TL;DR: Even mature IT environments often overlook key network pentest findings. From misconfigured firewalls to forgotten legacy systems, these blind spots can spell disaster for enterprise security. Addressing them can drastically reduce cyber risk.

10 Critical Network Pentest Findings IT Teams Overlook

By Richard Keenlyside, Global CIO & Transformation Expert

In the ever-evolving digital threat landscape, penetration testing is no longer a luxury — it’s a necessity. Despite its importance, I’ve seen too many IT departments across sectors—from manufacturing and retail to finance and utilities—ignore or downplay key pentest findings. These oversights often create unnecessary risk vectors that could have been proactively mitigated.

Here are 10 critical but often overlooked network pentest findings every IT leader and cybersecurity professional must address immediately.

1. Misconfigured Firewalls

Firewalls remain a foundational security control, but configuration drift and misaligned rule sets can expose internal assets. Common issues include overly permissive rules and forgotten "temporary" access exceptions.

Fix: Implement rule reviews quarterly. Use automation tools to validate configurations against policy.

2. Legacy Systems Still Alive and Kicking

It’s not uncommon to find forgotten systems still online—unsupported Windows servers, dusty Linux boxes in a corner rack, or even out-of-contract IoT devices quietly pinging the internet.

Fix: Introduce a full asset discovery audit and apply the principle of least privilege to all exposed endpoints.

3. SMTP & Email Gateway Weaknesses

Email is still the number one attack vector. Penetration testers often find weak email gateway configurations that allow spoofing, lack SPF/DKIM/DMARC enforcement, or expose internal mail servers.

Fix: Harden your email infrastructure and monitor mail logs for anomalies.

4. Unsecured Active Directory (AD) Structures

In my experience, AD often reveals excessive user privileges, lack of segmentation, and stale admin accounts. AD is a goldmine for lateral movement post-breach.

Fix: Conduct regular AD hygiene audits. Enable tiered admin roles and apply Just-In-Time (JIT) access.

5. Default or Weak Credentials

It’s 2025, yet default credentials like admin:admin still appear in scans. Weak password policies and shared logins offer attackers easy wins.

Fix: Enforce MFA, rotate passwords frequently, and eliminate default logins during initial deployment.

6. Patch Management Failures

Vulnerabilities in unpatched services—especially web servers and VPNs—remain among the top pentest findings. Patch latency opens up a clear window for exploitation.

Fix: Establish SLAs for patch deployment. Prioritise critical CVEs and automate patch validation where possible.

7. DNS and Network Segmentation Gaps

Flat networks and open DNS services often help attackers laterally explore environments once inside. This is frequently overlooked in test reports.

Fix: Design with microsegmentation in mind. Enforce DNS restrictions and monitor lateral traffic patterns.

8. Sensitive Data Exposure (Dev/Test Environments)

Development and testing environments often hold real data. These setups are rarely as secure as production and become prime targets.

Fix: Use anonymised data and enforce production-grade security policies in non-production systems.

9. Outdated Remote Access Protocols

Protocols like Telnet or SMBv1 still surface in pentests. These antiquated connections are often left enabled and unmonitored.

Fix: Disable legacy protocols and transition to modern encrypted alternatives like SSH, SFTP, and RDP with NLA.

10. Inadequate Logging and Monitoring

Perhaps the most underestimated risk: lack of proper logging. Without it, incidents go undetected for weeks or months. SOCs often lack visibility into low-level alerts.

Fix: Centralise log management, ensure time synchronisation, and deploy UEBA tools to spot anomalies.

Final Thoughts

As a CIO and board advisor across global enterprises, I’ve repeatedly seen how these pentest findings—when neglected—become entry points for costly breaches. Addressing these issues doesn’t require exotic tools or inflated budgets. What it takes is discipline, visibility, and leadership.

Every overlooked finding is a missed opportunity to prevent an incident. Regular penetration testing and proactive remediation must become standard operating procedures.

FAQs

Q: How often should a network pentest be conducted?

A: At least annually, but ideally quarterly for high-risk or regulated industries.

Q: Should cloud infrastructure be included in pentests?

A: Absolutely. Cloud misconfigurations are one of the leading causes of data breaches today.

Q: Can automated tools replace manual pentests?

A: No. Automation is essential, but manual testing uncovers business logic flaws and nuanced vulnerabilities that tools miss.

Closing Thoughts Don’t let familiar infrastructure lull you into a false sense of security. A pentest is not a one-time exercise—it's a window into how attackers see your organisation. Addressing overlooked findings today can prevent headlines tomorrow.

Richard Keenlyside is a Global CIO for the LoneStar Group and a previous IT Director for J Sainsbury’s PLC.