppliers and understand your dependencies
• Assess supplier security postures and manage risks
• Implement security requirements in contracts
• Prepare for customer security requirements flowing down to you
• Build incident response processes that include suppliers

The opportunity:

Organisations that demonstrate strong supply chain security will win business. Those that don't will lose contracts and face regulatory scrutiny.

2. Why Supply Chain Security Matters Now

The Shift in Attacker Tactics

Attackers have learned that the front door is often well-defended. Large organisations invest heavily in security, making direct attacks difficult. But their suppliers? Often less so.

Why attackers target suppliers:

• Trusted access - Suppliers often have legitimate access to customer systems, networks, or data
• Weaker defences - SME suppliers may lack dedicated security teams or enterprise tools
• Multiplier effect - Compromise one supplier, gain access to many customers
• Trust exploitation - Emails from known suppliers bypass suspicion
• Longer dwell time - Attacks through suppliers may go undetected longer

The Interconnected Reality

Modern businesses don't operate in isolation. Consider how many third parties touch your operations:

• IT service providers (MSPs, cloud providers, software vendors)
• Professional services (accountants, lawyers, consultants)
• Logistics and delivery partners
• Component and raw material suppliers
• Contractors and temporary staff agencies
• Utilities and facilities management

Each relationship creates potential exposure. Each supplier has their own suppliers. The chain extends further than most organisations realise.

The Regulatory Response

Governments worldwide are responding with regulation:

• UK Cyber Security and Resilience Bill - Explicit supply chain security requirements, "Designated Critical Supplier" category
• EU NIS2 Directive - Supply chain security measures mandatory for essential entities
• DORA - ICT third-party risk management for financial services
• Cyber Governance Code of Practice - Boards must oversee supply chain risk

The message is clear: supply chain security is no longer optional.

3. The 2025 Wake-Up Call: Major UK Breaches

Marks & Spencer

What happened:

Attackers gained initial access through social engineering of a third-party contractor's IT service desk. The compromise went undetected, allowing ransomware deployment that disrupted online orders and Click & Collect services for months.

Impact:

• Months of operational disruption
• Customer data exposed (names, contact details, purchase history)
• ICO investigation under GDPR
• Reputational damage during peak trading periods

Lesson:

Your suppliers' help desk is your help desk. Their security failures become your security failures.

Jaguar Land Rover

What happened:

Ransomware attack brought all UK manufacturing to a halt for nearly a month. The attack exploited vulnerabilities in the complex supplier ecosystem supporting automotive production.

Impact:

• All UK factory production stopped
• 104,000 supply chain jobs at risk
• £50+ million losses per week
• Government £1.5 billion loan guarantee to stabilise sector
• Customer data stolen
• Small suppliers "pushed to the brink of collapse"

Lesson:

Supply chain attacks don't just affect the target. The ripple effects threaten entire ecosystems. Small suppliers dependent on a single customer face existential risk.

Synnovis (NHS)

What happened:

Ransomware attack on Synnovis, a pathology services provider to NHS hospitals in London. The attack disrupted blood testing and other laboratory services.

Impact:

• Surgeries cancelled across London hospitals
• Blood testing severely impacted
• Patient care directly affected
• Months to fully recover

Lesson:

Critical service providers in healthcare, CNI, and other essential sectors are high-value targets. Their compromise affects services far beyond their own organisation.

The Common Thread

All three incidents share characteristics:

• Attack came through or targeted a supplier/service provider
• Trust relationships were exploited
• Impact extended far beyond the initially compromised organisation
• Recovery took months, not days
• Smaller suppliers in the chain faced disproportionate impact

4. Understanding Supply Chain Risk

Types of Supply Chain Cyber Risk

1. Direct compromise of supplier

Attacker breaches supplier, then uses that access to reach you.

• Supplier credentials used to access your systems
• Malware deployed through supplier's legitimate access
• Data stolen from supplier that relates to your organisation

2. Compromised products or services

What you receive from the supplier is itself compromised.

• Software updates containing malware (SolarWinds-style)
• Hardware with embedded vulnerabilities
• Cloud services with security weaknesses

3. Supplier service failure

Supplier's cyber incident prevents them from serving you.

• Ransomware takes supplier offline
• Data breach forces supplier to suspend operations
• Incident response disrupts normal service delivery

4. Data exposure through supplier

Your data held by supplier is exposed.

• Supplier breach exposes your customer data
• Supplier employee accesses your data inappropriately
• Supplier's own suppliers compromise your data

5. Concentration risk

Over-dependence on single supplier creates systemic risk.

