Network penetration testing has become more important than ever throughout the past year, but never more so than in 2021. An INTERPOL report shows alarming rate of cyberattacks during COVID-19 report in August showed a staggering increase in online crime rates. 

Cyber criminals have always targeted systems that may contain the most data possible for them to exploit, with the targets usually being businesses until now – as the report shows an increase in attacks on massive organizations and even critical government infrastructure. 

With more lockdowns set to be extended in different parts of the globe, a considerable amount of people will be online, which in turn means that more criminals are taking to the internet and finding innovative and creative new ways to exploit people browsing the web like you and me.

Now more than ever, businesses are going to need to invest in security, this guide will cover what network penetration testing is, the benefits and all of the other information needed to take action against cybercrime yourself if you feel up for the task!

What is Network Penetration Testing?

Network penetration testing in its simplest form is the testing of a businesses networking infrastructure and is often referred to as infrastructure penetration testing. This type of pen test can be performed one of two ways:

  • As an external network penetration test
  • As an internal network penetration test

These both have different purposes. For example, an internal network pen test is the test you would perform in order to gain a better understanding of what a cyber criminal could potentially do with just initial network access whereas an external network pen test was designed in order to test perimeter security controls and their overall effectiveness.

Most pen testers will perform both types of pen test on an organisation or business network, with internal testing mirroring any insider threat that could arise (such as an employee doing something malicious) and external mostly used for internet-facing assets (such as mail, web and FTP servers).

Should my business invest in penetration testing services?

One of the most frequent questions I’ve been asked: “do I even need to perform a pen test?” 


Followed by: “But, why?”

It’s simple. 

Performing one will open your eyes to a number of factors, some of which can have negative consequences on businesses life expectancy:

  • They assess and pinpoint weaknesses and vulnerabilities
  • Deeper assessments performed are able to spot potential major openings through minor gaps
  • Reporting tends to include specific advice, ranking vulnerabilities and just cleaner and easier to navigate

Businesses are frequently subjected to a plethora of threats with each of them having the potential to cause damage. Damaging attacks such as SQL injections or even accidentally leaving an error page visible can give an attacker the information required to perform that attack.

This is why deeper scans are required, to ensure attackers aren’t able to trigger a chain reaction of attacks through multiple smaller vulnerabilities. More often than not, companies overlook this fact and leave themselves open to an intruder creating intrusion sequences that pry open security gaps to reveal a much, much larger weakness.

How much does it cost for penetration testing services UK?

The price of penetration testing services in the UK (and around the world, for that matter) can vary depending on the scope of the project at hand. There are varying factors ch as complexity, Methodology, experience and others which affect the cost.

Realistically, if you’re offered a penetration test for less than £4,000 on a project with a massive complexity sounds too good to be true.

That’s because it is. 

Typically, for a small project the price is around £1,000-£3,000, a medium project around £3,000-£5,000 and a much larger project (£5,000-£25,000) however this is just an estimate and actual prices can and will vary.

Here to learn more about the typical processes of a pen tester and try learning for yourself? Just keep reading on for more information.

Example of a typical external network penetration testing process

Many people use different methods and tools for testing out the security of a network. Below is a shortened checklist of a process you can follow simply through the use of popular free tools:

  • Perform host discovery
  • Perform a port scan 
  • Perform OS fingerprinting
  • Scan for potential vulnerabilities

Performing host discovery during a pen test

At the very beginning stage of a pen test, the tester (or attacker) must gather as much intelligence as they can about a host server. 

More often than not, they do this through DNS footprinting in order to discover specific DNS information (A, MX, NS, SRV, PTR, SOA, CNAME). It’s possible to use network scanning tools such as Advanced IP scanner or NMAP to detect live hosts or any in the target network.

Here are some available tips and resources for host discovery, some of these require kali linux and access to the terminal:

  • Domain WHOIS: root@kali:~# whois
  • Traceroute: root@kali:~# traceroute

Performing a port scan

Once the host network has been discovered, it’s time to move on to performing a port scan. This process identifies open ports in the network, an open port can be the gateway that a potential hacker needs to access and deploy a malicious backdoor.

Some tips for port scanning:

  • Find all open ports on a network: root@kali:~# nmap –open   
  • To check a specific port: root@kali:~# nmap -p 80
  • To check for a range of ports: root@kali:~# nmap -p 80-200

Performing OS fingerprinting

OS fingerprinting is a fancy term given to identifying the version and operating system being used by the target system. Once this has been discovered, it’s time to move onto discovering the vulnerabilities and attempt to exploit it to gain total control of a system.

Some tips for OS fingerprinting: 

  • Identify: root@kali:~# nmap -A
  • IDServe is another great tool for users who prefer a GUI (graphical user interface)

Scanning for potential vulnerabilities

One of the most commonly used tools for scanning potential vulnerabilities within a system is Nessus. 

Nessus is a widely used vulnerability scanning tool which searches deep within software for bugs and tries to identify a specific way to violate the security of the software in question. 

BONUS: Some useful network penetration testing resources for 2021

  • Popular frameworks: KaliLinux, Backtrack5
  • Recon tools: MxToolbox, nslookup, dig, netcraft, smartwhois, dnsstuff
  • Discovery: NMAP, Maltego, OpManager, LANsurveyor
  • Port Scanning: NMAP, Zenmap, Megapin, Netscan tools pro
  • Enumeration: Superscan, Netbios Enumerator, Jxplorer
  • Vulnerability Scanning: Nessus, Nexpose, SAINT
  • Packet Sniffing: Wireshark
  • Password Cracking: Rainbow crack, Ncrack, Cain & Abel
  • Exploitation: Metasploit

It’s going to be a crazy year, with COVID still running rampant and cyber crime rising. It’s hard to tell exactly who or what is going to be affected. 

For the businesses who can afford a penetration testing service I would personally recommend it, however for those who cannot and are too small to afford the higher rates, I wouldn’t really worry about the threat of cyber criminals. 

Hopefully, this article has still given all readers whether you’re a small business owner, large business owner, or future pen tester more of an insight into network penetration testing.

Connie Cole
Connie Cole

Connie has been working within the cyber security industry for almost 10 years now, specialising in penetration testing or more specifically web application pen testing. She believes that everyone online should have access to this information and strives to provide people with the knowledge they need to begin within the industry and for others to stay safe online.

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