Secure pentests: what matters and what can go wrong

A penetration test (pentest) is a powerful tool for improving IT security – but without the right preparation, it can also pose risks. Companies therefore often ask themselves: What do I have to pay attention to during a pen test and can something break? In this article we look at the success factors for a secure pentest and highlight what dangers exist and how they can be prevented. From detailed planning and communication to choosing the right service provider to the learning process from each test run, we show how pentests can be carried out in such a way that they bring maximum benefit without harming companies.

Table of contents

This post is part of a multi-part blog series. The following articles have already appeared:

Planning, scoping and communication of a penetration test

A successful pentest begins with thorough preparation long before the actual test. Precise planning, clearly defined scoping and transparent communication with the customer are the focus. It should be clearly defined in advance in scoping which systems and areas will be tested and what the exact goal of the pen test is. This shared understanding ensures that no misunderstandings arise later and that everyone involved pulls together.

Ongoing communication during the test is equally crucial. Everyone involved – from management to IT administration – must know what is happening at all times. This is the only way to avoid important services from being accidentally impaired or even crashed. Particularly in hybrid environments (i.e. when classic on-premises systems are linked to cloud services), an impairment could otherwise have serious consequences. For this reason belong regular status updates, exchange during critical activities, and a detailed final report with presentation on the best practices of each pentest project. Such measures ensure that the customer is always informed and that no unwanted surprises occur.

Possible risks and what can go wrong

Despite the best planning, it is important to be aware of the potential risks. A penetration test actively intervenes in the network environment and systems – what is the worst that can happen? Some examples from practice:

• Exposure of sensitive data: During a penetration test, pentesters can gain access to personal, business-critical information or data from third parties.
• Unexpected interactions: IT environments are complex ecosystems and sometimes react unpredictably to testing. Services or entire systems can fail due to an attack or just a network scan or exhibit temporary abnormal behavior, disrupting legitimate operations and affecting employees in their work.
• Data loss or corruption: Unintentional write access by exploiting vulnerabilities can damage or delete data, resulting in data loss. Pentesters are careful to avoid this, but residual risk can never be completely ruled out.

It is important to be aware of these risks and minimize them as much as possible. Be it through careful approach, the provision of isolated test environments, or through safeguards such as backups before the start of the test. Damage can usually be prevented through constant consultation and coordination with customer contacts. Should something unforeseen happen, clear and precise communication helps: everyone involved can react immediately and initiate countermeasures to quickly restore normal operations.

Choosing the right pentest provider

Another key factor for a successful and secure penetration test is choosing the right service provider. Not every pentest provider works with the same professionalism and care. So how do you recognize a reputable provider? Important criteria include:

• Experience and expertise: The provider should already have extensive experience in various areas of IT security and ideally in the company's industry.
• Clear methodology: A pentest has a proven, structured process. Ideally, it uses recognized frameworks (e.g. OWASP Continuous Penetration Testing Framework, PTES, PTF, OSSTMM, CSF, MSF). This guarantees a certain completeness and comparability of the results.
• Comprehensive documentation: Transparency is important. Reputable providers document exactly which tools and techniques they use and which systems have been tested. This means the customer knows afterwards what exactly was done.
• Specific recommendations for action: A good pentest report is not limited to listing vulnerabilities found. It prioritizes them and also provides clear recommendations on how to close these vulnerabilities and how the overall security architecture can be improved.
• Flexibility and adaptability: Since IT landscapes are constantly evolving, the pentest partner must be able to react flexibly to changes. Be it a short-term change in scope or the emergence of new technologies – a good service provider adapts its methodology to the situation.
• Protection: Before the test begins, the “Rules of Engagement” (ROE) should be established with the explicit consent (permission to attack) to carry out the penetration test and signed by all parties involved. In addition, the provider must have professional liability insurance with sufficient coverage to cover possible claims for damages from third parties.
• Communication: Regular status updates during the test and clear contact persons help to keep interruptions during the test to a minimum and to escalate sensitive issues in a timely manner.

Anyone who takes these criteria into account when choosing a provider lays the foundation for the penetration test to be carried out carefully and responsibly. It's worth checking references and having the provider's approach explained in detail in a preliminary discussion.

New perspectives through changing testers

Interestingly, it can also be helpful to do it regularly change the pentest provider or at least the internal team. What initially sounds counterintuitive has a simple reason: every security expert brings his or her own background and perspective. A team that has tested a company multiple times knows the environment very well, but over time could become operationally blind to certain vulnerabilities. A fresh view from outside A new pentest team, on the other hand, can bring previously overlooked problems to light.

By changing perspectives – a “second opinion” approach to IT security – organizations continually gain fresh insights into their security architecture. This contributes significantly to continuous improvement. Of course, a change should not take place in the middle of an ongoing project, but rather at regular intervals (e.g. annually or biennially) It may make sense to hire a new service provider. It is important that the documentation of previous tests is complete and handed over to the new partner so that no knowledge is lost.

Conclusion

A pen test can provide enormously valuable insights – provided it is planned and carried out with due care. Careful preparation, clear communication and the selection of a competent partner are the cornerstones for a smooth process. In this way, the risks associated with such an intrusive test can be reduced to a minimum. And if something does go wrong, a good provider with transparent communication and quick reactions will ensure that there is no major damage. Ultimately, a pen test should uncover vulnerabilities, not create new problems – with the right measures in advance and the correct implementation, this is exactly what can be achieved. In this way, the pen test becomes a real benefit for security – and not a new source of danger.

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Sebastian Kokott is a senior consultant at CONET. As an IT security expert, he understands the importance of a robust security concept to protect company data and systems from threats.