What is Penetration Testing? A 2025 Guide to Ethical Hacking Your Systems

• Penetration testing pen testing is a simulated cyberattack against your own systems by ethical hackers to uncover security weaknesses before real attackers do.
• It involves mimicking real world hacker techniques with permission to find vulnerabilities in applications, networks, and people, then reporting those issues so they can be fixed.
• Why it matters: Pen testing helps organizations stay ahead of evolving threats by identifying and fixing gaps proactively, and it’s often required or recommended for security compliance e.g. PCI DSS.

Penetration testing is essentially asking, How would a hacker break into my system? and then letting a trusted expert find out. In the first 2-3 sentences Penetration testing is a cybersecurity practice where ethical hackers simulate real attacks on your systems to find and fix vulnerabilities.

It’s like hiring someone to try to break into your bank’s vault if they succeed, you learn exactly where the weak spots are and can strengthen them. This proactive test helps stop cyberattacks before they start by uncovering issues you didn’t know about, so you can patch them in advance.

Cyberattacks are only getting more sophisticated and frequent every year. Organizations can’t afford to wait for a breach to find out their security flaws. Penetration testing in 2025 is a must have for a robust security strategy, it provides an attacker’s perspective on your defenses, which is crucial for staying ahead of modern threats.

It’s also a key requirement in many compliance frameworks for example, PCI DSS 4.0 explicitly requires regular pen tests. In short, pen testing helps ensure that your locks are secure, your walls are fortified, and your team is prepared for whatever cyber threats come next.

What is Penetration Testing?

Penetration testing (pen-testing) is a controlled, ethical hacking exercise conducted to evaluate the security of a computer system, network, or application.

In a pen test, skilled security professionals often called ethical hackers or penetration testers attempt to identify and exploit vulnerabilities using the same tools and techniques as malicious attackers but with permission and clear rules of engagement.

The goal isn’t to cause harm, but to reveal how an adversary could break in so that those weaknesses can be fixed before a real attack occurs.

Think of it this way, if you want to test the strength of a fortress, you might invite an expert to try to attack it. Pen testers do exactly that for your digital fortress.

They might try to crack weak passwords, slip malicious inputs into web forms, trick your employees with phishing emails, or even physically see if they can walk into your server room.

Throughout the test, they carefully document any vulnerabilities found such as an unpatched software bug, a misconfigured firewall, or a lax security policy along with how they exploited it and what data they could access.

Crucially, penetration tests are authorized and planned in advance. The testers operate under a contract or agreement that outlines the scope which systems can be tested, the methods allowed, and any limitations. They also have a duty to avoid unnecessary disruption.

The testing is non destructive, meaning the aim is to prove a weakness exists for example, by retrieving a sample of sensitive data without causing damage or significant downtime. After the test, they restore the system to its original state and share detailed results.

In essence, a penetration test is a legal, safe simulation of a cyberattack that produces invaluable insights about your security.

Who Performs Pen Tests?

Penetration tests are typically performed by experienced security professionals who specialize in offensive security. Often, organizations hire external consultants or firms. These ethical hackers come in with fresh eyes and no prior knowledge of the target, which helps them spot blind spots that insiders might miss.

This is sometimes called a black box test when the tester knows nothing about the system in advance, akin to a real outside attacker. Many pen testers hold advanced certifications OSCP, CISSP, CREST, etc. and have a background in areas like network engineering or software development, which they leverage to think like attackers.

Some companies build in-house red teams for continuous testing, but even then, bringing in outside experts periodically is common to ensure an unbiased assessment.

It’s worth noting that some of the best penetration testers have unconventional backgrounds, for example, former black hat hackers turned good, or self taught tinkerers with a knack for finding bugs.

What matters is the mindset and skillset a good pen tester is creative, curious, and methodical. They follow ethical guidelines and legal requirements strictly obtaining written authorization before testing and handling any sensitive data with confidentiality.

In short, pen testing is performed by trusted pros who know how to break things the right way for the right reasons.

Why Penetration Testing Matters in 2025

Cybersecurity isn’t static as defenses improve, attackers adapt, and new vulnerabilities emerge constantly. Penetration testing matters in 2025 more than ever because it’s one of the most effective ways to stay ahead of these evolving threats. Here’s why a solid pen testing program is so important in today’s landscape:

Find Unknown Vulnerabilities:

• Pen tests can uncover security flaws that automated tools or routine audits miss. Real attackers are crafty, chaining together minor issues into major exploits.
• A skilled pen tester can simulate these complex attack chains to reveal hidden weaknesses.
• This might be something like a subtle logic flaw in an application, a misconfigured cloud storage bucket, or a backdoor that was accidentally left in code.
• By discovering these issues through testing, you get the chance to fix them before a malicious actor finds them.

Prevent Costly Breaches:

• The average cost of a data breach keeps rising, with financial and reputational damage that can be devastating not to mention potential ransomware payouts or regulatory fines.
• Penetration testing is a proactive strike it helps you plug leaks in your ship before you hit stormy weather.
• For example, if a pen test shows that an outdated VPN server could let intruders into your network, you can address it now rather than learn the hard way from an incident.
• This proactive approach can save huge costs by avoiding incidents or minimizing their impact.

Compliance and Customer Trust:

• Many industry regulations and standards require regular penetration testing or security assessments. If your business handles credit cards, health records, or personal data, chances are you have compliance obligations.
• For instance, PCI DSS 4.0 for payment card data mandates penetration testing of networks and applications. ISO/IEC 27001 information security management and SOC 2 service organization controls strongly recommend pen testing as well.
• By conducting pen tests, you’re not only ticking the compliance box you’re demonstrating to customers and partners that you take security seriously.
• It builds trust when you can say, We regularly test our defenses and fix what we find.

