Supplier cybersecurity audit: how to protect your company against external risks

The spread of digital supply chains is forcing companies to pay particular attention to the cybersecurity of their suppliers. Threats do not stop at internal infrastructure alone. Relationships with third parties, partners and subcontractors can pose unsuspected threats if they are not properly managed. This article will guide you through the steps of an effective audit and the best practices for securing your organisation against external risks.

To industrialise this approach, third-party assessment software centralises the analysis, monitoring and compliance of your suppliers.

What is a supplier cybersecurity audit?

A supplier cybersecurity audit consists of assessing the security level of your external partners’ systems and practices. The purpose of this audit is to check whether their security policies meet the standards and regulations in force, such as GDPR and ISO 27001, as well as more recent regulations like DORA (Digital Operational Resilience Act) and NIS 2 (Network and Information Security Directive 2). These regulatory frameworks aim to strengthen the digital resilience of companies and their ecosystems by requiring robust security of information systems and third parties.

Why is this so crucial? Because a poorly secured supplier can become an entry point for cyberattacks, such as ransomware, which can compromise the security of your systems. The audit makes it possible to identify vulnerabilities in their infrastructure and to take the actions needed to strengthen the protection of your data.

Why is a supplier cybersecurity audit essential for your company?

Identifying third-party risks

Suppliers may have access to critical information or essential systems in your company. Without a rigorous assessment of their security posture, you risk exposing your own infrastructure to attacks. The audit makes it possible to identify:

• Security flaws within suppliers’ systems.
• Poor practices in data protection.
• The level of compliance with regulations (GDPR, DORA, NIS 2, etc.).

Strengthening trust with your partners

Auditing your partners regularly helps strengthen mutual trust. When your suppliers demonstrate their cybersecurity maturity, they play an active part in securing your own environment. This helps build a relationship based on transparency and security, a significant competitive advantage in many sectors of activity.

Reducing the costs of cybersecurity incidents

A regular audit reduces the potential costs of a cyberattack coming from a vulnerable supplier. Incidents such as data breaches or intrusions into critical systems can cost millions of euros, not to mention the loss of reputation. By anticipating these risks, you limit the financial consequences.

How do you carry out an effective cybersecurity audit of your suppliers?

Step 1: Risk assessment

The first step of an audit consists of assessing the risks inherent to each supplier. Not all third parties present the same level of threat. For example, a supplier with access to critical data or production systems will carry a higher risk than a mere service provider unrelated to your core business. The aim is to prioritise suppliers according to their criticality. Here are a few key criteria for this assessment:

• The size of the supplier’s company: large companies may have teams dedicated to cybersecurity, while smaller ones may not have the resources needed to ensure a high level of security.
• The level of connection with your internal systems: a supplier with access to your network or to critical systems represents an increased risk. It is essential to understand the extent of the connections between your infrastructure and the supplier’s.
• The security track record: a supplier that has already suffered a data breach or a recent cyberattack must be examined in depth. This makes it possible to detect weaknesses in their security practices.

The risk assessment must include an analysis of each supplier’s cyber maturity, that is to say their ability to respond to threats and to comply with regulations (GDPR, DORA, NIS 2, ISO 27001). An in-depth assessment allows you to classify your suppliers by risk level and to organise your audits accordingly.

Step 2: Analysis of security processes and systems

Once the high-risk suppliers have been identified, it is important to carry out a detailed analysis of their security processes and systems. This step includes reviewing their information security policies (ISSP) as well as the specific measures they have put in place to protect data. Here are the main elements to check:

• Security policies: does the supplier have written policies covering critical areas, such as access management, the protection of sensitive data, network security and the prevention of cyberattacks?
• Employee training: are the supplier’s employees trained in cybersecurity best practices? Human error is one of the main causes of security incidents.
• Data protection: make sure that the supplier complies with data protection regulations, such as GDPR. This includes the use of encryption and the management of data access rights.
• Compliance with standards: does the supplier follow good security practices, such as those defined by ISO 27001 or NIST, or the specific requirements of DORA and NIS 2?

