Network Penetration Testing: All You Need to Know

According to the report by Cybersecurity Ventures, there was a significant increase in global cybercrime costs, projected to reach $9.5 trillion in 2024. Ransomware attacks impacted 66% of organizations and cost businesses around $20 billion in 2023. And IBM states that it takes security teams around 277 days to identify and contain a data breach.

Some would say these numbers are not demonstrative enough since the data from large corporations distort the statistics. Yet, the fact that cyber security remains one of the core risks for any company using technology (which is literally any company these days) is undeniable. Data breaches are one of numerous problems.

This was the bad news. The good news is that there are many ways to prevent a vast array of security threats. Network penetration testing is one of the security services that lets you ensure it. For those looking for the answers we’ll explain everything below.

What is Network Penetration Testing?

So, what is penetration testing in network security? Network penetration testing, or simply pen testing, is a simulated attack on a computer network or system. 

Its purpose is to identify technical and business logic vulnerabilities within the network. It’s a controlled stress test for a network designed to uncover potential weaknesses before real hackers can exploit them. Such vulnerabilities can include misconfigurations, software bugs, weak spots in security controls, low security awareness within the team, and more. 

Pen testers act like attackers. They mimic a cybercriminal’s actions, using a mix of automated tools and manual penetration testing techniques to discover entry points and potential weak areas. 

Types of Network Penetration Testing

Network penetration testing simulates cyberattacks to identify and address security vulnerabilities. Various types focus on specific threat scenarios or network components. Combining multiple methods helps uncover a wide range of vulnerabilities. Below are the primary types, with emphasis on external and internal testing:

External Penetration Testing

External testing simulates attacks originating from outside the organization’s network perimeter. It aims to identify vulnerabilities that external attackers could exploit in publicly accessible assets:

• Web Servers and Applications: Checking for issues like SQL injection and cross-site scripting.
• Firewalls and Routers: Evaluating configurations to block unauthorized access effectively.
• Email Servers: Assessing susceptibility to phishing and spam attacks.
• Public IP Addresses and Domains: Scanning for open ports and services that could serve as entry points.

Understanding external weaknesses allows organizations to strengthen their defenses against outside threats.

Internal Penetration Testing

Internal testing assumes an attacker has breached external defenses or is an insider with legitimate access. It focuses on vulnerabilities within the internal network:

• User Access Controls: Ensuring appropriate permissions and preventing privilege escalation.
• Network Segmentation: Verifying proper segmentation to contain breaches.
• Sensitive Data Protection: Identifying unsecured data accessible to unauthorized users.
• System Configuration and Patch Management: Checking that systems are up-to-date to mitigate known vulnerabilities.
• Insider Threat Assessment: Evaluating risks from employees or contractors who might misuse access.

Internal testing helps protect against threats originating from within the organization.

Other Types of Penetration Testing

• Wireless Penetration Testing: Evaluates the security of wireless networks to prevent unauthorized access.
• VPN Penetration Testing: Assesses the security of Virtual Private Networks used for remote access.
• Cloud Penetration Testing: Examines cloud infrastructures for misconfigurations and vulnerabilities.
• Remote Access Penetration Testing: Tests the security of remote access solutions like RDP and SSH.
• Network Device Penetration Testing: Targets routers, switches, and other hardware for vulnerabilities.
• VoIP Penetration Testing: Inspects Voice over IP systems for potential exploits.
• Segmentation Penetration Testing: Verifies the effectiveness of network segmentation controls.
• Firewall Penetration Testing: Evaluates firewall configurations to ensure proper enforcement of security policies.
• Virtualization Penetration Testing: Examines virtual environments and hypervisors for weaknesses.
• IPv6 Penetration Testing: Explores vulnerabilities specific to IPv6 implementations.
• SCADA/ICS Penetration Testing: Targets industrial control systems to protect critical infrastructure.
• Network Application Penetration Testing: Examines applications for insecure protocols or data leakage.
• Denial-of-Service (DoS) Penetration Testing: Simulates DoS attacks to test network resilience.

