Network Security Testing Guide: Essential Tools and Techniques

A classic pentest is a simulation of a cyber attack or an authorized hacking of a system, as well as a simulation of data leaks. Such network security tests aim to identify vulnerabilities and check the system's security. After testing, specialists record and analyze the system's weaknesses and select ways to eliminate them. A pentest differs from a vulnerability assessment—one is about a real hack or leak, and the second is about theoretical calculations and possible protection.  Calculations and possible protection. 

What is vulnerability? 

What is vulnerability?

A vulnerability is a weak point in a network security testing software, hardware, or security protocols. Various reasons can cause it:  

• programming errors;  
• incorrect system or equipment configuration;  
• outdated firmware;  
• design flaws;  
• human factor, and so on.  

Before a vulnerability is discovered, it only poses a potential threat. Malicious code is created to exploit a vulnerability. After this, an exploit is used to attack the vulnerable system. Attackers can exploit the vulnerability until the consequences become noticeable.   

Penetrating network security testing is carried out by penetration testers, who are cybersecurity specialists.

If the pentester is a full-time employee, he knows more about the system but cannot use this knowledge during testing to ensure objective results. A third-party specialist does not know all the system details but can find weaknesses that are not obvious to company employees. Therefore, for the purity of the experiment, third-party penetration testers are often involved.  

In short, while vulnerability assessment is theoretical, penetration testing is practical. A pentest involves penetration into the system and specific actions to identify weak spots. These network security tests can help you identify zero-day vulnerabilities, which are the most dangerous in IT. 

Who is a pentester, and what should he know?  

At the moment, the word hacker has a negative connotation. Therefore, the term pentester has become commonly used.  A pentester is an engineer/programmer who, on a contractual basis with the owner, searches for and exploits information system vulnerabilities to further improve the quality and security of the information system.  

For a pentester, it's not just about knowledge directly related to network security and testing information systems. It's about understanding the law, observing the environmental friendliness of your actions, and upholding the highest ethical standards. This includes knowing how to formalize your work and having the skill to prepare a comprehensive report on the work performed, a testament to your integrity and responsibility. 

Types of testers in network security testing 

Penetration testers can be external or internal. Let's figure out how they differ:

A comprehensive security system requires both specialists, so there is no problem choosing between these two areas. An internal expert understands the company's specifics, while an external expert can notice non-obvious problems that are not visible from the inside.

There is evidence that 98% of cyber-attacks are based on social engineering. Information security at the personnel level often depends on people's awareness of digital hygiene. Opening attachments from spam emails, clicking on dubious links, and storing your login and password on a piece of paper near your work computer are all weak points from a social engineering point of view.  

Application network security test identifies vulnerabilities in applications and associated systems:  

• web applications;  
• Web sites;  
• mobile applications;  
• Internet of Things applications;  
• cloud applications;  
• programming interfaces (API);  
• database;  
• components such as plugins, scriptlets, and applets are pieces of code that run on a page or application.  

Application testing often begins with checking against OWASP Top-10. This is a list of the most common and critical vulnerabilities in web applications from the international non-profit organization OWASP (Open Web Application Security Project).  

Common web application vulnerabilities include the possibility of malicious code injection, misconfigurations, and authentication failures. If penetration testers discover a vulnerability, they try to exploit it to gain unauthorized access to the application and its systems.  

There are several types of penetration testing: 

Physical network security penetration testing is performed to detect vulnerabilities and problems in physical infrastructure elements such as electronic locks, CCTV cameras, and sensors. Movies often show attackers creating a duplicate of someone's badge and using it to enter closed rooms, such as server rooms. Physical penetration testing just checks the feasibility of such an operation. 

Client-side penetration testing helps identify weaknesses or security flaws in employees' software. Vulnerable programs may include email clients, browsers, office applications, and graphic editors. This testing can identify attacks such as form hijacking, HTML injection, and malware infections.  

Wireless penetration testing is carried out to check the connections between all devices connected to the corporate Wi-Fi, including smartphones, laptops, tablets, and Internet of Things devices. Attacks by companies via Wi-Fi are quite common due to the many threats to wireless networks - from unauthorized access points to weak encryption algorithms. 

Main pentest methods 

Сonsider three main types of penetration testing: black box, white box, and gray box.

Black Box  

The specialist analyzes the company as if he were an attacker who wants to penetrate its systems via the Internet. He assessess weaknesses in infrastructure components that are connected to the Internet. For example, vulnerabilities in input forms on websites, servers, and office equipment connected to Wi-Fi. 

