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Network Penetration Testing

Network penetration testing London businesses can use to uncover hidden security weaknesses. A business network can appear reliable while still containing weaknesses that an attacker could exploit. Exposed services, outdated systems, poor segmentation, weak access controls and configuration errors may remain unnoticed during normal use.

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Automated security tools can identify known issues, but organisations may also need a controlled assessment of how those weaknesses could be combined or used in practice. Northern Star provides network penetration testing London businesses can use to understand where their IT environment may be exposed and what should be addressed first.

Our approach is informed by practical experience supporting business networks, cloud services, Microsoft 365 users, endpoint protection and day-to-day IT operations. This wider context matters because the seriousness of a finding depends on the system affected, its exposure, the data or access it provides and the effect a compromise could have on normal work.

Testing should not result in an unexplained list of technical terms.

Northern Star helps connect findings with business risk, giving technical teams and decision-makers clearer information for prioritising remediation.

The scope should be agreed before testing begins. Depending on the requirement, this may focus on internet-facing systems, an internal network, selected devices, remote access services or particular network segments. Critical systems, authorised test methods, operational constraints, named contacts and stop procedures should be documented so the work remains controlled.

Findings may relate to network configuration, exposed ports or services, unsupported software, authentication, permissions or paths that could enable unauthorised access. No test can prove that an environment is completely secure, but a well-scoped assessment can reveal weaknesses that deserve attention and provide an evidence-based starting point for improvement.

After testing, Northern Star can help explain the findings, distinguish urgent exposure from lower-priority issues and identify practical next steps. Actions may include patching, configuration changes, removing unnecessary services, strengthening authentication, reviewing access or planning broader security improvements.

Where a business requires regular discovery

Where a business requires regular discovery and follow-up rather than a point-in-time exercise, our vulnerability management services can support an ongoing process. Testing can also sit within Northern Star’s wider IT security services, helping organisations connect assessment, remediation, monitoring and incident readiness.

The aim is not to create fear or technical noise. It is to give your business a clearer view of risk and practical guidance that helps make its network harder to compromise.

Network penetration testing can be particularly valuable after infrastructure changes, when remote access has expanded, or when clients and insurers ask for stronger evidence of cyber security controls. It can also help an internal IT team challenge assumptions about segmentation, authentication and the exposure of critical services.

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Northern Star keeps the process proportionate to the agreed objective. A small business may need a focused review of internet-facing systems, while a larger organisation may require phased testing across several locations or network zones. By defining the question first, the assessment can concentrate on meaningful risk, minimise unnecessary activity and produce recommendations that the people responsible for remediation can realistically implement.

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Frequently asked questions

Network Penetration Testing

What is network penetration testing, and how is it different from vulnerability scanning?

The scope can include selected parts of an external or internal network, depending on what the business needs to understand. External testing may examine internet-facing services, remote access points, firewalls, gateways and public addresses that could be reached from outside the organisation. Internal testing may consider servers, workstations, network devices, segmentation, permissions and the access that a person or compromised device could obtain from within the environment.

Cloud-connected systems, branch offices, wireless networks or specific business-critical services may also be relevant, but they should not be assumed to be included automatically. Ownership and third-party hosting arrangements must be checked, because a business cannot authorise testing against systems it does not own or have permission to assess.

Before testing, Northern Star will need to understand the sites, address ranges, network design, important services and operational limitations involved. A smaller, clearly defined scope can be appropriate for a particular risk or recent change. A more complex organisation may need the work divided into phases so that testing remains controlled and findings can be linked to the correct system owners.

The first stage is scoping and authorisation. The organisation and tester agree which systems are included, which methods are permitted, when testing will occur and who should be contacted if an issue appears. Critical services, exclusions, maintenance windows, data-handling expectations and stop conditions should also be documented. This protects the business and gives the tester clear boundaries.

The technical work normally involves discovery, assessment and controlled validation of potential weaknesses. The precise activities depend on the agreed scope. Testing may identify exposed services, insecure configuration, outdated software, weak authentication, excessive permissions or network paths that could provide unintended access. Evidence is recorded so findings can be reviewed without repeating unnecessary actions against live systems.

The final stages are reporting and remediation planning. A useful report should explain the affected system, risk, evidence, potential impact and recommended action. Northern Star can help your technical team understand priorities and connect them with practical fixes. Where the results point to wider architectural or investment decisions, our IT consulting services can help turn findings into a structured improvement plan.

