Internal Network Penetration Testing

Internal networks are an integral part of many businesses, the infrastructure typically consists of internal servers, hosts, and domains. Internal networks are an attractive target for cyber criminals as, if they can gain a foothold, successful compromise of an internally facing server could result in a companies entire network and data being compromised, it is therefore advised that companies make use on an internal network penetration test from a trusted penetration testing consultancy.

Making use of internal network penetration testing services will help ensure a company’s infrastructure is free from common security vulnerabilities, which, if exploited by cybercriminals, would negatively impact companies both from a financial and reputational perspective.

Network Penetration Testing

What is an internal network penetration test?

An internal network penetration test is a security assessment of an organisation’s perimeter systems, with the intention of highlighting vulnerabilities, resulting from outdated software or various misconfigurations.

To carry out the test, an expert penetration tester will simulate an attack on your organisation’s infrastructure, as if they were a hacker themselves with access to your internal network. 

There are three forms of methodologies that can be used in penetration testing; black box, grey box and white box. 

Black box testing is when the pen tester has no prior information about the organisation’s infrastructure or data, and starts from square one, as hackers do. 

Grey box testing (or, Gray box testing) is a penetration testing technique utilised to test a software product or application with partial knowledge of the internal structure of the application.

White box testing, on the other hand, is when the organisation provides information and data about the internal infrastructure, such as administrator level logins, so the pen tester has a full insight into the network and/or application. This is often the best approach for clients, as it will ensure the entire attack surface is covered.

Network penetration testing is often white or grey box, since the penetration tester will require access to an AD account. This type of pen test determines what’s at risk at this stage, and how might those assets be targeted. Having this priceless level of insight allows you to reinforce your cybersecurity before a real hacker potentially gains access to the internal network.

The Importance of Securing Internal Networks

While much attention is given to securing external networks from outside threats, internal network security often doesn’t receive the same level of focus. However, securing internal networks is equally, if not more, crucial. Here’s why.

1. Insider Threats

While external threats like hackers and cybercriminals are often highlighted in the media, insider threats are just as dangerous. These threats can come from disgruntled employees, contractors, or even someone who has mistakenly introduced malware into the system. By securing internal networks, organisations can mitigate the risks posed by insider threats.

2. Protection of Sensitive Data

Internal networks often house an organisation’s most sensitive data, including financial records, employee details, intellectual property, and customer information. If these networks are compromised, it can lead to significant financial and repetitional damage.

3. Maintaining Business Continuity

A breach in the internal network can disrupt business operations. For instance, ransomware can lock out essential data, making it inaccessible. By ensuring that the internal network is secure, businesses can ensure continuity and avoid potential downtimes that can result in financial losses.

4. Regulatory Compliance

Many industries are bound by regulations that mandate the protection of data. For instance, the healthcare industry must adhere to the Health Insurance Portability and Accountability Act (HIPAA), which requires the protection of patient data. A breach due to an insecure internal network can lead to heavy fines and legal consequences.

5. Avoiding the Domino Effect

If one system in an internal network is compromised, it can be used as a launchpad to attack other systems. This domino effect can lead to widespread damage. By securing each node and segment of the internal network, organizations can prevent a small breach from escalating into a major crisis.

6. Building Trust with Stakeholders

Customers, partners, and employees trust organisations to protect their data. A secure internal network is a testament to an organisation’s commitment to data protection. By prioritising internal network security, businesses can build and maintain trust with their stakeholders.

7. Adapting to the Evolving Threat Landscape

The world of cyber threats is constantly evolving. New vulnerabilities and attack vectors are discovered regularly. By focusing on internal network security, organisations can stay one step ahead of cybercriminals and adapt to the changing threat landscape.

What is the difference between internal penetration testing and a vulnerability scan?

An internal network pen test differs from a vulnerability scan as it offers the addition of manual testing to minimise false positives, as well as covering areas that scanners are unable to discover when enumerating a domain.

The Financial and Reputational Risks of Ignoring Internal Network Security

In today’s interconnected business landscape, the security of internal networks is paramount. While external threats often grab headlines, the dangers lurking within an organisation’s own digital walls can be just as perilous. Ignoring internal network security can lead to significant financial and reputational repercussions. Here’s an exploration of these risks.

1. Data Breaches

One of the most immediate financial risks of lax internal network security is the potential for data breaches. Such breaches can result in hefty fines, especially in the UK where regulations like the General Data Protection Regulation (GDPR) impose strict penalties on organisations that fail to protect personal data.

2. Loss of Intellectual Property

Internal networks often house an organisation’s most valuable assets, including trade secrets and intellectual property. A breach can lead to these assets being stolen, potentially giving competitors an unfair advantage and leading to financial losses.

3. Operational Disruptions

Cyberattacks, such as ransomware, can halt business operations. The downtime can result in lost revenue, and the cost of restoring systems can be substantial.

4. Loss of Customer Trust

Customers entrust organisations with their personal and financial data. A security lapse can erode this trust, leading to a loss of customers and revenue. The cost of acquiring new customers to replace those lost can be significant.