Importance of Network Pen Testing

Let’s move to the practical value of a network pen test. Like any security check, it helps you identify weaknesses before they cause problems. To be more specific, a network penetration test ensures:

• Proactive security. You get to detect vulnerabilities before malicious actors can exploit them.
• Compliance. Many industries have strict security regulations requiring regular pen testing.
• Risk management. You can manage risks and protect your assets better if you understand your network’s weaknesses.
• Business continuity. A strong security posture prevents disruptions cyberattacks can potentially cause.
• Increased loyalty. Partners and customers expect businesses to have robust security measures in place. 

Network pen testing is all about proactivity and preventing negative and dangerous scenarios. It’s easier for businesses that run pen tests to stay ahead of the competition.

What Threats Network Pen Test Helps to Prevent

Network penetration testing is crucial for identifying and mitigating vulnerabilities within an organization’s network infrastructure. By simulating real-world attack scenarios, it helps prevent a variety of network-specific threats that could compromise the confidentiality, integrity, and availability of data and services. Below are some of the key threats that network penetration testing helps to prevent: 

Unauthorized Network Access

Network penetration testing uncovers weaknesses that could allow attackers to gain unauthorized access to network resources. This includes identifying:

• Weak Authentication Protocols: Such as outdated or improperly configured protocols like PAP instead of more secure options like CHAP or MS-CHAPv2.
• Default Credentials and Weak Passwords: Devices and services left with default login credentials or using easily guessable passwords.
• Unsecured Remote Access Services: Open SSH, Telnet, or RDP ports without proper security controls.

Network Misconfigurations

Network pentesting identifies misconfigurations that could be exploited:

• Firewall Misconfigurations: Incorrectly configured rules that allow unwanted inbound or outbound traffic.
• Router and Switch Misconfigurations: Improper settings that could enable routing loops or allow unauthorized access.
• Improper Access Control Lists (ACLs): Inadequate ACLs that fail to restrict traffic appropriately.

Insecure Network Services and Open Ports

Network penetration testing detects unnecessary or insecure services running on the network:

• Unnecessary Open Ports: Services that are not required but are running and accessible, increasing the attack surface.
• Legacy Protocols: Use of outdated protocols like FTP, Telnet, or HTTP instead of secure alternatives like SFTP, SSH, or HTTPS.
• Vulnerable Services: Identifying services with known vulnerabilities that require patching or decommissioning.

Weaknesses in Network Authentication Protocols

Network pentesting exposes vulnerabilities in authentication mechanisms:

• LAN Manager (LM) and NTLMv1: Use of outdated Windows authentication protocols susceptible to cracking.
• Insecure LDAP Implementations: Unencrypted LDAP traffic that can be intercepted and manipulated.
• Weak EAP Methods in Wireless Networks: Such as EAP-MD5, which are vulnerable to certain types of attacks.

Man-in-the-Middle (MitM) Attacks

Network pen tests help prevent MitM attacks by identifying:

• ARP Spoofing Vulnerabilities: Weaknesses that allow attackers to intercept traffic by spoofing ARP messages.
• DNS Poisoning: Misconfigurations that enable attackers to redirect traffic to malicious sites.
• SSL Stripping: Opportunities for attackers to downgrade secure HTTPS connections to HTTP.

Denial-of-Service (DoS) Attacks

Testing assesses the network’s resilience against DoS attacks:

• Resource Exhaustion: Identifying services that can be overwhelmed by traffic floods.
• Protocol Exploits: Vulnerabilities in protocols (e.g., TCP SYN flood) that can be exploited to disrupt services.
• Application-Level DoS: Attacks targeting specific applications with malformed requests.

