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Could one of your suppliers be the weakest link in your cyber security?

Written by Rachael McKenzie | Sep 29, 2026, 7:30:00 AM

You might have strong passwords, well-managed devices, updated systems and a team that knows how to recognise a suspicious email. But what about the businesses you rely on every day?

Modern SMEs are connected to an extensive network of software providers, cloud platforms, accountants, payroll companies, HR specialists, marketing agencies, resellers, contractors and other external partners. Those relationships make it possible to work efficiently, but every new connection can also create another route into your data or systems.

That is why supply chain security is no longer something only large companies need to think about. If a trusted supplier holds your data, connects to your systems or supports a service you depend on, its security can quickly become your security.

What is a supply chain cyber attack?

A supply chain attack happens when a cyber criminal targets a weakness somewhere in the network of businesses involved in delivering a product or service. The initial target might not be your business. It could be a software vendor, booking system, payment provider or another trusted partner. Once that supplier is compromised, the attacker may be able to reach the supplier's customers, access information held on their behalf or use an established relationship to make a malicious communication appear legitimate.

Why supply chain security matters more than ever for SMEs

Many SME leaders assume cyber security begins and ends with their own business. In reality, your cyber security is only as strong as the suppliers, software providers and third-party partners you trust every day.

Whether it's a cloud application, payroll platform, IT vendor, accountant, marketing agency or business software provider, external organisations have access to sensitive data, business systems or critical processes. If one of those suppliers experiences a cyber attack, data breach or security failure, your business could feel the impact too.

This is why supply chain security has become one of the fastest-growing concerns for SMEs. Cyber criminals increasingly target trusted third parties because they often provide a pathway into multiple businesses through a single compromise.

The lesson isn't that businesses should avoid working with external suppliers. Modern businesses rely heavily on specialist partners, cloud services and outsourced expertise. They key is ensuring every important supplier relationship is understood, managed and reviewed as part of your wider cyber security strategy.

Why can a trusted supplier still create a cyber security risk?

Working with reputable suppliers is important, but trust alone doesn't eliminate risk. Many suppliers process confidential business information, manage customer data, store employee records or connect directly to core business systems. In some cases, suppliers may also rely on their own third-party partners and subcontractors, creating additional layers of complexity that are often invisible to customers.

As supplier ecosystems grow, it becomes increasingly difficult to understand:

  • Where data is being stored
  • Who has access to sensitive information
  • Which systems are connected together
  • How potential incidents would be reported
  • What would happen if a supplier became unavailable

A good starting point for assessing supplier cyber risk is to ask:

  • What business or customer information does this supplier hold?
  • Does the supplier have access to our systems, networks or data?
  • Is that access restricted to what they genuinely need?
  • Who internally owns and manages the supplier relationship?
  • How would the supplier notify us of a cyber security incident?
  • What would happen if the supplier's services were unavailable tomorrow?

These questions aren't designed to challenge trusted suppliers. They create clarity, establish accountability and help reduce security assumptions that could become vulnerabilities later.

What is Shadow IT?

One of the biggest threats to supply chain security is something many businesses don't even realise they have.

Shadow IT refers to any software application, device, cloud service or technology used without formal approval from the people responsible for IT and cyber security.

It usually begins with good intentions.

An employee discovers a faster way to share files. A department adopts a new productivity tool. A supplier suggests using an alternative collaboration platform. A contractor introduces a different communication app to speed up a project. The technology may appear harmless, but it often bypasses established security controls, governance processes and supplier risk assessments. 

As a result, businesses may have no visibility of:

  • Where data is stored
  • Who can access it
  • Whether security updates are being applied
  • how incidents would be detected
  • Whether regulatory requirements are being met

If nobody knows a tool exists, nobody can secure it

This is what makes Shadow IT so dangerous. When applications are introduced without approval, security teams can't properly assess or monitor them. A single unauthorised platform can create an unexpected route into sensitive data, customer information or business systems. Simply telling employees not to use not to use unauthorised technology rarely solves the problem.

Instead, businesses should ensure approved tools are clearly communicated, easily accessible and supported by simple processes for requesting alternatives when genuine business needs arise.

Importantly, these expectations should extend beyond employees. Suppliers, contractors and partners should understand which platforms are approved and how business information should be shared securely.

Where should businesses look for hidden third-party cyber risk?

Software vendors and cloud providers

Many software vendors host business-critical information, customer records and operational data. Businesses should understand what information is being stored, who can access it and how security responsibilities are managed throughout the supplier relationship.

Distributors and business partners

Distributors, channel partners and resellers often access shared portals, product information and customer data. Every access point should have a clear business purpose, appropriate permissions and documented security expectations.

Customer support and service teams

Employees working closely with customers regularly exchange documents, provide remote assistance and access sensitive information. Secure processes for file sharing, identity verification and system access should be straightforward and consistently followed.

Specialist service providers

HR providers, payroll companies, legal firms, finance specialists and marketing agencies often handle commercially sensitive information. Businesses should understand what data these providers hold, why they need it and what happens when contracts or relationships come to an end.

How to reduce supply chain cyber risk

Effective supply chain security doesn't require dozens of complicated policies. In most cases, a small number of clear controls can dramatically reduce risk.

1. Maintain an approved technology list

Employees, contractors and suppliers should know which applications and services are approved for business use. 

2. Identify critical suppliers

Create a record of suppliers that hold sensitive data, support critical operations or connect directly to business systems. Assign ownership internally and regularly review associated risks.

3. Define minimum security standards

Security discussions should happen before access or data sharing begins. Expectations around confidentiality, access controls, incident reporting, data protection and offboarding should be agreed from the outset.

4. Provide security awareness training

Employees and external partners should understand the risks associated with unapproved applications, shared credentials, phishing attacks and poor data handling practices. Just as importantly, they should know how to report concerns quickly.

5. Regularly review access and supplier relationships

Businesses change. Employees move roles, contracts evolve and new software is introduced. Regular reviews help identify unnecessary access, legacy systems and emerging supply chain risks before they become serious security risks.

Could your business respond to a supplier security incident?

Imagine receiving a call tomorrow advising that one of your suppliers has suffered a cyber attack.

Would you know:

  • What information they hold?
  • Which systems are connected?
  • Who should lead the response?
  • What customers need to be informed?
  • Whether business operations could continue?

Many SMEs struggle to answer these questions immediately. That doesn't mean your business is failing. It simply highlights where greater visibility and supplier governance could significantly strengthen your cyber resilience. Supply chain security is ultimately about understanding trust. Businesses don't need to eliminate supplier relationships. They need to understand which relationships matter, what risks they create and how those risks are being managed.

Could hidden supplier risks be putting your business at risk?

As cyber threats continue to evolve, understanding third-party cyber risk is becoming a critical part of protecting your business, customers and reputation. At Apex, we help SMEs review cyber security controls and build practical security strategies that support long-term business resilience.

Download your free guide today or book a complimentary Cyber Security and Supply Chain Review with one of our IT experts here.