• Key supplier failure halts your operations
• No alternative supplier available
• Switching costs prohibitive

Mapping Your Exposure

To understand your supply chain risk, consider:

What access do suppliers have?

• Remote access to your network?
• Credentials to your systems?
• Physical access to your premises?
• Access to your cloud environments?

What data do suppliers hold?

• Customer personal data?
• Employee data?
• Financial information?
• Intellectual property?
• Commercially sensitive information?

What services do suppliers provide?

• Could you operate without them?
• How quickly could you replace them?
• Are there alternatives available?

What's the chain behind your suppliers?

• Who are their critical suppliers?
• Where are the hidden dependencies?
• What's their security posture?

5. Regulatory Requirements

UK Cyber Security and Resilience Bill

The Bill, currently before Parliament, introduces explicit supply chain security obligations.

For operators of essential services:

• Must assess cyber security risks from supply chain
• Must implement appropriate measures to manage those risks
• Must include security requirements in supplier contracts
• Must monitor supplier compliance

Designated Critical Suppliers:

• Regulators can designate suppliers as "critical" if their failure would significantly impact essential services
• Designated suppliers face direct regulatory obligations
• Must meet equivalent security requirements to operators

What this means:

If you supply to CNI operators (energy, transport, health, water, digital infrastructure), expect increased security scrutiny. If you're designated as critical, you'll be directly regulated.

NIS2 Directive (EU)

For organisations operating in the EU or supplying EU customers:

• Essential and important entities must address supply chain security
• Must consider vulnerabilities specific to each supplier
• Must assess overall security quality of suppliers
• Must implement security measures in contracts

Cyber Governance Code of Practice

Published April 2025, the Code requires boards to:

• Gain assurance that the organisation is resilient to supply chain cyber risks
• Ensure supply chain security is part of risk management
• Include supply chain in incident response planning

Defence Sector Requirements

For defence supply chain:

• Cyber Essentials Plus - Often mandatory for contracts
• DEFCON 658 - Flow-down of security requirements
• Defence Standard 05-138 - Cyber security for defence suppliers
• UK data residency - Requirements for handling controlled information

Sector-Specific Requirements

Different sectors have additional requirements:

6. Assessing Your Supply Chain

Step 1: Identify Your Suppliers

Create a comprehensive supplier inventory:

Categories to include:

• IT service providers (MSPs, cloud, software, hardware)
• Professional services (legal, accounting, consulting)
• Operational suppliers (logistics, facilities, utilities)
• Component and material suppliers
• Contractors and agencies
• Any organisation with access to your systems or data

For each supplier, document:

• What service/product they provide
• What access they have (systems, data, premises)
• What data they hold or process
• How critical they are to your operations
• Contract details and security terms

Step 2: Categorise by Risk

Not all suppliers present equal risk. Prioritise based on:

Criticality:

• High: Operations would stop without them
• Medium: Significant impact but alternatives exist
• Low: Minimal operational impact

Access:

• High: Direct access to systems/network/sensitive data
• Medium: Limited access, some data exposure
• Low: No system access, minimal data

Data sensitivity:

• High: Personal data, IP, financial, customer data
• Medium: Internal business data
• Low: No sensitive data

Combined risk rating:

Focus your efforts on high-criticality, high-access, high-sensitivity suppliers first.

Step 3: Assess Supplier Security

For prioritised suppliers, assess their security posture:

Certifications and accreditations:

• ISO 27001 certified?
• Cyber Essentials / CE+ certified?
• SOC 2 report available?
• Sector-specific accreditations?

Security questionnaire:

Send a structured questionnaire covering:

• Governance and policies
• Access control
• Data protection
• Incident response
• Business continuity
• Sub-contractor management

Evidence review:

Request evidence of:

• Security policies
• Penetration test results (summary)
• Incident history
• Insurance coverage

Site visits / audits:

For critical suppliers, consider:

• On-site security assessment
• Technical audit
• Process review

Step 4: Identify Gaps and Risks

Compare supplier security against your requirements:

• Where do suppliers fall short?
• What risks does this create?
• Can gaps be remediated?
• Should you accept, mitigate, or avoid the risk?

