Penetration testing

Penetration testing steps: How-to guide on pentesting

Stephan Miller
May 30, 2024 by
Stephan Miller

Penetration testing, often called pentesting, is a critical part of modern cybersecurity defense strategies. In our digital world, where cyber threats are constantly growing and evolving, organizations must proactively identify and address vulnerabilities in their systems and networks. Penetration testing simulates real-world attacks, allowing security professionals to uncover weaknesses before malicious actors exploit them. 

Follow this step-by-step guide on how to do penetration testing, covering each of the penetration testing phases and highlighting its growing significance in 2024 and beyond. 

Understanding penetration testing 

Penetration testing is the art of simulating a cyberattack on your systems with your permission. The goal is to uncover weaknesses so they can be mitigated before cybercriminals exploit them. Pentesting can be classified into three main types: 

  • Black box testing: Here, the tester acts completely blind, just like a real attacker with no prior knowledge. They rely on publicly available information and standard hacking techniques to probe your defenses. 
  • White box testing: This pentester has all the inside information, like system blueprints and configurations. This method is ideal for in-depth testing of specific systems or applications, leveraging the tester's knowledge to pinpoint vulnerabilities with greater precision. 
  • Gray box testing: This approach to penetration testing blends elements of both black and white box testing. 

Penetration testing is like a stress test for your system's security. By simulating real-world attacks, pentesting helps you: 

  • Patch security holes once vulnerabilities are identified 
  • Strengthen defenses, allowing you to implement stronger controls and detection mechanisms 
  • Boost confidence by knowing your defenses have been thoroughly tested 

Pre-penetration testing steps 

Before the penetration process begins, certain preparatory pentest steps are crucial to ensure the test is effective and legal. These steps lay the groundwork for a successful test. 

Planning and scope 

The first step is defining the scope and objectives of the pentest. It involves outlining the "rules of engagement," including: 

  • Targets: What systems and applications will be tested? Are there any off-limits areas? 
  • Objectives: What are you hoping to achieve? Is it identifying critical vulnerabilities, testing specific security controls or assessing overall security posture? 
  • Legal considerations: Ensure you get proper authorization and comply with relevant data privacy regulations. 
  • Engagement rules: What techniques are allowed during the pentest? Are there limitations on the level of disruption permissible? 


After the scope of the pentest is known, the tester gathers information about the target environment, including its network topology, applications, operating systems, user accounts and other important details. This step is often called Open Source Intelligence (OSINT) because most of the information collected is gathered from publicly available sources. 

Here are some common reconnaissance techniques: 

  • Using search engines to find public information about the target organization's website, employees, technologies and publications (annual reports, press releases). 
  • Exploring social media platforms like LinkedIn to gather information about the business's employees and departments and potentially discover useful data that employees may have inadvertently leaked. 
  • Leveraging DNS lookup tools to find publicly registered domain names associated with the organization. 
  • Using data archive websites, government records and subscription sites like Hoover's or LexisNexis to gather data that may be harder to find in strictly public sources. 

Pentesters will often use OSINT Framework and other OSINT tools to automate and structure the reconnaissance step. 

Core penetration testing steps 

The reconnaissance stage should give the penetration tester enough information to begin actively scanning the target environment, identify vulnerabilities and attempt to exploit them to understand their possible impact. 

Scanning and enumeration 

This step creates a detailed map of the target, revealing potential entry points for further exploration. It is also where the tester touches the target systems. 

Scanning in this step includes using techniques like ping sweeps and port scans and the list of active targets gathered in the reconnaissance phase to find open ports and possibly the services available on the system. Tools like Nmap and Zenmap will help to automate this process. 

The next step, enumeration, lists and identifies the services and resources available on these ports. For example, TCP 25 might be open, which usually indicates an SMTP server, but the system administrator may obfuscate services and run another service on that port. Enumeration tools, like Nmap's scripting engine or Nessus, use techniques like banner grabbing and service fingerprinting to identify the actual services behind the open ports. 

Vulnerability analysis 

Once the tester has discovered the services running on the target system, it's time to find weaknesses. Vulnerability analysis involves examining the discovered systems and services for known security flaws. These flaws could be software bugs, misconfigurations or weak security settings. 

To get a complete picture, the pentester will use: 

  • Automated vulnerability scanning: Specialized tools, like Nessus or OpenVAS, can scan systems and compare them against databases of known vulnerabilities. 
  • Manual vulnerability assessment: Experienced testers can dig deeper, manually analyzing the systems and services for vulnerabilities that automated tools might miss. 


Once vulnerabilities have been discovered, the tester attempts to leverage them to gain unauthorized access or escalate privileges within the system. There are many types of exploitation techniques, and the specific approach depends on the vulnerability. Some common techniques include: 

  • SQL injection: Exploiting flaws in how applications interact with databases 
  • Cross-site scripting (XSS): Injecting malicious scripts into websites to steal data or hijack user sessions 
  • Buffer overflows: Taking advantage of programming errors to inject malicious code 


Here, the penetration tester maintains access to the compromised system, explores its internal workings and identifies additional targets within the allowed scope. This helps assess the potential damage a real attacker could cause. 