VLAN Hopping and Network Segmentation Bypasses

Penetration testing verifies the effectiveness of network segmentation:

• VLAN Hopping Attacks: Identifying configurations that allow attackers to access VLANs they shouldn’t.
• Inter-VLAN Routing Issues: Misconfigurations that permit unauthorized traffic between VLANs.
• Weak Segmentation Controls: Opportunities to bypass network segmentation through dual-homed devices or misconfigured gateways.

Exploitation of Network Device Vulnerabilities

Network pentesting targets routers, switches, firewalls, and other network hardware:

• Firmware Vulnerabilities: Outdated firmware susceptible to known exploits.
• Backdoors and Default Accounts: Hidden accounts or backdoors left by manufacturers or previous administrators.
• SNMP Exploits: Insecure SNMP configurations using default community strings like “public” or “private”.

Wireless Network Attacks

Network penetration testing of wireless networks helps prevent:

• Unauthorized Access: Identifying open or weakly secured Wi-Fi networks.
• Encryption Weaknesses: Use of deprecated encryption standards like WEP or weak WPA/WPA2 configurations.
• Rogue Access Points: Detecting unauthorized devices mimicking legitimate network resources.

DNS and DHCP Attacks

Testing uncovers vulnerabilities in critical network services:

• DNS Cache Poisoning: Exploiting weaknesses that allow manipulation of DNS records.
• DHCP Starvation and Spoofing: Attacks that can lead to denial of service or man-in-the-middle scenarios.

ARP Spoofing and Poisoning

Network pentesting identifies susceptibility to ARP-based attacks:

• Traffic Interception: Ability of attackers to redirect traffic through their own devices.
• Session Hijacking: Exploiting ARP vulnerabilities to hijack user sessions.

Eavesdropping and Traffic Analysis

Network pen tests reveal unencrypted communications that could be intercepted:

• Plaintext Protocols: Use of protocols like HTTP, Telnet, or FTP without encryption.
• Weak Encryption Algorithms: Employing outdated algorithms like DES or RC4.

Insecure Network Protocols

Network penetration testing identifies the use of insecure protocols:

• Deprecated Protocols: Identifying and recommending the discontinuation of protocols like SMBv1.
• Unencrypted Email Transmission: SMTP configurations not using TLS.

SNMP Attacks

Testing exposes weaknesses in Simple Network Management Protocol configurations:

• Default Community Strings: Using “public” or “private” as community strings.
• SNMP Version 1 and 2c: Versions that lack encryption and are vulnerable to interception.

Rogue Devices on the Network

Penetration testing detects unauthorized devices:

• Unauthorized Wireless Devices: Identifying and locating rogue access points.
• Physical Device Access: Discovering unauthorized devices connected to network ports.

Main Methods of Network Pentesting

The most commonly used methods of network security penetration testing are black box, grey box, and white box testing. 

Black Box

The method is helpful for simulating real-world attacks from unknown sources. In this case, a tester has no prior knowledge of the network. They approach the test like an outsider would. In other words, they use all available tools and techniques to map the network, identify vulnerabilities, and attempt to exploit them. 

White Box

It is ideal for evaluating how well your network security withstands an in-depth examination. A tester has full access to information about the network. It can include architecture diagrams, source code, system configurations, and more. They can thoroughly analyze the network in detail and pinpoint specific vulnerabilities black box testing might overlook. 

Gray Box

This method helps identify insider threats and vulnerabilities one can exploit with some degree of knowledge. A pen testing specialist receives partial information about the network. It can be login credentials, basic system information, or something similar. Gray box testing balances the advantages of the previous two methods.

Network Penetration Testing Process

How to pentest a network? The process usually involves four key stages. However, it may vary depending on your system’s particularities and business objectives. 

Step 1: Gathering Information

The initial stage of network penetration testing is known as reconnaissance. Testers aim to collect as much information about the target network as possible. This may involve:

• Gathering publicly available information from websites, social media, and other sources.
• Obtaining information from internal sources, getting familiar with network diagrams, system inventories, and security policies.
• Interviewing key personnel to gain insights into infrastructure and operations.