Attacker’s Perspective & Continuous Improvement:

• Perhaps the biggest benefit is gaining insight into how an attacker views your organization. Pen testers think outside the box and often emulate the latest tactics that criminals are using.
• Their report might show, for example, how a low privilege account with a weak password could be leveraged to pivot through your internal network and ultimately steal sensitive data. That outside in perspective is invaluable.
• It often leads to improvements not just in technical controls like patching a server but also in processes and training like refining incident response plans or giving staff better security awareness training.
• Many organizations use pen testing results as a roadmap for security enhancements over the coming year.

Keeping Up with Sophisticated Threats:

• In 2025, threats like supply chain attacks, zero day exploits, and AI driven phishing campaigns are on the rise. Penetration testing helps validate new defenses against modern threats.
• For example, if you’ve invested in an endpoint detection and response EDR system, a pen test can evaluate whether that EDR actually catches a simulated attack. It’s a way to verify that your fancy security tools are configured right and doing their job.
• Essentially, pen testing is a reality check, an ongoing training exercise for your security posture that keeps you sharp and ready.

After the infamous WannaCry ransomware attack in 2017 crippled many organizations like Britain’s NHS health system, those organizations massively increased their security testing.

The UK’s National Health Service now commits to at least annual penetration tests across its networks following national NCSC standards to ensure such vulnerabilities are caught early.

Since implementing regular pen testing and other measures post WannaCry, the NHS has not suffered another major incident on that scale.

The lesson? Pen testing can turn a wake up call into an action plan that prevents history from repeating itself.

How Penetration Testing Works Key Phases

Penetration testing is not a one time hack and done activity it’s an organized process with several key phases.

Different methodologies label the steps slightly differently NIST, for example, outlines four main stages, planning, discovery, attack, reporting, some others expand to seven phases, but they all cover similar ground.

Here’s a breakdown of how a typical pen test engagement unfolds:

Planning & Reconnaissance:

• This is the preparation phase. The scope and goals of the test are defined, rules of engagement are agreed upon, and all legal permissions are sorted out, you always get written consent before testing.
• For example, the organization might specify that the tester can target the corporate web app and employee network, but must not disrupt the production database.
• Once scope is set, the tester gathers initial intelligence on the target often called reconnaissance or OSINT open source intelligence.
• They might look at public information company websites, domain records, leaked credentials, or even an office’s physical layout from Google Maps. The idea is to identify potential entry points and high value targets.
• This recon can reveal useful nuggets, say, an old subdomain running an outdated application, or an employee’s LinkedIn profile listing a specific technology the company uses hinting at possible vulnerabilities.

Scanning & Discovery:

• In this phase, the tester actively probes the target systems to discover vulnerabilities. They’ll typically use network scanning tools like Nmap to map out the target environment.
• For instance, Nmap might reveal that a server has ports 80 and 443 open, likely a web server, and perhaps port 22 SSH open information that helps the tester plan next steps.
• The tester may also run vulnerability scanners such as Nessus, OpenVAS, or Qualys to quickly identify known issues like missing patches or common misconfigurations.
• The scanning phase is about enumeration: finding out what systems and services are running, and what potential weaknesses exist.
• This could uncover things like an FTP server with anonymous access, or a web application using an old version of WordPress with known exploits.
• It’s a bit like rattling all the doorknobs and windows on a house to see which ones are open or weakly locked.

Exploitation Gaining Access:

• Now comes the exciting part, the simulated attack. In the exploitation phase, the pen tester uses the information gathered to attempt to breach the system.
• This could involve a variety of techniques depending on what was found.
• For a web app, the tester might try SQL injection or cross site scripting attacks to pull data or bypass logins.
• For a network, they might exploit an unpatched service or use stolen credentials to get into a machine.
• Tools like the Metasploit Framework are often used here, as they provide a collection of ready made exploits and payloads to launch at target systems.
• If a vulnerability is confirmed, the tester will try to establish access for example, opening a remote shell on a server or entering a restricted area of an application.
• They will then attempt to escalate privileges turn that foothold into deeper access.
• This could mean obtaining admin rights on a compromised system or pivoting to another system on the network.
• Throughout exploitation, the tester is careful to remain stealthy where possible to test detection controls and avoid causing any unintended damage.
• The goal is to demonstrate the impact of each vulnerability e.g., through this hole.
• I was able to retrieve 10 customer records or I gained domain admin access which would allow complete control of the network without actually harming the systems or data.

Post Exploitation & Analysis:

• After attempting and hopefully achieving some level of access, the tester explores how far they could go.
• Post exploitation activities might include maintaining access e.g. installing a temporary backdoor or creating a test user account to simulate advanced threats, or pivoting to other network segments to find additional vulnerabilities.
• However, since this is a friendly test, these actions are tightly controlled. At this stage, the tester is also thinking about clean up and evidence.
• They’ll remove any backdoors or accounts they created, and ensure they haven’t inadvertently left the client’s system in a vulnerable state.
• All the information gathered, the vulnerabilities, the data compromised, the time spent undetected is analyzed to paint the full picture of the security posture.
• The element of stealth is important: part of the analysis may note whether the organization’s security team detected the testing activity. If not, that might indicate monitoring gaps.

Reporting & Remediation:

• Finally, the pen tester compiles a detailed report of their findings. This report is arguably the most important deliverable of the whole process.
• It typically includes an executive summary, non technical overview for management, a list of discovered vulnerabilities with severity ratings, proof of concept details on how each was exploited, and recommendations for fixing each issue.
• For example, if SQL injection was found in a web form, the report will explain how it was exploited and advise parameterized queries or input sanitization as a fix.
• A good report doesn’t just dump raw findings, it prioritizes them critical, high, medium, low risk so the organization knows what to tackle first.
• After the report is delivered, the organization’s security/IT team swings into remediation patching software, updating configurations, improving policies, or maybe even revamping certain systems.
• It’s common to do a follow up verification test on critical fixes to ensure the holes are truly closed.
• The end result is a stronger security posture, the issues found get resolved, and the organization has learned more about its defenses.
• Pen testing isn’t a gotcha exercise, it's a learning process, and the report is the study guide for improving security.