5. Reputational Damage

Beyond immediate financial losses, a security breach can tarnish an organisation’s reputation. Rebuilding a damaged reputation can take years and require considerable investment in public relations and marketing efforts.

6. Increased Insurance Premiums

Organisations that experience security breaches might face higher insurance premiums in the future. Insurers may view them as high-risk clients, leading to increased costs for cyber liability coverage.

7. Legal Repercussions

In addition to regulatory fines, organisations may face lawsuits from affected parties following a breach. The legal fees, coupled with potential settlements or damages, can be financially draining.

8. Loss of Competitive Advantage

A security breach can lead to a loss of competitive advantage, especially if proprietary data or strategies are exposed. Competitors might capitalise on this lapse, leading to reduced market share for the affected organisation.

How does internal penetration testing work?

The point of an internal penetration test is that it’s almost identical to an actual cyberattack. For this, the organisation will need to trust the professional pen tester entirely, and be prepared to let them ethically hack the system.

Here at Aardwolf Security, our team of penetration testing experts have established an effective 6-step system for performing an internal network penetration test.

    1. Reconnaissance

To get an idea of the client’s security level, a pen testing expert will first conduct an analysis, assessing the potential requirements, using Open Source Intelligence (OSINT).

    2. Scanning

Using automated scanners, the consultant will delve deeper into the infrastructure of the client’s servers scanning all 65535 ports, probing for services, their subsequent versions, and whether there are any associated misconfigurations. Further enumeration will be carried out against the domain, this will include the following assessments:

  • AD Enumeration
  • Kerberos Enumeration
  • Open SMB shares
  • Vulnerability/Exploit checks
  • MSSQL Enumeration 

    3. Manual assessment

This step is where most of the consultant’s time is utilised. Using a range of probing and verification techniques to delve deeper into the infrastructure, this process involves a range of specific manual penetration testing on the following areas: 

  • Authentication
  • Authorisation
  • Session management
  • Group policy configuration
  • Input validation and sanitisation
  • Server configuration
  • Encryption
  • Information leakage
  • Application workflow
  • Application logic


   4. Exploitation

Next, the vulnerabilities unveiled in the scanning and manual probing stages are raised to the client. Depending on the client’s business operations and the severity of the vulnerabilities, the client may give the consultant the go-ahead to subject certain issues to exploitation attempts.


    5. Reporting

After the exploitation attempts have been made, the pen testing consultant will produce a comprehensive report to highlight the impact likelihood of all system defects, and recommend solutions.


    6. Retesting

The sixth and final step of the process, offered exclusively at Aardwolf Security, is a free retesting service, once the client has actioned their software system solutions, to make sure that their infrastructure weaknesses have been resolved correctly and completely.

How long does it take to perform internal network penetration testing?

There are numerous factors that influence the scoping of a penetration test, such as:

  • The number of hosts and servers
  • Underlying infrastructure
  • Size and number of domains
  • Number of exposed services

Factors Influencing the Duration and Cost of an Internal Network Penetration Test

The duration and cost of these tests can vary significantly based on several factors. Here’s a closer look.

1. Scope of the Test

The broader the scope, the longer and more costly the test will be. If an organisation wishes to test only specific systems or applications, the duration and cost might be lower. Conversely, a comprehensive test of the entire network will require more time and resources.

2. Complexity of the Network

A complex network with multiple servers, applications, and devices will take longer to test than a simpler one. The presence of legacy systems, intricate configurations, or custom applications can also add to the complexity.

3. Depth of the Test

Penetration tests can range from basic vulnerability scans to deep, manual tests. The deeper the test, the more thorough the analysis, leading to a longer duration and higher cost.

4. Expertise of the Testing Team

A highly skilled team might command a higher fee but could potentially complete the test more efficiently. On the other hand, a less experienced team might charge less but take longer, potentially missing critical vulnerabilities.

5. Remediation and Retesting

If vulnerabilities are found and the organisation decides to fix them immediately, the testing team might need to conduct retests. This additional step can increase both the duration and cost.

6. Regulatory Requirements

Certain industries in the UK, such as finance or healthcare, might have specific regulatory standards for penetration testing. Meeting these standards can influence the depth, methodology, and consequently, the duration and cost of the test.

7. Use of Automated Tools vs Manual Testing

While automated tools can quickly scan and identify known vulnerabilities, manual testing is essential for uncovering more subtle, complex issues. A test that relies heavily on manual techniques might be more time-consuming but also more thorough.

8. Frequency of Testing

Some organisations opt for periodic tests, while others might choose continuous monitoring. Continuous testing can be more costly upfront but might lead to long-term savings by identifying and addressing vulnerabilities more promptly.

How much is an internal network penetration test?

An internal network pen test cost is calculated by the number of days a penetration tester will take to fulfil the agreed scope. The number of days can be determined by filling out our penetration testing scoping form or messaging us through our contact form to arrange a scoping call with one of our senior penetration testers.

Aardwolf Security utilise CREST accredited penetration testers for network penetration testing, with decades of experience performing web application security testing and website security testing. Get in touch today for a free quote.