Step 5: Document and Monitor

Maintain records of:

• Supplier risk assessments
• Identified gaps and remediation plans
• Ongoing monitoring activities
• Review dates and outcomes

7. Managing Supplier Risk

Contractual Controls

Build security into supplier contracts:

Security requirements:

• Minimum security standards (e.g., CE+, ISO 27001)
• Specific controls required
• Compliance with your policies
• Right to audit
• Sub-contractor approval

Incident notification:

• Obligation to notify you of security incidents
• Timeframe for notification (e.g., 24 hours)
• Information to be provided
• Cooperation with your incident response

Data protection:

• Data handling requirements
• Encryption standards
• Access controls
• Deletion/return on termination

Liability and insurance:

• Cyber insurance requirements
• Liability for breaches
• Indemnification

Termination:

• Right to terminate for security failures
• Transition assistance
• Data return/deletion

Ongoing Monitoring

Security assessment is not one-time:

Regular reviews:

• Annual security questionnaire
• Certification renewal verification
• Contract compliance review

Continuous monitoring:

• Security ratings services (if budget allows)
• News monitoring for supplier incidents
• Industry threat intelligence

Trigger-based reviews:

• Supplier reports a security incident
• Significant change in supplier's business
• New threats emerge affecting supplier's sector
• Contract renewal

Remediation and Improvement

When gaps are identified:

Collaborative approach:

• Work with suppliers to improve security
• Provide guidance and support
• Set realistic timelines for remediation

Escalation:

• Clear escalation path for non-compliance
• Senior stakeholder involvement
• Business relationship consequences

Alternative planning:

• Identify alternative suppliers
• Reduce dependency where possible
• Plan for supplier failure

8. What Your Customers Will Require From You

If you're a supplier to larger organisations or regulated entities, expect increasing security requirements.

Security Questionnaires

Common questionnaire frameworks:

• Standardised Information Gathering (SIG) questionnaire
• CAIQ (Cloud Security Alliance)
• Customer-specific questionnaires
• Sector-specific questionnaires (e.g., airport security)

Topics typically covered:

• Information security governance
• Risk management
• Access control
• Data protection
• Encryption
• Network security
• Incident response
• Business continuity
• Physical security
• Personnel security
• Third-party management

How to prepare:

• Maintain a master response document
• Keep evidence readily available
• Review and update regularly
• Be honest about gaps

Certification Requirements

Commonly requested:

Choosing what to pursue:

• Check customer requirements
• Consider sector expectations
• Start with CE, progress to CE+, then ISO 27001

Audits and Assessments

What customers may request:

• Desktop review of policies and evidence
• Remote assessment via questionnaire and calls
• On-site audit of premises and controls
• Penetration test results or scope inclusion

How to prepare:

• Document your security measures
• Maintain evidence of compliance
• Be audit-ready at all times
• Designate audit liaison

Contractual Obligations

Expect contracts to include:

• Security standards you must meet
• Incident notification requirements
• Data handling obligations
• Audit rights
• Liability provisions
• Insurance requirements

Negotiate reasonably:

• Understand what you can commit to
• Be realistic about your capabilities
• Seek clarity on requirements
• Push back on unreasonable demands

Incident Notification

You will likely need to:

• Notify customers within short timeframes (24-48 hours)
• Provide specific information about incidents
• Cooperate with customer incident response
• Provide ongoing updates
• Conduct root cause analysis

9. Incident Response Across The Supply Chain

When Your Supplier Has An Incident

Immediate actions:

• Determine if you're affected
• Assess potential exposure (data, access, systems)
• Implement containment measures (revoke access, isolate systems)
• Engage your incident response process
• Communicate with stakeholders

Ongoing response:

• Maintain contact with supplier for updates
• Assess actual vs potential impact
• Determine notification obligations (regulator, customers)
• Document all actions and decisions
• Conduct post-incident review

Questions for your supplier:

• What happened and when?
• What systems/data were affected?
• Was our data/access involved?
• What containment actions have been taken?
• What is the timeline for recovery?
• What forensic investigation is underway?

When You Have An Incident

Customer notification:

• Review contractual notification obligations
• Notify affected customers within required timeframes
• Provide factual information about what happened
• Explain what you're doing about it
• Commit to updates

Coordinated response:

• Customers may want to be involved in response
• Share relevant information while protecting investigation
• Align on external communications
• Conduct joint lessons learned

Building Supply Chain Incident Response

Include suppliers in your planning:

• Document supplier contacts for incident response
• Include key suppliers in tabletop exercises
• Test notification processes
• Review and update contact information regularly

Include supply chain in your plans:

• Scenarios involving supplier compromise
• Containment actions for supplier incidents
• Communication templates for customers
• Alternative supplier activation

10. Building Supply Chain Resilience

Reduce Dependency

Avoid single points of failure:

• Identify critical single-source suppliers
• Develop alternative supplier relationships
• Maintain capability to switch if needed
• Consider in-house alternatives for critical functions

