Penetration Testing - When to Test, What You Might Find and What to do Next - Cyber and Fraud Centre

Penetration testing plays a critical role in understanding how vulnerable your systems really are. But many organisations still ask the same questions:

When should we do one?

How often is enough?

What happens after we get the report?

This blog breaks down when penetration testing makes sense, the issues that most commonly show up, and how to turn results into meaningful security improvements, rather than having a forgotten document left on a desk.

When should you run a penetration test?

A penetration test is most useful when it reflects your current risk profile, not just a date on the calendar. Common triggers could include:

Major Infrastructure or System Changes

Any significant change can introduce new weaknesses, including:

Cloud migrations or new hosting environments.
New applications, portals, or integrations.
Changes to network architecture or identity management.

Testing after major changes can help confirm controls are working as expected.

Compliance or Audit Requirements

Many frameworks and regulations either explicitly require penetration testing or strongly expect it, including:

ISO 27001
Cyber Essentials Plus
Data protection and sector-specific data

In these cases, pen testing supports audit evident and governance rather than acting as a tick-box exercise.

Periods of Growth or Increased Exposure

Rapid growth, entering new markets, or potentially onboarding large clients often increase your attack surface. Pen testing during growth phases helps ensure security keeps pace with the organisation.

Suspicion of Weaknesses or Incidents

If you’ve experienced unusual behaviour, a near miss, or a confirmed incident, a penetration test can help establish how an attacker might gain access and what else could be exploited by criminals.

How Often Should Penetration Testing Be Done?

There’s no single correct frequency, but common approaches include:

Annually – often driven by audit or policy requirements.
Post-change – after major infrastructure or application updates.
More frequently for higher-risk systems – such as internet-facing services or systems handling sensitive data.

The right frequency depends on your risk appetite, complexity of systems and exposure. Not just best-practice guidance.

Risks of Poorly Planned Penetration Testing

Not all pen tests provide the same value. Common pitfalls experienced by organisations could include:

Unclear scope, leading to gaps or irrelevant findings.
Over-reliance on automated tools, with little manual input.
Reports full of technical detail without any prioritisation.
No retesting, meaning fixes are assumed rather than verified.

A poorly executed test can create a false sense of security, or could overwhelm teams with redundant findings.

The Most Common Vulnerabilities Found in Pen Tests

Across all sectors and organisations, we have found a number of common areas that should be focused on:

Misconfigurations

Incorrect cloud, firewall, or application settings remain the most frequent causes of exposure. These often arise from default configurations or rushed deployments.

Missing or Delayed Patching

Known vulnerabilities (CVEs) persist because updates are postponed, dependencies are overlooked, or asset inventories are incomplete.

Weak Authentication and Access Controls

This includes:

Weak or reused passwords.
Excessive user permissions.
Lack of multi-factor authentication or password management protocols.

These issues may enable cyber attackers to move further through your systems once initial access is gained.

Legacy Systems and Forgotten Services

Older systems, test environments, or unused services are frequently exposed simply because no one realises they are still live, in use and under no particular person’s control.

Why These Issues Remain So Common

For many organisations, security isn’t failing because of lack of intent. It’s usually due to:

Limited time and resource.
Competing operational priorities.
Security responsibilities spread across multiple roles.
Lack of visibility over the whole system environment.

How To Reduce Risk Before A Pen Test

While penetration testing is not a replacement for good security hygiene, organisations could catch many issues early by:

Maintaining an up-to-date asset list.
Applying regular patching and updates.
Reviewing user access and permissions.
Running vulnerability scans between tests.
Using configuration baselines for cloud and infrastructure.

These steps help ensure a pen test focuses on meaningful weaknesses, rather than avoidable basics.

After The Test: Managing Prioritisation

One of the biggest challenges comes after a pen test report is delivered. Areas to think about are:

Triage based on risk, not volume

Not every finding needs immediate action. Prioritisation should consider:

Likelihood of exploitation.
Potential business impact.
Exposure of the affected system.

This helps the team focus on what genuinely matters first.

Turn findings into tracked actions

Pen test results should feed into:

Risk registers.
Security improvement plans.
Ownership and timelines for remediation.

Without this, issues may stall once audit pressure passes.

Retesting and Continuous Checking

Fixes should be validated. Periodic retesting or continuous vulnerability scanning helps confirm that:

Changes worked as intended.
New weaknesses haven’t been introduced.
Security posture improves over time.

How Compliance and Regulation Shape Penetration Testing

For many organisations, pen testing is driven by governance rather than incidents.

When pen testing is a regulatory expectation

Depending on sector and framework, testing may be required to:

Protect personal or sensitive data.
Support audit readiness.
Demonstrate ongoing risk management.

Documenting results properly

Good documentation matters. This includes:

Test scope and methodology.
Clear remediation evidence.
Retest results where applicable.

This makes audits smoother and avoids repeated testing for the same issues.

Integrating testing into wider governance

Pen testing works best when it supports:

Security policies.
Risk management processes.
Board-level oversight.

Rather than being a standalone activity, it becomes part of how the organisation manages its overall cyber risks.

Making Penetration Testing Work for You

Pen testing is most effective when it’s planned, contextual and acted upon. Done well, it helps organisations understand real-world risks, strengthen defences, and make informed decisions – not to just meet compliance requirements.

The Cyber and Fraud Centre – Scotland team delivers CREST-certified penetration testing that mirrors real-world threats, ensuring your business stays ahead of cyber criminals.

Find out more here or book a free 15-minute consultation to see how a penetration test can support the growth of your organisation.

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