This analysis makes it possible to determine whether the supplier’s security practices are in line with your organisation’s expectations and with regulatory requirements.

Step 3: Penetration tests and technical assessment

To assess how robust suppliers’ infrastructure and systems are against cyber threats, it is essential to carry out penetration tests, or pentests. These tests simulate an attack and uncover the potential security flaws that could be exploited by cybercriminals. There are several types of penetration test:

• Black-box tests: the auditor has no prior information about the system being audited. This simulates an external attack, in which the attacker has no access to the supplier’s internal information.
• Grey-box tests: the auditor has partial knowledge of the systems. This approach makes it possible to test more realistic scenarios, in which the attacker could have access to certain internal information.
• White-box tests: the auditor has all the information about the system. This type of test is used to examine the supplier’s architecture and security systems in depth.

Depending on the type of penetration test chosen, the auditor will try to identify flaws in networks, applications or access systems. For example, a network penetration test could reveal vulnerabilities in firewalls or poorly secured network configurations. An application test, for its part, could identify weaknesses in the applications used by the supplier, such as vulnerabilities in the source code.

These tests make it possible to assess how well systems withstand real attacks and to propose recommendations for strengthening security.

Step 4: Continuous monitoring

The audit must not be a one-off event, because risks are constantly evolving. To guarantee an optimal level of security, it is essential to put continuous monitoring in place. This involves using monitoring and risk management tools to follow suppliers’ security practices in real time.

A few best practices for ensuring continuous monitoring:

• Implementing automatic tracking tools: tools such as SaaS risk management solutions make it possible to monitor suppliers’ cybersecurity performance on an ongoing basis. These tools offer real-time visibility of potential vulnerabilities.
• Monitoring corrective actions: if the audit reveals security flaws, it is important to make sure that the supplier implements corrective actions. Continuous monitoring allows you to track these actions and check that they have been applied correctly.
• Regularly updating audits: cybersecurity is a constantly evolving field. It is therefore recommended to reassess your suppliers regularly, in line with new threats and regulatory changes. How often audits recur will depend on the level of risk and the type of services provided.

By putting continuous monitoring in place, you make sure that potential vulnerabilities are quickly detected and corrected, thus guaranteeing your organisation’s security against third-party risks.

What are the best practices for auditing your suppliers effectively?

Setting clear and standardised audit criteria

For a cybersecurity audit to be effective, it is essential to define standardised assessment criteria based on recognised frameworks. Using frameworks such as ISO 27001, NIST or the recommendations of ANSSI (Agence nationale de la sécurité des systèmes d’information, the French national cybersecurity agency) makes it possible to structure the audit around proven best practices. Here are a few key areas to cover:

• Identity and access management: suppliers must have put rigorous controls in place to manage who has access to what within their systems.
• Data protection: the supplier must demonstrate its ability to secure sensitive data, to use encryption and to manage access to critical information.
• Threat monitoring and detection: the audit must check that the supplier has monitoring solutions capable of rapidly detecting any suspicious activity.
• Regulatory compliance: make sure that the supplier complies with the applicable regulations, such as GDPR, DORA or NIS 2, and that it follows cybersecurity best practices.

Strengthening collaboration with your suppliers

A cybersecurity audit must not be seen as a mere external inspection, but as active collaboration with your partners to improve the security of the entire supply chain. Here are a few practices for establishing effective collaboration:

• Create a common cybersecurity charter: this charter clearly defines the responsibilities of each party for protecting systems and data.
• Encourage transparency: encourage your suppliers to share their security practices regularly and to inform you of any incident or risk detected.
• Train suppliers: in some cases, it can be useful to organise training sessions to help them improve their security posture and meet your company’s expectations.