Distribute risk:

• Spread work across multiple suppliers where practical
• Avoid concentration in single geographies
• Maintain relationships with backup suppliers

Secure by Design

Build security into procurement:

• Include security in supplier selection criteria
• Weight security appropriately in evaluations
• Don't just select on price
• Assess security before contracting

Secure integration:

• Minimise supplier access to what's necessary
• Segment supplier access from critical systems
• Monitor supplier activity
• Review access regularly

Continuous Improvement

Learn from incidents:

• Review all supplier security incidents
• Apply lessons across supplier base
• Update requirements and assessments

Stay current:

• Monitor evolving threats
• Update supplier requirements
• Refresh assessments for high-risk suppliers
• Track regulatory changes

Culture and Awareness

Internal awareness:

• Staff understand supply chain risks
• Procurement trained on security requirements
• Business owners engaged in supplier security

Supplier engagement:

• Share threat intelligence with key suppliers
• Collaborative approach to security improvement
• Regular security discussions

11. Supply Chain Security Checklist

Governance

• ☐ Board oversight of supply chain security
• ☐ Supply chain security policy in place
• ☐ Roles and responsibilities defined
• ☐ Regular reporting on supply chain risk

Supplier Inventory

• ☐ Complete inventory of suppliers
• ☐ Access and data documented for each supplier
• ☐ Criticality ratings assigned
• ☐ Regular review and updates

Risk Assessment

• ☐ Risk assessment methodology defined
• ☐ High-risk suppliers identified
• ☐ Assessments conducted for prioritised suppliers
• ☐ Gaps and risks documented

Contracts

• ☐ Security requirements in contracts
• ☐ Incident notification clauses
• ☐ Audit rights included
• ☐ Sub-contractor provisions
• ☐ Termination rights for security failures

Ongoing Management

• ☐ Regular supplier reviews scheduled
• ☐ Certification expiry tracking
• ☐ Monitoring process in place
• ☐ Remediation tracking

Incident Response

• ☐ Supplier incident response plan
• ☐ Supplier contact list maintained
• ☐ Notification templates prepared
• ☐ Tabletop exercises include suppliers

Your Own Security

• ☐ Certifications current (CE+, ISO 27001)
• ☐ Security questionnaire responses ready
• ☐ Evidence documentation maintained
• ☐ Incident notification process defined

12. How DSC Can Help

Dead Simple Computing helps organisations manage supply chain cyber risk - whether you need to assess your suppliers or demonstrate your security to customers.

Supply Chain Assessment

Supplier Risk Assessment

• Map your critical suppliers
• Assess supplier security postures
• Identify gaps and risks
• Prioritise remediation

Security Questionnaire Support

• Review and score supplier responses
• Identify red flags and gaps
• Recommend follow-up actions

Helping You Meet Customer Requirements

Certification Support

• Cyber Essentials and CE+ certification
• ISO 27001 implementation
• Ongoing compliance management

Questionnaire Response

• Help preparing responses
• Evidence documentation
• Audit preparation

Security Services

Managed Security

• 24/7 MDR monitoring
• UK-based SIEM
• Vulnerability management
• Security that meets customer requirements

Compliance-Ready IT

• Managed IT with security built in
• Evidence and reporting as standard
• Audit-ready documentation

Advisory

vCISO Services

• Strategic supply chain security oversight
• Policy development
• Customer questionnaire support
• Board reporting

Incident Response Planning

• Supply chain incident response
• Playbooks and procedures
• Tabletop exercises

Further Resources

Official Sources

• NCSC Supply Chain Security Guidance: ncsc.gov.uk
• Cyber Security and Resilience Bill: parliament.uk
• Cyber Governance Code of Practice: gov.uk

DSC Resources

• Website: deadsimplecomputing.co.uk
• Contact: [email protected]
• Phone: 0118 359 2220

About This Guide

This guide was prepared by Dead Simple Computing Ltd in January 2026 to help organisations understand and manage supply chain cyber security risks.

This guide is for informational purposes and does not constitute legal advice. Organisations should seek appropriate professional advice for their specific circumstances.

About Dead Simple Computing

Dead Simple Computing is an MSP/MSSP providing managed IT, security services, and compliance support for regulated industries.

Credentials:

• CISSP certified
• ISO 27001 certified
• Cyber Essentials Plus certified

Contact us:

• Web: deadsimplecomputing.co.uk
• Email: [email protected]
• Phone: 0118 359 2220

© 2026 Dead Simple Computing Ltd. All rights reserved.