Why the structured process? Following these phases ensures a thorough and safe assessment. It also aligns with industry standard methodologies like the penetration testing methodology frameworks from NIST and OWASP.

By going step by step from recon to exploitation to reporting testers make sure they cover all bases systematically, rather than hacking randomly.

This structured approach is repeatable and scalable, meaning whether you’re testing a small web app or a large corporate network, you have a roadmap to follow.

Types of Penetration Testing

Penetration testing is an umbrella term there are several different types of pen tests depending on the scope and goals. Here are some of the common categories:

External Network Penetration Testing:

• This simulates an attack from outside the organization, targeting its externally facing assets. Think of your public websites, servers, firewalls, and any infrastructure exposed to the internet.
• An external pen test answers the question, What could a hacker on the internet do to us? The tester looks for ways to breach the perimeter for example, finding an open port or vulnerable service in the company’s DMZ demilitarized zone network and exploiting it to get inside.
• Success in an external test might mean the tester managed to access an internal network through a hole in the firewall, or pulled off a SQL injection on a public web app to retrieve customer data.
• This type is crucial because most real attacks start from the outside.

Internal Network Penetration Testing:

• This is the scenario of an insider threat or an attacker who’s already breached the perimeter. The tester operates within the company’s internal network often with standard user credentials or a network jack to plug into.
• The goal is to see how much damage a malicious insider or a malware infection that got in could do.
• For instance, an internal test might reveal that once an attacker is on the office network, they can easily land and expand, perhaps password sharing allows jumping from one compromised machine to another, or sensitive HR files are accessible on an open network share.
• Internal tests often highlight issues like poor network segmentation too much is open once hackers are past the firewall and weak internal passwords or outdated systems that wouldn’t be exposed externally.
• It’s a critical complement to external testing, many breaches occur because an external attacker first phishes an employee, then moves laterally internally.
• An internal pen test shows what could happen at that second stage of an attack.

Web Application Penetration Testing:

• Web apps think customer portals, e-commerce sites, SaaS applications are a huge attack surface these days, so they often get a dedicated type of test.
• In a web app pen test, the focus is on finding vulnerabilities in the application itself things like injection flaws SQL injection, XSS, broken authentication or session management, insecure direct object references IDOR, etc.
• Testers usually follow frameworks like the OWASP Top 10, which is a list of the most critical web app security risks.
• They’ll use tools like Burp Suite to intercept and manipulate web traffic and try to break the app’s logic.
• For example, a tester might attempt to bypass a login or extract another user’s data by tampering with session tokens. Or they might find that an API endpoint has no rate limiting and can be abused.
• The outcome of a web app test is a report on vulnerabilities specific to the web layer, which developers can then remediate patching code, adding input validation, etc.. If your organization builds or heavily uses web software, this type of test is essential.
• Related check out our web application penetration testing services for more on how web apps are assessed, including common web vulnerabilities and fixes.

Mobile Application Penetration Testing:

• Similar in spirit to web testing, but focused on mobile apps iOS, Android and their backends.
• Mobile apps can have issues like insecure data storage, poor authentication, or vulnerabilities in the APIs they talk to.
• A mobile app pen test examines the app binary, how it communicates is data encrypted properly?, and whether someone could reverse engineer or tamper with the app.
• For instance, testers might try to bypass security controls in a banking app or extract sensitive info from a device’s storage.
• Given the prevalence of mobile use, ensuring your mobile apps are secure is very important.
• DeepStrike offers specialized mobile app penetration testing solutions to evaluate mobile specific risks, such as insecure data storage or weak encryption in mobile transactions.

Cloud Penetration Testing:

• As businesses move to the cloud AWS, Azure, GCP, etc., new attack paths emerge.
• Cloud pen testing might involve checking the security of cloud configurations and services for example, testing an AWS environment for things like open S3 buckets, overly permissive IAM roles, or exposed management interfaces.
• Cloud setups can be complex, and a small mistake like leaving a database public or forgetting to restrict an API gateway can lead to a breach.
• Pen testers with cloud expertise will assess how well an organization’s cloud is locked down.
• This often includes attempting to escalate privileges within the cloud like exploiting a misconfigured role to gain admin access to the whole cloud account.
• Cloud pen tests have to be coordinated carefully sometimes with cloud providers’ approval, but they’re critical as cloud misconfigurations remain one of the top causes of data leaks.

Social Engineering Penetration Testing:

• Technology isn’t the only attack vector, humans are often the weakest link. Social engineering tests target the people and processes of an organization. This could be phishing simulations, where a tester sends fake but convincing emails to staff to see if anyone clicks a malicious link or gives up credentials.
• Or it might involve phone pretexting calling helpdesk pretending to be an exec asking for a password reset and even in person attempts like showing up as IT support to see if they can get into a secure area or plug in a malware laced USB drive.
• The aim is to gauge how susceptible employees are to deception and whether security awareness training is effective. For example, a social engineering test might find that 2 out of 10 employees fell for a bogus email attachment, which could have led to a malware infection.
• These findings typically lead to improved training and sometimes process changes e.g., implementing stricter identity verification for password resets.
• Many high profile breaches start with a simple phishing email, so testing this vector is extremely important. For insight into recent trends, see our report on phishing attack trends and statistics.
• It underlines why social engineering tests should be part of your pentesting strategy.

Physical Penetration Testing:

• This is a bit more old school but still relevant for high security environments. It involves attempting to physically breach the organization’s facilities.
• Think sneak into the office scenarios, testers may try to tailgate through doors behind employees, bypass door locks or RFID badges sometimes with lockpicks or cloned badges, find unsecured sensitive documents, or even see if they can walk out with a server.
• The idea is to test physical security controls like locks, alarms, cameras, and personnel procedures.
• A classic example, a tester dresses up as a delivery person and is politely let into a secure area by an employee who doesn’t want to be rude suddenly, the tester is inside with access to network ports or confidential info on desks.
• Physical tests can reveal surprisingly simple vulnerabilities like doors propped open for convenience, or lack of alarm response.
• The outcome usually leads to tightening building security policies, training guards/employees, and reinforcing things like badge rules or visitor sign in processes.

