Top 5 Mistakes Pentesters Make and How to Avoid Them

Top 5 Mistakes Pentesters Make and How to Avoid Them

Penetration testing (or pentesting) is a critical component of a company’s cybersecurity strategy, helping organizations identify vulnerabilities before malicious actors can exploit them. However, even experienced penetration testers can make mistakes that compromise the effectiveness of a test. These errors can lead to missed vulnerabilities, wasted resources, or even unintended damage to the systems being tested.

In this blog post, we’ll explore the top 5 common mistakes made by pentesters and offer tips on how to avoid them to ensure more successful and accurate tests.

1. Not Scoping the Test Properly

One of the most critical mistakes pentesters can make is not properly scoping the penetration test. A poorly defined scope can result in unnecessary tests that waste time and resources, or worse, leave critical vulnerabilities undetected.

Why it matters: Without a clear scope, pentesters may miss testing key systems or areas, leaving vulnerabilities exposed. Additionally, overextending the scope could lead to testing systems that are out of the project's boundaries, which could result in accidental disruptions to critical operations.

How to avoid it: Always work closely with the client or internal stakeholders to define a comprehensive scope. This should include:

• The systems, networks, or applications to be tested.

• Specific concerns or risks the organization is facing.

• The testing methodology and tools to be used.

• Timeframe and rules of engagement (what’s allowed and what’s off-limits).

Clear communication and agreements upfront can prevent misunderstandings and ensure the test is focused and effective.

2. Failing to Simulate Real-World Attack Scenarios

Penetration testers sometimes focus too much on running automated tools and miss out on simulating real-world attack scenarios. While tools can identify obvious vulnerabilities, human attackers often use creative, multi-step attack chains to breach a system. Over-reliance on automated scanning tools can lead to shallow testing, missing critical flaws that would be exploited in a more sophisticated attack.

Why it matters: An attack scenario in the real world is rarely a simple vulnerability on a single system; it involves lateral movement, privilege escalation, and social engineering, among other tactics. Automated tools are important, but they should complement, not replace, manual testing and thinking like an attacker.

How to avoid it: Pentesters should aim to replicate real-world attack scenarios as much as possible. This involves:

• Thinking creatively about potential attack vectors.

• Using a combination of automated tools and manual techniques.

• Testing beyond the obvious vulnerabilities, including attack paths like phishing, social engineering, or insider threats.

• Attempting to bypass detection and defenses to replicate sophisticated adversaries.

3. Neglecting Post-Exploitation Activities

Once a pentester gains access to a system, the job is far from over. Post-exploitation refers to the steps taken after initial access has been gained—such as pivoting to other systems, escalating privileges, exfiltrating data, or maintaining persistence. Some pentesters overlook these activities, focusing only on finding and exploiting vulnerabilities.

Why it matters: A successful pentest isn’t just about finding vulnerabilities; it’s about showing how attackers could leverage those vulnerabilities to cause damage. Without post-exploitation, the pentester misses the full picture of what an attacker could accomplish once inside the network.

How to avoid it: Pentesters should conduct post-exploitation activities to:

• Gain deeper access into the network.

• Identify sensitive data or systems that could be targeted.

• Demonstrate how attackers could maintain access or escalate privileges.

• Provide a full picture of the attack chain, from initial access to exfiltration or destruction.

4. Ignoring the Importance of Communication

Effective communication is key to a successful pentest, yet many pentesters neglect to clearly communicate their findings with clients or stakeholders. It’s one thing to find a vulnerability; it’s another to explain its potential impact and how to mitigate it.

Why it matters: A vulnerability report that lacks context can leave stakeholders uncertain about its severity or how to act. Clear communication ensures that the findings are understood and that action can be taken quickly to address the issues.

How to avoid it: Pentesters should focus on:

• Writing clear, concise reports that explain the vulnerabilities in layman's terms for non-technical stakeholders.

• Providing actionable recommendations, including prioritizing vulnerabilities based on risk.

• Being available to discuss findings in person or through follow-up meetings to clarify any questions.

Good communication helps ensure that the value of the pentest is fully realized and leads to meaningful improvements in security.

5. Overlooking Security Controls and Defenses

Penetration testers sometimes focus too much on identifying weaknesses in a system and fail to assess the strength of existing security controls. Firewalls, intrusion detection/prevention systems (IDS/IPS), security information and event management (SIEM) systems, and endpoint detection and response (EDR) tools are just a few of the security defenses that need to be evaluated during a penetration test.

Why it matters: If pentesters don’t evaluate how well security controls are functioning, they may miss opportunities to exploit misconfigurations or weaknesses in the defenses that could be easily bypassed by attackers. Additionally, overlooking these systems gives a false sense of security, as a real attacker would likely try to bypass defenses before targeting the vulnerable systems directly.

How to avoid it: Pentesters should assess:

• The configuration and effectiveness of security controls (e.g., firewalls, IDS/IPS).

• The detection capabilities of SIEM systems and how well they flag suspicious activities.

• Whether multi-factor authentication (MFA) is being used effectively.

• How easily an attacker can bypass defenses, such as bypassing anti-virus software or EDR systems.

Conclusion

Penetration testing is an essential part of any organization's cybersecurity strategy, but even experienced pentesters can make mistakes that compromise the effectiveness of their assessments. By avoiding the top 5 mistakes outlined in this post—poor scoping, lack of real-world attack simulations, neglecting post-exploitation, poor communication, and overlooking security controls—pentesters can conduct more thorough and impactful tests that better protect their clients and identify critical vulnerabilities before they are exploited.

By continuously refining processes, improving communication, and adopting a more holistic testing approach, pentesters can better mimic the methods of real-world attackers and help organizations strengthen their cybersecurity defenses.

To learn more about our services and how we can help protect your systems, visit https://www.vaptern.com/services or contact us directly.