White Box  

The specialist receives information about the company not just as an employee but as an administrator with access to all systems. He examines how secure internal systems and databases are and whether it is easy to access sensitive information. This method helps to thoroughly check all internal resources and data protection from employees with different access levels.  

Gray Box 

The pentester knows how the company’s infrastructure is structured and plans attacks on resources or employees known to him. For example, he uses phishing emails, calls, or even personal communication. He scatters flash drives with malicious files in the office, gets a job as an intern, and gains physical access to the local network under the guise of a CCTV camera installer.

Penetration network security testing tools 

Pentest tools help solve specific problems or conduct a comprehensive pentest of a website or application. Let's look at the main ones: 

To conduct a pentest, it is not enough to simply launch the tool and then download the test report. In real life, automated network security penetration testing tools can fail, stop working, or simply not be suitable for a particular task. You can only rely on your qualifications. 

Blue, Red and Purple Teams 

Depending on the complexity of the testing being performed, several different teams may be involved:  

Integrating these teams into your testing process is crucial for comprehensive network security testing. 

What is included in penetration testing? 

Pentesting takes place in several stages. Let's look at them using the example of pentesting a web application: 

Collection of information 

This stage is similar to "spying" before an attack. The pentester searches for all available public information about the site, such as domain names, IP addresses, information about the site's structure, names of employees, and the technologies used in the web application.  

What tools will be useful:  

• WHOIS services - to obtain information about the domain owner.  
• Specialized search queries - to search for open information on websites and forums. 

Vulnerability Analysis 

At this stage, the penetration tester determines whether there are “holes” in the security of the application or network through which an attacker could try to penetrate. He scans the web application for vulnerabilities, сhecks open ports, analyzes server configurations, and examines the application code for weaknesses. 

What tools will be useful:  

• Nmap: for scanning open ports and identifying services.  
• Nessus or OpenVAS: to detect vulnerabilities in network devices.  
• Burp Suite or OWASP Zap: For web application security testing. 

Operation 

At this stage, the pentester checks how difficult it is to exploit the found vulnerabilities and penetrate the system, such as accessing a database.  

What tools will be useful:  

• Metasploit: to automate attacks and exploit known vulnerabilities.  
• SQLMap: for SQL injection testing.  
• Hydra: for authentication attacks. 

Maintaining access 

The longer hackers access systems and data, the more a vulnerability will cost a company. At this stage, the pentester estimates how long the system remains unaware of the breach. He installs tools that help maintain access to the system throughout testing. For example, Netcat or Meterpreter is used for remote access and installation of additional tools.

Cleaning up traces of presence 

Attackers may leave traces of a hack. For example, they may delete user data, subscribe, or log in from several devices. The more such traces left, the easier it is for a company to conduct an investigation after a hacker attack. Experienced hackers cover the tracks of their attacks, and penetration testers do the same after a penetration test.   

Data analysis 

The pentester analyzes the information he was able to obtain. Evaluates the potential damage from a successful attack. For example, how costly a customer data leak would be for the company. 

Documenting results 

The pentester creates a report that describes the identified vulnerabilities, gives recommendations for eliminating them, and provides an overall assessment of the web application's security. Here's what information it should contain so that the business understands how to proceed:  

• The structure and description of drawings, diagrams, and tables should be clear. The wording should be clear to the technical specialist and the marketing or HR staff.  
• A detailed description of the vulnerabilities: where they were found, their nature, and screenshots for clarity.  
• Description of the testing process, including methodologies and techniques (e.g., MITRE ATT&K framework). Pentests are carried out, among other things, to meet regulators' requirements, so in some cases, links to the FSTEC vulnerability databases are added.  
• Recommendations for eliminating vulnerabilities in the technology stack used by the customer.  
• Analytics. For example, the total number of vulnerabilities and the types that are most often encountered in the company, compared with previous pentests.  
• The consequences for the company if hackers take advantage of the vulnerability. For example, damage from a DDoS attack. In this case, attackers overload the server with requests until it crashes. 
• Example: Imagine a company's website, which includes a contact form for clients to reach a manager. Each form submission costs the company money. Under normal conditions, the site handles 50 submissions per minute. During a DDoS attack, submissions increase by 100 times to 5,000 per minute, mostly fake. If the attack lasts an hour, the company will lose a lot of money.  
• Summary of work with general recommendations and conclusion.  

These are the main criteria. 

Let's summarize and answer the most popular questions about how to test network security.