These types of tests can be combined depending on the engagement. For example, a red team exercise is essentially a no holds barred penetration test that blends many approaches. The team might launch a phishing campaign social engineering, then use any foothold gained to pivot internally internal network test, and even try to access physical assets if it’s in scope.

The scope of a pen test is very flexible, it should reflect the biggest risks and concerns of the organization. If you’re unsure what you need, a good penetration testing provider will help define a scope that makes sense e.g., focusing on your web app and an internal simulation for a well rounded evaluation.

Black Box, White Box, Grey Box:

• Another way penetration tests are categorized is by how much information is shared with the tester beforehand.
• In a black box test, the tester starts with zero knowledge not even logins or documentation this emulates an external hacker discovering everything from scratch.
• White box testing sometimes called crystal box means the tester is given full information, access, even source code in some cases, this is more like a code review combined with a pen test, useful for depth and efficiency.
• Grey box is a middle ground the tester might get some insider info, like an account with minimal privileges or a network diagram, to focus efforts while still simulating an attacker who has, say, limited insider access.
• Each approach has its uses black box reveals unseen blind spots, white box can be more thorough in a shorter time.
• Many tests are effectively grey box because organizations will at least share what their systems are. It saves time to not have your consultant waste hours finding the IP address of your website that you could’ve just given them.
• The key is, regardless of knowledge level, the tester tries to think like an attacker at every stage.

For a deeper dive into these approaches, see our explainer on black box vs white box testing which breaks down the pros, cons, and when to use each method.

Penetration Testing vs Vulnerability Scanning: What’s the Difference?

It’s a common question, Why do I need a pen test if I already run vulnerability scans? The terms sometimes get confused, so let’s clarify.

Vulnerability scanning or assessment is an automated process that identifies known vulnerabilities in your systems. Tools like Nessus or OpenVAS will scan your network or website and produce a list of Here are 50 potential issues, with CVSS scores, etc. It’s like a routine health check broad, automated, and generally shallow.

Penetration testing, on the other hand, is a manual, deep dive effort by humans to not just find but exploit vulnerabilities and simulate real attacks. It’s less about quantity of findings and more about demonstrating impact If a hacker chained A, B, and C, they could steal your database.

vulnerability scanning is about breadth and known weaknesses, pen testing is about depth and figuring out unknown attack paths. They complement each other, but one doesn’t replace the other. Here’s a quick comparison:

In practice, both are needed for a robust security program. You might run vulnerability scans monthly to catch easy to find problems and get them fixed. Then do a thorough penetration test quarterly or annually to simulate real attack scenarios and catch the deeper issues.

One analogy vulnerability scanning is like a routine doctor’s checkup quick, automated tests like blood pressure and bloodwork, while penetration testing is like a specialist performing a detailed examination or even a simulated stress test on your body.

The routine checkup may tell you if something obvious is wrong, but the stress test shows how you perform under real pressure and can reveal hidden problems.

To quote a point from security experts a vulnerability scan is not a substitute for a human led pen test, because scanners can miss weaknesses that require context or creativity to find. Conversely, a pen tester will often start with a vulnerability scan as a starting point.

Why manually enumerate all missing patches when a tool can list them?, but then go much further. The combination gives the best coverage.

For more on this topic, see our in depth comparison vulnerability assessment vs penetration testing. It explains common misconceptions and how organizations can balance automated scanning with manual testing for maximum security ROI.

Common Tools Used in Penetration Testing

Penetration testers have a whole arsenal of tools at their disposal. Some are open source and freely available, others are commercial. Importantly, tools don’t make the hacker but they certainly help get the job done faster. Here are some of the common tools and frameworks you’ll often hear about in the pen testing world:

Nmap Network Mapper:

• Nmap is the go to tool for network reconnaissance and scanning. It’s like the Swiss Army knife for mapping a network.
• With Nmap, a tester can discover live hosts, open ports, and services running on those ports by sending crafted packets and analyzing the responses.
• For example, Nmap can quickly tell you These 5 servers are running Windows and have ports 80, 443 open, plus one has port 3389 Remote Desktop open. This information is crucial in figuring out where to focus an attack.
• Nmap can also do more advanced things like OS fingerprinting and version detection figuring out exactly what software version a service is running, which helps in finding known vulnerabilities.

Metasploit Framework:

• Metasploit is a powerful exploitation framework used in many pen tests. Think of it as a toolkit of hundreds of known exploits for various systems that you can deploy at will plus the ability to create and integrate custom exploits.
• Metasploit makes it easier to go from vulnerability found to system owned.
• For instance, if Nmap or a vulnerability scan shows a Windows server is missing a patch for a known SMB vulnerability, a tester can use Metasploit to launch the corresponding exploit and see if it succeeds in getting a shell on that server.
• Metasploit also handles payloads like launching a Meterpreter shell which gives the tester remote control and can manage multiple compromised machines.
• It’s essentially the workhorse for the exploitation phase, enabling testers to simulate what real attackers do but in a controlled way.
• One key reason testers use Metasploit is to streamline and standardize attacks so they don’t have to reinvent the wheel for every exploit.

Burp Suite:

• Burp Suite is the darling of web application testers. It’s an integrated platform with a popular free edition and a more feature rich paid version for finding and exploiting web vulnerabilities.
• Burp’s core is an intercepting proxy you route your browser traffic through Burp, and it lets you intercept, modify, and replay HTTP requests.
• This is hugely useful for testing things like input validation e.g., intercept a form submission and inject some malicious SQL before it hits the server or messing with client side controls like changing a price in an e-commerce order.
• Burp also has an active scanner that can automatically detect common issues like SQL injection, XSS, insecure cookies, etc., by crawling the app.
• Additionally, it provides tools like Intruder for automating customized attacks, e.g., trying a list of passwords, Repeater for manually crafting and re sending requests, and Sequencer for testing randomness in tokens.
• In short, Burp Suite helps an ethical hacker debug and attack web apps in a methodical way. Most web pen test reports with juicy findings probably involved Burp in getting there.

