Third-party security questionnaires: 5 pitfalls CISOs must avoid

As a Chief Information Security Officer (CISO), managing third-party risk is a critical aspect of your role. One widely used tool for this is the third-party security questionnaire, designed to assess the security posture of vendors, suppliers, and partners. However, these tools often present challenges that can compromise their effectiveness. Based on insights from risk management experts and industry practitioners, we’ve identified five key pitfalls CISOs should avoid to optimise response rates, accuracy, and reliability. Here’s how to address them:

Pitfall 1: Overly complex questionnaires

The problem
Many security questionnaires are too long or convoluted, overwhelming vendors who often handle multiple similar requests. This can result in rushed, incomplete, or inaccurate responses—especially when dealing with open-ended questions.

The solution
Simplify your questionnaires. Focus on critical security aspects aligned with your organisation's risk management strategy. Use clear, concise language and prioritise closed questions, which are quicker to answer and yield consistent, measurable data. A streamlined questionnaire improves response quality and fosters better collaboration with your vendors.

Pitfall 2: A one-size-fits-all approach

The problem
Not all vendors pose the same risk. Applying uniform questionnaires to all third parties wastes resources and fails to account for varying risk levels. A low-risk vendor doesn’t need the same scrutiny as a critical infrastructure provider.

The solution
Tailor questionnaires based on vendor risk profiles. Develop tiered assessments that adjust for each vendor's role and potential impact on your organisation. For example, a cloud service provider might require an in-depth review, while a small supplier may only need a basic evaluation. Automated platforms can simplify this customisation, saving time while ensuring thorough risk assessment.

Pitfall 3: Assessing third parties in isolation

The problem
In many organisations, departments like compliance, procurement, sustainability, and security conduct separate third-party assessments. This fragmented approach results in redundant requests, supplier frustration, and a disjointed understanding of overall risk.

The solution
Adopt a centralised assessment process. Use shared tools or questionnaires that capture relevant data for all departments. A unified approach reduces duplication, improves supplier experience, and ensures comprehensive risk insights that account for organisational priorities.

Pitfall 4: Ignoring industry best practices

The problem
Questionnaires that don’t align with established frameworks like ISO 27001, NIST, or CIS lead to inefficiencies. Suppliers often face repetitive, inconsistent questions that are difficult to answer systematically, creating delays and unreliable data.

The solution
Leverage recognised standards. Base your questionnaires on common frameworks and reference specific controls within these standards. For example, use ISO 27001’s encryption controls instead of drafting custom questions. This approach ensures consistency, simplifies the process for suppliers, and facilitates data analysis across vendors.

Pitfall 5: Not explaining the ‘why’

The problem
Suppliers often deprioritise questionnaires when they don’t understand their significance. This can lead to delays, incomplete answers, and a lack of engagement.

The solution
Communicate the purpose of the questionnaire clearly. Explain how accurate responses contribute to mutual security and compliance. Highlight benefits like stronger partnerships and reduced risks. Use tools like explainer videos or senior leadership endorsements to emphasise the importance of timely and accurate responses.

Bonus pitfall: Sole reliance on questionnaires

The problem
Questionnaires are a critical tool, but relying on them exclusively can leave gaps in understanding a vendor’s security posture and be very time-consuming.

The solution
Complement questionnaires with real-time monitoring and additional assessment methods. Conduct on-site visits, request certifications, perform regular audits, or use security rating tools to monitor vendors continuously. A multi-layered approach provides a holistic view of third-party risk.

Conclusion

Third-party security questionnaires remain a cornerstone of effective risk management. By avoiding common pitfalls—such as overly complex forms, generic approaches, fragmented assessments, and ignoring best practices—you can improve their impact significantly. Tailored, simplified, and coordinated strategies will help you gather reliable, actionable insights and build stronger, more secure relationships with your third parties.

As a CISO, adopting these measures strengthens your organisation's defence against third-party risks, safeguarding sensitive data and ensuring operational resilience.