The actions taken during this stage will depend on the initial foothold gained, but common activities include: 

  • Moving laterally within the network to gain access to other systems 
  • Stealing sensitive data 
  • Interrupting critical operations 


The final stage involves documenting the entire process. This report will outline the vulnerabilities discovered, the exploitation techniques employed and the potential impact of each vulnerability. It should also include clear recommendations to fix the vulnerabilities and strengthen the organization's security posture. 

Post-penetration: remediation and follow-up: 

The ethical hacker's report becomes a valuable blueprint for action. They will work closely with the organization to prioritize and address the identified vulnerabilities. This may involve patching software, reconfiguring systems or implementing additional security controls. 

Once remediation efforts are complete, it's wise to conduct follow-up penetration testing. This will help ensure the vulnerabilities have been addressed effectively and no new ones have emerged because of the remediation process. It's the final security checkup to ensure a healthy digital environment. 

Penetration testing tools and resources 

Many open-source and commercially licensed tools can make the penetration tester's job much simpler. Here is just a sample: 

  • Scanners: Nmap, Nessus and OpenVAS map target networks, identify open ports and discover running services. 
  • Vulnerability assessment tools: Nexpose and Qualsys can automate vulnerability scanning, comparing systems against vast databases of known weaknesses. 
  • Exploitation frameworks: Metasploit, a widely used open-source framework, provides a library of exploits that can test the severity of vulnerabilities. 
  • Password cracking tools: John the Ripper and Hashcat can be used to test password strength. 
  • Packet analyzers: Tools like Wireshark capture and analyze network traffic. 

While all these tools can be extremely useful, it is important to keep them up to date and test new tools as they become available. New vulnerabilities are discovered all the time, and attackers develop new techniques. Staying up to date with the latest tools helps ensure your pen tests can identify constantly evolving vulnerabilities. 

Penetration testing and cybersecurity careers 

With cyber threats constantly on the rise, the demand for skilled penetration testers is growing, and pentesting skills can be valuable across a wide range of cybersecurity positions, including: 

  • Penetration tester: These are the foundational skills you'll need in the role of a full-time penetration tester. 
  • Security analyst: Professionals can leverage pentesting skills to analyze security posture, identify risks and Implement security controls. 
  • Security engineer: Penetration testing expertise empowers professionals to design and implement security solutions that can withstand attacks. 
  • Security architect: In this role, pentesting knowledge is crucial to help design and oversee the organization's overall security architecture. 

While formal education is a plus, penetration testing skills are highly sought after, and penetration testing certifications can significantly enhance your resume and your career as a penetration tester. Here are a few popular options to consider: 

  • Certified Ethical Hacker (CEH): This vendor-neutral certification provides a broad foundation in penetration testing methodologies and tools. 
  • PenTest+: Offered by CompTIA, this certification focuses on the practical application of penetration testing skills. 
  • OSCP (Offensive Security Certified Professional): This performance-based certification emphasizes hands-on experience through a rigorous practical exam. 

Infosec's penetration testing certification boot camp will prepare you to pass both the CEH and PenTest+ exams with five days of immersive training using real-world scenarios. 

The future of penetration testing 

The penetration testing field is constantly changing to keep pace with cyber threats. Here are some emerging trends that are reshaping the field: 

  • Automation and AI: Repetitive tasks can be automated, freeing testers to test for advanced threats and social engineering. AI can analyze data to identify vulnerabilities and adapt testing strategies. 
  • Cloud focus: As cloud adoption grows, so will the need for cloud security expertise in penetration testing. 
  • DevSecOps integration: Security testing can be blended with the development process for proactive defense. 

The future of cybersecurity belongs to those who adapt. For aspiring and current professionals, developing penetration testing skills is a future-proof investment and certifications along with continuous learning will make you a valuable asset. 

Pentesting FAQ 

What are the prerequisites for becoming a penetration tester? 

A strong foundation in networking, operating systems and security principles is essential. Experience with scripting languages like Python and familiarity with popular penetration testing tools are also good skills to possess. Certifications can validate your skills, and hands-on experience is key. 

How do penetration testing certifications impact salary and job prospects in cybersecurity? 

Certifications like CEH, PenTest+ or OSCP demonstrate your commitment to the field and prove you have the skills. They can enhance your resume and make you a more attractive candidate, leading to higher earning potential. 

Can penetration testing be automated, and what are the limitations? 

Repetitive tasks like vulnerability scanning can be automated, allowing testers to focus on more strategic activities. However, automation has limitations. Human expertise is still important for tests requiring creative problem-solving, social engineering assessments and the exploitation of complex vulnerabilities. The ideal scenario combines automation with human ingenuity.

Stephan Miller
Stephan Miller

Stephan Miller is a senior software engineer. He currently works as a full-stack web and mobile developer for Shamrock Trading Corporation. Stephan has worked as a developer for over 20 years and as a freelance writer for over a decade. In his spare time, he spends time with his family and reads and attempts to write science fiction.