Wireshark:

• Wireshark is a network protocol analyzer basically, it lets you capture and inspect network traffic at a very granular level. If Nmap is looking at the network from 30,000 feet, Wireshark is down in the weeds examining packet by packet.
• Pen testers use Wireshark to sniff network traffic during tests, which can reveal things like unencrypted data being transmitted e.g., passwords in plaintext over HTTP or FTP, or to understand complex protocols.
• For example, if a tester is doing an internal pen test and wants to see if any sensitive info is broadcast on the network, they could run Wireshark and filter for things like SMB traffic or LDAP traffic to see if user credentials are leaking.
• It’s also great for troubleshooting say an exploit isn’t working and you want to see if the packet is reaching the target or what the response is, Wireshark shows you.
• In an age where a lot of traffic is encrypted, Wireshark’s role can be limited unless you’re in a position to capture decrypted traffic, but it’s still invaluable in many scenarios like analyzing why a certain exploit attempt crashed the service by looking at the bytes on the wire.

Nessus and other Vulnerability Scanners:

• While not a penetration testing tool per se, vulnerability scanning tools are often used by pen testers in the early discovery phase.
• Nessus is one of the well known ones along with Qualys, Rapid7 InsightVM, OpenVAS, etc.. These tools will scan a target range and report known vulnerabilities.
• Pen testers use them to get a quick lay of the land a Nessus scan might say Server X is missing MS17 010 patch the one for WannaCry vulnerability or Server Y allows anonymous FTP login.
• That saves the tester time so they can attempt to exploit those findings rather than manually find every minor issue.
• It’s important to note the pen tester will manually validate and often exploit issues rather than just trust the scanner, because scanners can have false positives or might not understand the context which a human can figure out.
• In a pen test report, you might see references to CVE IDs and such those often come from vulnerability scan results combined with the tester’s manual confirmation.
• Essentially, vulnerability scanners are like metal detectors, they help find where the metals vulns are, but you still need a human to dig them up properly and see what treasure or trouble lies beneath.

Kali Linux:

• Rather than a single tool, Kali is a specialized Linux distribution that comes pre loaded with hundreds of pen testing tools including all the ones above and many more.
• Many penetration testers use Kali as their platform during engagements because it’s all set up for offensive security work. Whether it’s wireless cracking tools, web app exploitation scripts, password crackers, or reverse engineering tools Kali has them ready to go.
• It’s maintained by Offensive Security the folks behind OSCP certification and is updated regularly with new tools and exploits.
• So if you ever see a pentester pop open a terminal with a distinctive dragon logo, that’s Kali.
• It’s worth noting that tools evolve new ones keep coming like those to test cloud environments or container security, etc., but the ones listed above have been staples for years and likely will remain so due to their versatility.

Interested in tools? We have a detailed roundup of best penetration testing tools where we dive into more examples like SQLmap for automating SQL injection attacks, Hashcat/John the Ripper for password cracking, OWASP ZAP another web vuln scanner, and more. It’s a great resource if you want to geek out on the offensive toolkit.

Real World Examples of Pen Testing Impact

Penetration testing might sound abstract until you see what a difference it can make in real incidents. Let’s look at a couple of real world scenarios where pen testing played a role in bolstering security or could have helped avoid disaster:

Adobe’s 2013 Data Breach:

• Back in 2013, Adobe Systems was hit with a massive breach attackers stole data from at least 153 million user accounts, including encrypted passwords and password hints. This was a wake up call for Adobe.
• In the aftermath, Adobe doubled down on penetration testing and secure code practices. They started running regular internal and external pen tests on their applications both automated and manual testing, to catch vulnerabilities before release.
• As a result, since that 2013 incident, Adobe has not had a repeat breach of that magnitude.
• Their security team even publicly discussed how they blend automated scanning with manual pen testing to continuously re-secure user data.
• This example shows that pen testing, integrated into a company’s security program, can drastically reduce the chance of another big breach.
• It’s essentially learning from mistakes after getting burned once, Adobe used pen testing to significantly improve their defenses and regain customer trust.

UK National Health Service NHS after WannaCry:

• The WannaCry ransomware attack in 2017 famously affected the NHS, crippling hospital systems and causing appointments to be canceled.
• Post incident analysis showed that the ransomware spread through unpatched vulnerabilities in Windows systems. After this debacle, the NHS realized it needed to proactively find and fix such weaknesses.
• They invested millions in security improvements including regular vulnerability assessments and annual penetration tests across their networks, as guided by the National Cyber Security Centre NCSC.
• The result? The NHS greatly strengthened its cyber defenses and, notably, has not suffered a major ransomware incident on that scale since.
• In this case, pen testing helped identify critical gaps like legacy systems lacking patches, poor network segmentation, etc. so that those could be addressed.
• It also kept the NHS compliant with updated healthcare security requirements and prepared for future threats.
• This example underscores that pen testing is not just a nice to have for critical infrastructure like healthcare, it’s literally part of keeping services running and patients safe from digital threats.

Ongoing Red Team Exercises:

• Many large enterprises think banks, tech giants, etc. have stories where red team pen tests revealed surprising issues.
• For example, a red team at a financial institution once gained domain admin full control of the Windows network in under 3 days due to a series of misconfigurations and one weak password all without being detected by the SIEM security monitoring because they smartly mimicked normal admin activity.
• That exercise led the bank to tighten internal access controls, improve password policies, and upgrade their monitoring to catch similar behavior.
• In another case a retailer’s pen test discovered that their development environment, which wasn’t as well protected, could be used as a bridge to get into production systems so they quickly separated and hardened those environments.
• These kinds of war stories, while often confidential, demonstrate the value of attacking yourself to find what you’d otherwise never know.
• The cost of a pen test engagement is tiny compared to the cost of an actual breach or outage.