Integrating the audit into overall risk management

Supplier audits must not be isolated, but must form an integral part of your risk management strategy. By integrating the results of these audits into your overall risk management programme, you will be better able to anticipate and manage potential threats. Here are a few key points for achieving this:

• Prioritise risks: based on the audit results, identify the suppliers that carry the most risk and put action plans in place to reduce those risks.
• Implement corrective measures: if flaws are detected, it is important to work with your suppliers to correct these vulnerabilities as quickly as possible.
• Regular risk monitoring: integrate the information from the audits into your risk management dashboard, so as to follow the evolution of threats and corrective actions.

Tools and technologies for automating supplier cybersecurity audits

Auditing suppliers manually can prove complex and time-consuming, especially if you work with a large number of partners. Fortunately, technology solutions exist to automate all or part of the audit process and help you follow the security of your ecosystem in real time. Here are some of the main options available:

Automated third-party risk management

Third-party risk management solutions allow you to automate the assessment of suppliers against predefined security criteria. These platforms centralise information about your partners and assign risk scores according to their compliance with cybersecurity standards and the regulations in force. Here are a few key features:

• Automated assessment: the tools make it possible to analyse suppliers’ security practices continuously, based on public data, previous audits and information shared by the supplier.
• Real-time dashboards: you can see at a glance the risk level of each supplier and quickly identify those that require particular attention.
• Automatic alerts: these platforms can generate alerts when a supplier’s security score drops or when a new vulnerability is detected.

Monitoring corrective actions

Once vulnerabilities have been identified, it is essential to make sure that your suppliers take the measures needed to remedy them. Corrective action tracking tools allow you to monitor the implementation of measures and ensure rigorous follow-up. Here is how these tools can help you:

• Real-time tracking: the corrective actions taken by your suppliers are tracked in real time, allowing you to check whether they are being implemented correctly.
• Progress reports: these tools automatically generate reports on the progress of the corrections made, making communication with internal stakeholders easier.
• Post-action assessment: once the corrective actions have been put in place, you can carry out a new assessment to check the effectiveness of the measures applied.

Generating customised reports

Automated audit solutions also make it possible to generate customised reports that can be adapted to your specific needs. This makes it easier to share information with senior management, compliance teams and other stakeholders. Here is what these reports can include:

• Overall supplier security score: an overview of each supplier’s level of cyber risk, based on objective criteria.
• Details of vulnerabilities: a summary of the security flaws identified and the corrective actions recommended.
• Compliance monitoring: the report can indicate whether the supplier complies with regulatory requirements such as GDPR, DORA, NIS 2 or ISO standards.

Integration with your SaaS solution

Many companies are adopting SaaS solutions to automate and centralise cybersecurity management. If you already use a SaaS platform to steer your security and compliance activities, it is important that it can integrate with your supplier audit tools. Such integration makes it possible to:

• Centralise risk management: all the information about your suppliers is centralised in a single tool, which simplifies day-to-day management.
• Automate regular audits: the SaaS solution can plan and automatically carry out periodic audits, ensuring regular monitoring of suppliers’ security.
• Make communication easier: the reports and alerts generated by your SaaS solution can be shared with internal stakeholders, thus ensuring complete transparency on the state of third-party security.

A supplier cybersecurity audit is an indispensable step for any organisation that cares about protecting its systems and data. By anticipating the risks linked to your third parties, you strengthen not only your own security posture, but also that of your entire digital ecosystem.

By carrying out regular audits, you identify potential flaws and put corrective actions in place before they become exploitable vulnerabilities. Whether through process assessments, penetration tests or the implementation of continuous monitoring, each step brings you closer to stronger cybersecurity.

In addition, automating the audit process with suitable SaaS solutions allows you to become more efficient while reducing risks. You can then concentrate on what matters most: guaranteeing the security of your infrastructure and that of your customers.

For a modern company subject to increasingly strict regulations such as GDPR, DORA and NIS 2, auditing suppliers is no longer an option but a strategic necessity. Do not let security flaws at your partners become entry points for cyberattacks.

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