The more detailed the information, the more precise the test can be. 

Step 2: Discovery

Next, testers scan the network for vulnerabilities. During the discovery phase, they can use manual techniques or automated tools, such as vulnerability scanners. Common discovery techniques include:

• Port scanning to identify weaknesses in network ports prone to attacks. 
• Vulnerability assessment with automated tools to detect known vulnerabilities.
• Banner grabbing to extract information from network services to identify the software and versions in use.
• Enumeration to gather information about users, groups, and resources.

The security team looks for misconfigurations, missing patches, unprotected access points, and other issues. This data provides a comprehensive view of the network’s weak spots.

Step 3: Exploitation Process

The next step of network penetration process is exploiting the identified vulnerabilities. Testers attempt to gain unauthorized access to systems, intercept data, initiate privilege escalation, and more. The aim is to see how easy it is to break through the network’s defenses. This may involve:

• Using known security vulnerabilities to compromise systems.
• Developing custom tools or scripts to exploit newly discovered vulnerabilities.
• Tricking users into revealing sensitive information or performing actions to compromise the network.

Exploitation is critical in determining the actual risks. Having a list of flaws isn’t enough. Your team must understand how far an attacker could go.

Step 4: Reporting and Recommendations

All findings are compiled into a detailed network pen test report that lists and explains all discovered vulnerabilities. It should include:

• Vulnerability details – description of each identified vulnerability with its severity and potential impact noted.
• Exploitation methods – explanation of how vulnerabilities were or could be exploited.
• Recommendations – steps to address the described vulnerabilities and improve the network’s security.

The recommendations entail clear steps for fixing the issues. These suggestions could range from applying patches to strengthening access controls and better team education. 

Step 5: Retesting (Optional)

Sometimes, organizations choose to perform a retest after fixing the problems. This step confirms that the fixes work as intended and no new issues appeared during implementation. Retesting is also helpful if you have specific success metrics set.

Network Penetration Testing Best Practices

Network security testing is only effective with the right strategy. Much depends on your network’s specifics, and industry-specific aspects and challenges can impact it, too. Still, some rules and practices will be helpful for all teams. 

• Define clear goals and scope. Be specific about what you want to achieve. Based on this, you’ll understand what parts of the network to test.
• Run internal and external testing. Assess risks from both outside and inside the network. It will help you stay protected from attacks by hackers and someone with access to your network.
• Test regularly. New network devices, users, and configurations alter the security state. Periodic testing ensures that new vulnerabilities haven’t appeared.
• Simulate real-world attacks. Use the same tactics, techniques, and procedures that an average hacker would. Only in this case can you set up realistic defenses. 
• Use a risk-based approach. Prioritize fixes based on the potential impact of each weakness. Address high-priority vulnerabilities first.
• Maintain your security policies. Use the results of pen tests to improve access controls, patch management, and other defensive measures.
• Work with experienced testers. Find skilled penetration testing experts familiar with your industry and specific challenges.
• Consider third-party testing. Cooperating with an independent cyber security company will ensure objectivity and help avoid conflicts of interest.

Using penetration testing best practices above will help you get accurate results and address vulnerabilities effectively. 

Conclusion

Simulating real-world attacks helps organizations stay protected. By learning their weaknesses, they can protect their networks and businesses against cyber threats. A network penetration test is one effective method for this. 

Perhaps one of the most important outcomes of network penetration tests is the ability to prioritize your security efforts to stay prepared but distribute your resources efficiently.

Remember that testing is never a one-time event. But by investing in regular checks, you keep your business safe, responsible, and more attractive to customers, partners, and key stakeholders.

If you don’t know where to start with network pen testing, Iterasec will gladly assist. We’ve got a team of 20+ cybersecurity specialists and experience working with a vast range of clients – from startups to Fortune 500 companies. With the holistic approach our penetration testing services offer, you’ll get a custom and effective strategy to keep your network and assets secure. Get in touch to learn more about how it works.