In summary, real incidents and case studies consistently show that pen testing pays off. It’s much better to have an ethical hacker find a critical flaw than an adversary. Many organizations only truly appreciate their security gaps after seeing a penetration test report that lays it all out and that’s the first step to fixing the issues and preventing harm.

If you’d like more examples, check out our blog on penetration testing case studies where we share anonymized stories of how different industries benefit from regular pen tests from finance to education to tech companies.

Industry Best Practices and Standards for Pen Testing

Penetration testing isn’t just a wild west of hacking, it’s guided by established best practices and standards to ensure tests are effective, safe, and repeatable. If you’re considering a pen test program, here are some key frameworks and principles to know:

Follow Established Methodologies:

• Don’t reinvent the wheel. There are well known pen testing methodologies like NIST SP 800 115, OWASP Web Security Testing Guide WSTG, PTES Penetration Testing Execution Standard, and others.
• NIST SP 800 115, for instance, provides a structured approach with phases planning, discovery, attack, reporting and lots of practical guidance on conducting tests and handling results.
• OWASP WSTG is a fantastic resource if your focus is web applications, it lists specific tests for everything from SQL injection to business logic flaws.
• Using these frameworks as a reference ensures you cover all bases and maintain consistency. It’s also something auditors and clients like to hear that your testing aligns with reputable standards.

Scope and Rules of Engagement:

• A best practice for any pen test is to define a clear scope and rules of engagement RoE up front. This means specifying exactly which systems, IP ranges, applications, etc., are in scope for testing and which are off limits.
• Also, define what methods are allowed for example, maybe social engineering phishing is in scope, but not phone calls, or denial of service attacks are excluded to avoid downtime.
• Both the organization and testers should agree on these. The RoE will also address timing when the tests take place, any blackout periods, whether the test is announced or unannounced to the internal teams, and communication channels in case a critical issue or an emergency is found.
• Importantly, ensure legal authorization is in place a signed contract that authorizes the specific testing activities for the specified scope.
• This protects both the tester from being accused of hacking and the company ensuring the tester is liable to act within bounds and keep data confidential.
• Essentially, plan the engagement thoroughly surprises are great for birthdays, not so much for penetration tests.

Combine Manual and Automated Techniques:

• A modern best practice is to use a hybrid approach leverage automated scanning to cover ground, but always include manual testing for deeper analysis.
• Automated tools can quickly find the low hanging fruit, but manual expertise finds the tricky stuff and filters out false positives.
• Good pen testing teams will run vulnerability scans, script some brute force attempts, etc., but then manually validate each finding and spend time trying creative attacks that tools wouldn’t think of.
• This hybrid approach gives the best of both worlds efficiency and thoroughness. It’s also why some organizations opt for Penetration Testing as a Service PTaaS platforms these often combine continuous automated scanning with on demand access to human testers for manual deep dives.
• Regardless of how you do it, ensure your strategy isn’t overly reliant on just tools or just human intuition, the combination is key for comprehensive coverage.

Regular Testing and Retesting:

• Pen testing is not a one and done thing. Security is an ongoing process, so best practices recommend testing at least annually, if not more often for critical systems.
• Many standards, in fact, say perform penetration testing at least once a year and after significant changes.
• For instance, if you undergo a big system upgrade or deploy a new application, you should run a targeted pen test on that rather than waiting till next year’s cycle. Also, after you fix the vulnerabilities found in a test, it’s smart to retest those fixes.
• This can be a follow up engagement or just a validation phase to ensure the patches/config changes truly closed the hole and didn’t introduce new ones.
• Over time, frequent testing helps drive a culture of continuous improvement and if you integrate it into development cycles the DevSecOps approach you catch issues early and often.
• Some organizations with mature security even do ongoing bug bounty programs or hire firms to do continuous penetration testing on their environment, providing near real time feedback on new vulnerabilities.
• The key point is that pen testing is a recurring practice. It’s like exercising. One workout is good, but a regular regimen is where you see real improvement in strength.

Integrate with Development and Operations:

• Pen test findings should feed back into how you build and maintain systems.
• A best practice is to incorporate security testing, dynamic and static analysis, code reviews, etc.
• In the software development lifecycle before things go to production that way, the pen test which often hits prod or a prod like environment becomes more of a final check rather than the first time security is evaluated.
• Dev teams should also be educated on the common findings from pen tests e.g., if your testers frequently find SQL injection, invest in developer training on secure coding and input sanitization. Operationally, use pen tests to evaluate your incident detection and response.
• If the pen testers were poking around for a week and your SOC Security Operations Center didn’t notice, that’s a signal you need to improve your logging, alerting, or response playbooks.
• Some organizations even include the SOC in the loop by running purple team exercises collaborative red+blue team so that the defenders learn from the attackers in real time.
• The endgame is not just to fix individual bugs, but to improve processes and resilience systematically.

Ethics and Confidentiality:

• Penetration testing deals with sensitive stuff. Best practices entail handling any data obtained during a test with strict confidentiality.
• If a tester happens to dump a database of customer info or retrieve some proprietary code, that data is usually immediately encrypted and later destroyed in a secure manner after reporting. Both parties should agree on data handling procedures.
• Ethical conduct also means testers avoid exploiting beyond necessary for instance, if they prove they can access 10 customer records via a vulnerability, they shouldn’t exfiltrate all million records just because.
• They stop at what’s needed to demonstrate the point, to minimize risk. Moreover, if a pen tester stumbles on evidence of someone else having breached it happens sometimes you find traces of a real attacker, they should report it immediately through the proper channels.
• The contract should also cover liability and emergency stop conditions like if something is causing system instability, the test halts.
• Ultimately, a penetration test should be done with a mindset of helping, not embarrassing or harming the client.
• Reputable firms and professionals abide by codes of ethics like those by EC Council or CREST to ensure trust and integrity in how they operate.