Testing is useful when the business needs assurance about network exposure or has made a significant change. Common triggers include opening an office, installing new infrastructure, introducing remote access, completing a migration, adding an internet-facing service, changing suppliers or connecting systems after a merger or acquisition. It may also be requested by a client, insurer, investor or governance process.

There is no single frequency suitable for every organisation. Risk, network complexity, sensitivity of data, rate of change, contractual requirements and previous findings all influence the schedule. Some businesses use an annual assessment as a baseline, with additional testing after material changes. Higher-risk or frequently changing environments may require a different approach.

Penetration testing should not replace regular patching, configuration review or vulnerability management between assessments. A test describes the environment within a defined scope and period; new vulnerabilities and changes can appear afterwards. Northern Star can help businesses combine point-in-time testing with ongoing security support, making it easier to track remediation and decide when another assessment is proportionate.

Testing may also be appropriate after previous findings have been remediated, particularly where management needs independent confirmation that the affected exposure has been sufficiently reduced.

Penetration testing should be carefully controlled, but no meaningful test of a live environment can be described as having absolutely no operational risk. That is why scoping is important. Northern Star should understand business-critical services, busy periods, fragile or legacy systems, third-party dependencies and any activities that need to be avoided. Testing windows and contacts can then be agreed around operational requirements.

Some checks may be low impact, while other validation could place additional load on a service or trigger security controls. Potentially disruptive techniques should not be used unless they are explicitly authorised and appropriate safeguards are in place. The rules of engagement can define stop conditions, escalation routes and what happens if the tester discovers an issue requiring immediate attention.

Businesses should make sure relevant backups, recovery processes and supplier contacts are current before testing critical systems. The objective is to gain useful security evidence without creating unnecessary disruption. Clear communication between Northern Star, internal IT teams and service owners helps the work remain coordinated and allows unexpected behaviour to be investigated quickly.

A useful report should serve both decision-makers and the people responsible for remediation. It may include an overview of the scope and approach, an executive explanation of the main risks and technical detail for each validated finding. Findings should identify the affected asset, evidence, severity, possible impact and a practical recommendation rather than relying on a generic score alone.

Context matters. A weakness on an isolated test system may not carry the same risk as the same issue on an internet-facing service containing sensitive information. Dependencies and possible attack paths can also change the priority. Northern Star can explain findings in plain English while retaining enough technical detail for internal teams or suppliers to act.

Afterwards, responsibilities and target dates should be agreed. Remediation may involve patches, configuration changes, access reviews, segmentation, authentication improvements or retirement of an unsupported system. Follow-up testing can confirm whether a specific issue has been addressed, although it does not guarantee that no other weakness exists. Northern Star’s wider support can help connect recommendations with day-to-day technical action.

No. A penetration test is an important assessment, but it is a point-in-time view of an agreed scope. It cannot examine every possible attack, predict future vulnerabilities or replace the controls and processes needed to manage security every day. Its value comes from revealing weaknesses, improving priorities and testing assumptions about the current environment.

Ongoing protection may include patching, secure configuration, identity and access management, endpoint security, email protection, backups, staff awareness and regular vulnerability review. Monitoring and response are also important because even well-protected organisations can experience suspicious activity. Northern Star’s managed SOC services can improve visibility and alert review, while MDR services can support detection and response across relevant systems.

The organisation also needs an incident plan. If testing or monitoring reveals possible compromise, Northern Star’s cyber incident response service can help assess the situation, contain risk and support recovery. Penetration testing works best as one part of this wider, layered security approach.

The cost depends on the size, complexity and type of environment being assessed. Important factors include the number of sites and addresses, whether the test is external, internal or both, the number of network segments, the technologies involved and any operational restrictions. Testing a small group of internet-facing services will usually require a different amount of work from assessing a multi-site network with legacy systems and several access levels.

Reporting, stakeholder meetings, remediation advice and follow-up testing can also affect the scope. A very low quotation may exclude the contextual review or practical guidance that makes findings useful, while a broad proposal may include systems that are not relevant to the immediate objective. Comparing providers therefore requires more than comparing day rates or a single total.

Northern Star will need sufficient information to define the authorised assets, intended outcome and expected deliverables before providing a suitable proposal. Clear scoping helps control cost and prevents misunderstandings about what has been tested. It also allows the work to focus on the areas that matter most to your business rather than applying an unnecessarily broad standard package.

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