Your business network changes more often than you may realise. New laptops are added, staff leave, software is updated, cloud tools are connected, suppliers are given access and remote working arrangements change. Each small change can introduce risk if it is not reviewed properly.
Network penetration testing helps you find weaknesses before attackers do. It is a controlled security test that looks at how someone could try to access your systems, move through your network or reach sensitive business data.
If your business has not reviewed its network security for some time, Network pen testing services can give you a clearer view of where you are exposed and what should be fixed first.
This matters because cyber attacks are still a serious issue for UK organisations. The UK Government’s Cyber Security Breaches Survey 2025/2026 found that 43% of UK businesses identified a cyber breach or attack in the previous 12 months, while phishing affected 38% of businesses.
What is network penetration testing?
Network penetration testing, often called network pen testing, is an authorised test of your network security. It uses controlled techniques to identify weaknesses in systems, devices, accounts, firewalls, remote access tools and internal network controls.
The National Cyber Security Centre describes penetration testing as a way of gaining assurance in the security of an IT system by attempting to breach some or all of that system’s security using similar tools and techniques to an adversary.
In plain English, a penetration test shows whether your defences could be bypassed and what an attacker might be able to reach if they found a way in.
1. You have not tested your network in the last 12 months
If your last network penetration test was more than a year ago, your business may already be overdue.
Cyber security is not static. A network that looked secure 12 months ago may now contain new vulnerabilities because of software updates, new devices, supplier access, firewall changes or staff turnover.
Annual testing is often a sensible starting point for many businesses. You may need more frequent testing if you handle sensitive data, operate in a regulated sector or rely heavily on online systems.
A yearly test helps you check whether old issues have been fixed, whether new risks have appeared and whether your controls still match the way your business works.
2. Your business has grown or changed quickly
Growth is positive, but it can create IT complexity.
If your business has added new staff, opened another office, changed suppliers, introduced new systems or moved more work into the cloud, your network risk may have changed too.
Common problems include:
Old accounts that remain active
Too many users with admin rights
New devices added without proper security checks
Remote access tools set up quickly and never reviewed
Cloud services connected without clear governance
These issues are easy to miss during busy periods. A network penetration test helps you check whether rapid growth has created hidden security gaps.
3. You rely on remote or hybrid working
Remote and hybrid working can make your business more flexible, but it also widens your attack surface.
Your staff may connect from home networks, shared workspaces, hotels or client sites. They may use laptops, mobile devices, VPNs, Microsoft 365, cloud applications and collaboration tools every day.
If remote access is not configured securely, attackers may have more opportunities to target your business. Weak passwords, exposed services, poor device management and inconsistent multi-factor authentication can all increase risk.
A penetration test can help identify whether your remote access setup is exposing your network unnecessarily.
4. You have had repeated phishing, malware or login alerts
One suspicious email does not always mean your network has been compromised. Repeated alerts, however, should not be ignored.
Phishing remains the most common type of cyber breach or attack affecting UK businesses, according to the Cyber Security Breaches Survey 2025/2026. If staff credentials are stolen, attackers may try to use them to access email, cloud systems, shared files or internal networks.
You should consider testing if you have seen:
Repeated suspicious login attempts
Malware warnings on user devices
Staff receiving targeted phishing emails
Unusual account activity
Unexpected password reset requests
Network penetration testing can help you understand what an attacker could do if an account or device was compromised.
5. You are preparing for cyber insurance, tenders or client checks
Many clients, insurers and larger supply chains now expect businesses to show that they take cyber security seriously.
You may be asked about vulnerability management, penetration testing, backups, access controls, incident response plans, multi-factor authentication and staff training.
If you cannot confidently answer those questions, it may be time for a proper network security review.
A penetration test can provide evidence that your business is checking its defences. More importantly, it helps you fix weaknesses before a client, insurer or attacker finds them.
6. You do not know who has access to what
Access control is one of the most common areas where businesses lose visibility.
Over time, users may collect permissions they no longer need. Former employees may not be fully removed from systems. External suppliers may retain access after a project ends. Admin accounts may be shared or used more widely than they should be.
This creates risk because attackers do not always need to break in through a complex technical route. Sometimes they only need to find one weak account.
A network penetration test can highlight whether poor access control could allow someone to move further through your network than they should.
7. You still use unsupported or ageing systems
Older systems can be difficult to secure. They may no longer receive updates, may not support modern security controls or may be connected to newer systems in risky ways.
This does not always mean you can replace everything immediately. Budgets, operations and specialist software may make that unrealistic.
However, you do need to understand the risk. A penetration test can help you see whether ageing systems are creating a serious weakness and what can be done to reduce exposure.
That might include network segmentation, stricter access controls, replacement planning, better monitoring or removing unnecessary internet exposure.
8. You have never tested internal network security
Many businesses focus on external security, such as firewalls and internet-facing systems. That is important, but internal network security matters too.
If an attacker gained access through a compromised laptop, stolen credentials or insecure remote access, what could they reach next?
Could they access shared files? Could they find admin credentials? Could they move from one system to another? Could they reach finance, HR or client data?
Internal testing helps answer these questions. It is especially useful for businesses that hold sensitive information or have grown without reviewing how systems are separated.
9. Your previous test findings were never fully fixed
A penetration testing report is only useful if action follows.
If your business had a test in the past but never completed the recommended fixes, you may still be exposed. Some issues may have become more serious over time, especially if the affected systems are still in use.
You should review previous findings and ask:
Were critical issues fixed?
Were medium-risk issues tracked?
Were old systems removed or protected?
Were changes retested?
Who owns the remaining actions?
If the answers are unclear, a fresh test can help reset priorities and give you a clearer action plan.
10. IT downtime would be expensive for your business
Network security is not only a technical issue. It is a business continuity issue.
If your systems were unavailable for a day, what would it cost? You might lose staff time, delay client work, miss sales, pay for emergency support or suffer reputational damage.
For example, if 15 employees lose 6 hours of work and the average employment cost is £30 per hour, the lost staff time alone is £2,700. That does not include lost revenue, recovery costs or client disruption.
Network penetration testing helps reduce the chance of preventable security incidents by identifying weaknesses before they cause damage.
What should happen after a network penetration test?
A good test should not leave you with a confusing technical report and no support.
You should receive clear findings, risk ratings, evidence and practical recommendations. The report should explain which issues need urgent action, which can be planned and which are lower priority.
After the test, your business should create a remediation plan. This may include patching systems, changing firewall rules, removing unused accounts, improving passwords, enforcing multi-factor authentication or replacing unsupported devices.
Retesting may also be useful, especially after critical fixes have been completed.
Speak to Northern Star about network penetration testing
If your business has grown, changed, delayed security reviews or relied on assumptions for too long, you may be overdue for network penetration testing.
Northern Star can help you assess your current position, plan a controlled test and turn the findings into practical improvements. You can get clear advice on network security, vulnerability management, Microsoft 365, cyber awareness, business continuity and wider IT strategy.
Contact Northern Star today to discuss network penetration testing and take the next step towards a more secure, resilient business.