Leverage Reports for Risk Management:

• Once you have a pen test report, use it beyond just fixing those few issues. The report can be a valuable risk management tool.
• You can update your risk register with the findings, use it to justify security budget needs the pen test showed we need a better WAF here’s the proof why we should invest, and to inform your security awareness training employees clicked on 2/5 phishing emails in the test we need to address that.
• Also, track metrics over time are your pen test findings reducing in number or severity each year? Ideally, yes, as you mature. If not, it might indicate a need to rethink your approach or perhaps expand scope.
• Regulators and partners might ask for evidence of testing being able to show you do regular pen tests and remediate issues promptly goes a long way in demonstrating due diligence and accountability, boosting your trustworthiness as a business.

In summary, applying best practices turns penetration testing from a one off exercise into a robust component of your security program. By adhering to standards OWASP, NIST, etc., you ensure comprehensive coverage and repeatability. By testing regularly and integrating results, you make continuous improvements.

And by handling tests professionally and ethically, you ensure it’s a positive, safe experience that yields real value and no surprises like unintended outages or data exposures. Penetration testing has been around for decades, and the reason is clear when done right, it’s one of the most direct ways to truly gauge and improve your security posture.

In 2025 and beyond, as threats keep evolving, organizations that embrace these practices will be far better positioned to fend off attacks than those who don’t.

Penetration testing, when done right, is like a fire drill for your cyber defenses. It's better to experience a controlled simulation now than a real fire later. We’ve seen that pen testing can uncover everything from an unlocked side door in your network to an obscure bug in your web app that could have led to a serious breach.

By identifying these issues through ethical hacking, organizations get the chance to fix them on their own terms, not when an attacker forces the issue.

In the threat landscape of 2025, pen testing isn’t a luxury, it's a necessity. New vulnerabilities and attack techniques emerge constantly zero day exploits, supply chain attacks, AI driven hacks, you name it.

Penetration testing keeps you on your toes and aware of where you stand against these threats. It complements other security measures firewalls, antivirus, etc. by adding that real attacker perspective that purely defensive tools can’t provide.

Think of all the high profile breaches in recent years many could have been mitigated or even prevented if the organizations had done thorough pen tests and acted on the findings.

The key takeaways? Pen testing exposes the gaps you didn’t know you had, and drives you to improve. It’s an ongoing cycle test, learn, fix, and repeat. Each cycle makes your security stronger and your team wiser.

Also, it’s not just about technology it’s about people and process. A good pen test will test your detection and response, not just prevention. So you learn to not only block attacks but also spot and react to the sneaky ones that slip through.

If your organization hasn’t done a pen test yet or only does them rarely, now is the time to start making them a regular part of your cybersecurity regimen. Start small if needed, maybe test a critical app or a segment of your network and build up.

Use the results to prioritize your security investments where they matter most. Over time, you’ll likely find that pen testing becomes something you look forward to an opportunity to continually strengthen your defenses and validate the hard work you’ve put into security.

Ready to Strengthen Your Defenses? The threats of 2025 demand more than just awareness, they require readiness. If you’re looking to validate your security posture, identify hidden risks, or build a resilient defense strategy, DeepStrike is here to help.

Our team of experienced practitioners provides clear, actionable guidance to protect your business.

Explore our penetration testing services to see how we can uncover vulnerabilities before attackers do. We offer everything from web and mobile app testing to comprehensive red team engagements and Penetration Testing as a Service PTaaS for continuous security. Drop us a line we’re always ready to dive in and help you fortify your organization’s defenses.

About the Author:Mohammed Khalil is a Cybersecurity Architect at DeepStrike, specializing in advanced penetration testing and offensive security operations. With certifications including CISSP, OSCP, and OSWE, he has led numerous red team engagements for Fortune 500 companies, focusing on cloud security, application vulnerabilities, and adversary emulation. His work involves dissecting complex attack chains and developing resilient defense strategies for clients in the finance, healthcare, and technology sectors.

FAQs

What are the different types of penetration testing?

• Penetration tests can target various aspects of an organization’s security.
• Common types include external network testing simulating an outside hacker attacking internet facing systems, internal network testing simulating an insider or breached scenario to see what damage can be done from within, web application penetration testing focusing on web apps and APIs, often referencing OWASP Top 10 vulnerabilities, mobile app penetration testing assessing iOS/Android apps and their backends, social engineering testing employees with phishing or other scams, and physical penetration testing attempting to breach physical office security.
• Each type addresses a different attack vector together, they provide a comprehensive view of security.
• Many engagements mix and match types based on the organization’s needs.
• See Why penetration testing matters for more on tailoring test types to threats.

How often should we conduct penetration testing?

• At minimum, once a year is a good baseline for a full scope penetration test. However, more frequent testing is recommended for critical systems or rapidly changing environments.
• Industry best practices suggest doing a pen test whenever you have a major change, for example, launching a new web application, making significant infrastructure updates, or after a big migration like moving to cloud.
• Some compliance standards PCI DSS, for instance, require annual tests and additional tests after system changes. Additionally, if your organization is high risk or highly targeted, you might do major tests semi-annually or quarterly.
• In between big tests, many companies also run smaller continuous assessments or use PTaaS platforms for ongoing testing of certain assets.
• The cadence really depends on your risk profile but the trend is toward more frequent testing to catch issues sooner.
• Remember to also re-test after fixes to ensure vulnerabilities are properly closed.

How much does a penetration test cost?

• The cost of a penetration test can vary widely based on scope, complexity, and the provider’s expertise. A simple test on a small network or single application might start around a few thousand dollars.
• A large scale, multi week engagement e.g., a full red team exercise on a corporate network and all its apps can cost tens of thousands. Typical range roughly $5,000 up to $100,000+ for extensive tests.
• Factors influencing cost include the number of IPs/apps in scope, the depth of testing basic vuln assessment vs full exploitation, and whether it’s black box takes more effort or white box.
• Some firms charge a flat fee per project, others by day or by asset. There are also subscription models PTaaS where you pay monthly/annually for continuous testing services.
• While it might seem pricey, remember the cost of a breach is usually far higher. It helps to get a detailed quote or RFP and ensure you’re comparing the value a more expensive test might be far more thorough.
• For budgeting, small businesses might focus on critical assets first to keep costs manageable, whereas enterprises often allocate significant budget to annual pen tests across various divisions.
• For more detail, check out our guide on penetration testing cost which breaks down pricing models and gives tips on scoping a test cost effectively.

