Five Common Mistakes Firms Make After a Pen Test

1. Treating the Report as a Tick-Box Deliverable

Too often, firms view the final report as an end rather than a starting point.
Once the document is filed for audit purposes, little action follows.

This undermines the intent of testing, which is to drive continuous improvement and validate the effectiveness of existing controls.

To avoid this, firms should:

• Assign ownership for each finding to a responsible individual
• Log findings in a risk register or GRC platform
• Link remediation to risk appetite and operational resilience metrics

This ensures that test outcomes are embedded into governance rather than compliance paperwork.

Learn more about our Penetration Testing Services for U.K. Financial Firms and how structured remediation support improves value delivery.

2. Delaying Remediation Activities

Time to remediate is one of the most critical indicators regulators watch. The longer vulnerabilities remain open, the higher the exposure to exploitation. In practice, delays often occur because remediation tasks are not prioritised against business impact.

A high-severity vulnerability in a low-risk system can consume attention while critical issues elsewhere remain unresolved.

To prevent this, firms should adopt a risk-based prioritisation model and define clear timelines, for example:

• High severity: remediation within 15 working days
• Medium severity: within 30 days
• Low severity: within 60 days

External references such as the NCSC vulnerability management guidance provide practical benchmarks for setting appropriate targets.

3. Failing to Conduct a Re-Test

A common oversight is assuming that fixes have worked without verification.
Regulators increasingly expect firms to demonstrate closure validation rather than rely on internal confirmation.

A structured re-test confirms that vulnerabilities have been remediated effectively and that no new issues were introduced.
It also provides objective evidence for internal audit, regulators and investors.

Best practice is to conduct a re-test within 30 days of initial remediation completion.
This transforms penetration testing from a one-off assessment into a closed-loop assurance cycle.

Discover how our Cyber GRC Services integrate re-testing and assurance reporting into broader compliance frameworks.

4. Failing to Conduct a Re-Test

Penetration test results are often written in technical language that fails to translate easily for Boards or non-technical leaders.

Without business context, even severe vulnerabilities may not receive the attention they deserve.

Each finding should therefore be mapped to:

• Impacted business service or process
• Associated financial, regulatory or reputational risk
• Recovery time objective (RTO) or tolerance breach potential

This approach aligns with FCA Operational Resilience Policy Statement PS21/3, which expects firms to demonstrate that technology risks are managed in line with business continuity objectives.

Providing this context ensures test results contribute to meaningful risk discussions at executive level.

5. Not Learning from Pen Testing Mistakes Over Time

Many firms treat each penetration test as an isolated event. Without historical analysis, recurring weaknesses and systemic control gaps remain invisible.

Trend analysis reveals whether vulnerability counts are reducing, recurring, or shifting between domains such as cloud, applications or networks. This enables CISOs and COOs to track cyber maturity and demonstrate progress to the Board and regulators.

A simple dashboard combining data from previous tests can transform the reporting conversation from “what went wrong” to “how far we have improved.”

For guidance on building these metrics, see the Bank of England’s CBEST framework, which outlines how threat-led testing feeds into capability measurement.

Bringing It All Together

Turning penetration testing into measurable business value requires:

1. Timely remediation with accountability and validation
2. Integration of findings into governance and risk processes
3. Business context that aligns with operational resilience goals
4. Continuous trend analysis to inform investment priorities

When managed in this way, penetration testing becomes a strategic indicator of resilience rather than a compliance exercise.

For further perspective, read How Often Should Financial Firms Conduct Penetration Tests to align frequency and follow-up actions.

In Summary

The value of penetration testing lies not in the discovery of vulnerabilities but in how effectively those insights are acted upon.

Avoiding these five common pen testing mistakes enables financial firms to demonstrate not only technical improvement but also leadership in cyber governance and resilience.

In a regulatory environment that increasingly values outcomes over processes, this distinction matters.