5 Common Penetration Testing Mistakes and How to Avoid Them

Penetration testing (or “pen testing”) plays a critical role in modern cybersecurity. It helps organisations identify vulnerabilities before malicious actors can exploit them. However, not all penetration tests deliver the value they should—and in many cases, it’s due to preventable mistakes made during the planning, execution, or reporting phases.

Here are five common penetration testing mistakes, and practical ways your organisation can avoid them.

1. Failing to Define Clear Objectives

The mistake:
Many organisations jump into a pen test without a clearly defined scope or set of goals. Without this, the test may lack direction, overlook critical assets, or fail to align with the organisation’s risk profile.

How to avoid it:
Start with a discussion between stakeholders, IT, and the pen testing team to define what you’re trying to achieve. Are you testing your external perimeter? Web apps? Employee awareness through phishing simulations? Clear objectives help focus the test and deliver meaningful results.

2. Testing Only at Surface Level

The mistake:
Some tests barely scratch the surface, focusing only on basic vulnerabilities or relying solely on automated tools. This results in a false sense of security.

How to avoid it:
Ensure your penetration testers go beyond automated scans. Manual testing, business logic exploitation, privilege escalation checks, and chained attack scenarios are essential for a realistic assessment of your defences.

3. Ignoring Social Engineering

The mistake:
Neglecting social engineering is a missed opportunity. Humans are often the weakest link in security, yet many pen tests ignore phishing, vishing (voice phishing), or physical intrusion attempts.

How to avoid it:
Include a social engineering component in your test where appropriate. Test employee responses to suspicious emails or unauthorised attempts to gain physical access. Just be sure to establish boundaries and get the necessary permissions in writing beforehand.

4. Lack of Communication During the Test

The mistake:
Penetration testing isn’t just a “set it and forget it” activity. Poor communication can result in misunderstandings, missed test windows, or even unintentional disruptions to business operations.

How to avoid it:
Maintain open channels of communication between your internal teams and the testers. Use kick-off meetings, daily check-ins, and post-test debriefs to stay aligned and aware of progress, especially during red or purple team engagements.

5. Not Acting on the Findings

The mistake:
Perhaps the most damaging mistake of all is conducting a pen test, receiving the report—and then doing nothing with it. Unaddressed vulnerabilities can remain open doors for months (or longer), defeating the purpose of the test entirely.

How to avoid it:
Treat the test report as a roadmap. Prioritise high-severity findings, assign remediation tasks, and retest where necessary. Penetration testing should be part of an ongoing security improvement cycle, not a one-off checkbox exercise.

Final Thoughts

Penetration testing is only as valuable as the preparation and response that surround it. By avoiding these common mistakes, your organisation can extract maximum value from every test—turning insights into action, and vulnerabilities into hardened defences.

A Security Review is a more in-depth and comprehensive option than traditional penetration testing, offering a broader understanding of an organisation’s overall security posture. While pentesting focuses primarily on identifying exploitable vulnerabilities in a specific system or application through simulated attacks, a Security Review encompasses a thorough analysis of policies, configurations, architecture, and operational practices. It not only examines technical weaknesses but also considers human and procedural factors, ensuring that risks are identified and mitigated across the entire environment. By addressing both technical and strategic layers of security, a Security Review provides more meaningful insights and long-term resilience than the often narrow scope of pentesting alone.

Need expert help planning or interpreting your next pen test? Our security team specialises in tailored assessments that focus on real-world threats and business risk. Let’s talk.