What’s the difference between penetration testing and vulnerability scanning?

• In a nutshell, vulnerability scanning is automated and broad, while penetration testing is manual and deep.
• A vulnerability scan using tools like Nessus or Qualys will automatically identify known issues, missing patches, default creds, etc. across many systems and give you a list of potential problems.
• It’s something you might do frequently as a basic hygiene check. Penetration testing, on the other hand, is performed by humans who go further, they verify and exploit vulnerabilities to show the real risk.
• For example, a scanner might flag SQL injection possible on a form, a pen tester will actually use SQL injection to extract data to prove the issue. Scanners can produce false positives or can miss logic flaws pen testers dig into those areas.
• Think of scanning as finding doors and windows left open, and pen testing as actually walking through those doors and seeing what valuable things can be accessed inside.
• Both are important, scans cover a lot of ground quickly, and pen tests dive into the critical areas and provide insight that scanners can’t like chained attacks.
• Also, pen tests usually come with expert analysis and remediation advice, whereas scanner tools give raw outputs.
• Our article on vulnerability assessment vs penetration testing provides a detailed comparison and why you should use both in a complementary manner.

Is penetration testing required for compliance PCI DSS, HIPAA, ISO 27001, etc.?

• Many frameworks either require or strongly recommend penetration testing.
• For example, PCI DSS for payment card data explicitly requires pen testing of your cardholder data environment at least annually and after significant changes.
• ISO 27001 doesn’t outright mandate a pen test, but it implies regular testing as part of technical security controls and risk assessments in practice, organizations seeking ISO 27001 certification will often include annual pen test reports as evidence of control effectiveness.
• SOC 2 compliance Trust Services Criteria expects vulnerability assessment and likely pen testing for the Security principle.
• HIPAA healthcare doesn’t specify it by name, but to address the requirement of regular risk analysis and technical testing of safeguards, many healthcare orgs do pen tests.
• GDPR and other data protection laws suggest that appropriate security measures which for many include pen testing be in place and if there’s a breach, being able to show you were doing pen tests can help demonstrate due diligence.
• Additionally, government and defense contractors often have pen testing requirements through standards like NIST 800 53 or FedRAMP for cloud providers.
• In summary, while not every regulation spells out thou shalt do pen testing, the general trend is that it’s considered a best practice to meet the security expectations of most compliance regimes.
• If you handle sensitive data, you’re safer assuming you need regular pen tests to meet both the letter and the spirit of the laws/standards.
• Always check the specific language for your industry, but even if it’s not explicitly required, doing it will bolster your compliance stance and reporting.

Can penetration testing be automated? What about using AI for pen testing?

• Certain parts of penetration testing can be automated, but a full penetration test cannot yet be done end to end by automation alone.
• We do have automated tools vulnerability scanners, script kiddie tools, even AI powered scanners that can handle the repetitive tasks and find common weaknesses.
• And indeed, there are new solutions some call themselves automated penetration testing or AI driven pen tests which largely run a suite of tools and even attempt some exploits automatically.
• However, the human element is crucial because real attacks involve creativity, adaptability, and context understanding that tools don’t have. For example, a human tester might notice a subtle logic issue in an application workflow that no scanner is programmed to detect.
• Or they might adapt on the fly if exploit A doesn’t work, they’ll try a plan B or C, whereas an automated script might just stop.
• AI can assist for instance, AI might help prioritize targets or sift through large data for patterns, but it’s not at the stage where it replaces an expert.
• In fact, experienced testers use automation as helpers: they automate what can be scanning, brute force, etc. and then focus their energy on analysis and creative exploitation.
• Maybe in the future AI will get closer to human level hacking intuition, but as of 2025, automated pentesting tools are more like advanced vulnerability scanners useful for coverage and speed, but not a substitute for a skilled ethical hacker.
• The best approach is a hybrid one, let automation handle the grunt work and data crunching, while human testers do the heavy thinking and complex attack simulations.
• Our blog on manual vs automated penetration testing delves into this topic, showing examples of what each can and cannot do, and why a combination is typically the most effective strategy.

Will penetration testing disrupt my systems or cause downtime?

• A well conducted penetration test is designed to be safe and minimally disruptive. Professional testers take great care to avoid causing outages or damage.
• For example, they often schedule tests during agreed maintenance windows or low traffic periods to minimize any impact.
• They might avoid certain aggressive techniques if the target is very sensitive for instance, not exploiting a vuln that could crash a production server without explicit permission.
• Most tests start gradually doing passive recon and mild scans and if any instability is observed, the testers will coordinate with you.
• It’s also common to exclude obviously dangerous exploits like ones known to cause system crashes from the scope, or to run them only on staging environments.
• That said, there’s always a small inherent risk after all, you are letting someone poke and prod your systems.
• But the risk is far lower than that of an actual malicious attack, because the tester will stop if something seems wrong and will have a rollback plan.
• They also typically back up any critical data or have you do so, just in case. Communication is key during the test, the team should keep you updated on progress, especially if they’re about to try something potentially risky.
• In practice, serious disruptions from pen tests are very rare, and the benefits of finding vulnerabilities outweigh the slight risk.
• If you have extremely critical systems that can’t have any downtime, those can be tested in more passive ways or during maintenance.
• Always discuss concerns with your vendor, they can tailor the approach for example, do read only tests on databases, or refrain from DoS tests to ensure business continuity.
• Ultimately, remember that real attackers won’t be so considerate, so a little controlled testing now prevents uncontrolled issues later.