Penetration Testing vs Vulnerability Scanning Explained

IT and security teams have no shortage of cyber threats to defend against. Identifying weaknesses that criminals can easily exploit should naturally be prioritized. Two types of security testing – vulnerability scanning and penetration testing – are critical tools to help teams identify those weaknesses. While both address vulnerabilities in internally and externally facing systems, there are differences in how they work and when they should be used.

This article will help readers understand:

  • How vulnerability scanners and penetration testing works
  • The benefits and shortcomings of each
  • The best use cases for both 
  • How to integrate vulnerability scanning and penetration testing into your cybersecurity strategy

An Overview of Vulnerability Scanning

What Are Software Security Vulnerabilities?

Security vulnerabilities in software are design or coding errors that could allow a malicious hacker to gain access to resources or data, or cause the application to behave in unexpected ways. Unfortunately, software vulnerabilities are common. In 2023, the National Vulnerability Database reported over 28,000 new vulnerabilities in commercial and open source software, up over 15% from 2022. Each is assigned a Common Vulnerabilities and Exposures (CVE) identifier.

What is a Vulnerability Management Program?

Vulnerability management programs are a fundamental defensive cybersecurity activity.

The goal of a vulnerability management program is to proactively identify, evaluate, remediate, and report on known security vulnerabilities in systems and software before attackers have the opportunity to exploit the vulnerabilities. Vulnerabilities are most effectively identified and evaluated through frequent vulnerability scanning exercises.

Why Have a Vulnerability Management Program?

Maintaining a vulnerability management program is a principle requirement of the Payment Card Industry Data Security Standard (PCI DSS). Vulnerability management programs are also a necessary part of conducting a risk assessment, a requirement when complying with security standards and privacy regulations including HIPAA, GDPR, and the California Consumer Privacy Act (CCPA).

What is Vulnerability Scanning?

Vulnerability scanning is an automated process of identifying publicly known vulnerabilities or CVE, in a company’s IT infrastructure including network, devices, servers, operating systems, web applications, and more. Scan results may include out-of-date software or firmware, vulnerable open source components or applications, and even default passwords left on IoT devices (security cameras, printers, routers, etc.). 

Here’s a breakdown of what a vulnerability scan does:

  • Scans Network and Hosts: A vulnerability scan can examine the target system from both internal and external perspectives. External scans assess the security posture of systems accessible from the internet, such as web servers or public-facing applications. Internal scans focus on devices and systems within the organization’s internal network. Scans can even detect vulnerable “shadow IT” devices outside the control of the IT team.
  • Identifies known vulnerabilities: Scan identify vulnerabilities; known security bugs, missing patches, and misconfigurations  that attackers could exploit. 
  • Produces Reports and Prioritizes Risks: After completing the scan, the vulnerability assessment tool generates a detailed report listing the identified vulnerabilities, along with their Common Vulnerability Scoring System (CVSS) severity score (e.g., critical, high, medium, low), potential impacts, difficulty to exploit, and recommended remediation actions. The report helps organizations prioritize and address the most critical security risks based on their impact and likelihood of exploitation.

In short, a vulnerability scan provides teams with a prioritized list of cyber threats to their organization.

Why is Regular Vulnerability Scanning Important?

Since new vulnerabilities are disclosed every day, a system that was secure yesterday could be vulnerable to an attack today. Each time a new vulnerability is disclosed, a race begins between IT/security teams and attackers looking to exploit the vulnerability.  Exploiting many of these can be trivial. Sometimes the researchers who discover them will include a proof of concept or sample exploit to demonstrate the vulnerability. Other times, criminals may develop their own based on the information disclosed describing the vulnerability.

By incorporating regular vulnerability scanning into your cybersecurity strategy, you can significantly improve your overall security posture and protect your valuable data, systems, and reputation.

Benefits of Vulnerability Scanning

Vulnerability scanning provides organizations with a number of benefits. Here are some of the key ones.

Automation Simplifies Security

Vulnerability scanning is automated; it does not require internal security expertise or additional overhead. Simply schedule the scans for each range of IP addresses and wait for prioritized results. The rest is fully automated.

Proactive Threat Detection

Attacks targeting known vulnerabilities are preventable. Unlike waiting for an attack to happen, vulnerability scans help teams be proactive in their security activities. By systematically searching your systems for known weaknesses, vulnerability scans help teams fix these issues before malicious actors have a chance to use them as entry points.

Continuous Security Monitoring

As noted, cybersecurity threats are constantly evolving, and new vulnerabilities are discovered all the time. Regular vulnerability scans provide a continuous view of the threats your organization faces. By scanning regularly, you can catch new vulnerabilities as they emerge and mitigate risk earlier.


Compared to penetration testing, vulnerability scanning is a more affordable security measure. It’s usually done via automated tools, allowing for frequent scans without a significant investment of time and resources. This makes vulnerability scanning a budget-friendly way to identify and manage security risks.

Helps Meet Compliance Requirements

Many industry regulations and data privacy laws mandate regular risk assessments to proactively identify weaknesses that could threaten your systems and data. Vulnerability scanning is a critical part of a risk assessment. Regular scans demonstrate your commitment to the security of personally identifiable information (PII), personal health information (PHI) and other data that is subject to regulatory requirements such as HIPAA, PCI DSS, GDPR, and others. Vulnerability scanning is also recommended in several security frameworks including NIST 800-53 (Security and Privacy Controls for Federal Information Systems and Organizations) and CIS Controls (Center for Internet Security Controls).

Reduced Downtime and Business Disruption

By proactively addressing vulnerabilities, you can prevent cyberattacks that could result in system outages, data breaches, ransomware attacks, and operational disruptions. This translates to reductions in downtime, incident response costs, and potential reputational damage.

Vulnerability Scanning as a Force Multiplier

Vulnerability scanning tools are automated, which eliminates the need for manual security specialists to spend hours combing through systems for weaknesses. This frees up your IT and security teams to focus on other critical tasks.

Provides an Accurate Baseline 

Vulnerability scans can cover a wide range of internally- and externally-facing systems and applications within your environment. This comprehensive overview helps you gain a good baseline understanding of your overall security posture and identify areas that might require further investigation.

Scan results include CVSS scores to prioritize vulnerabilities based on severity (critical, high, medium, low). This helps you prioritize your remediation efforts to address the most critical systems and weaknesses first.

Limitations of Vulnerability Scanning

Vulnerability scanning is a powerful tool for cybersecurity, but it does have some limitations.

  • Limited scope: Vulnerability scanners rely on predefined checks and sets of known vulnerabilities in popular applications or components. They do not include rules for each of the thousands of vulnerabilities disclosed each year. They might miss entirely new “zero day” vulnerabilities, vulnerabilities for which rules are not present, or those that require manual inspection for detection. 
  • False positives: Scanners can sometimes flag harmless issues (or non-issues) as vulnerabilities, causing teams to waste time and resources investigating them. This can be especially true in complex IT environments.
  • Common attack vectors missed: Not all attacks are executed using known vulnerabilities. Weaknesses including missing authentication, poor encryption, or missing input validation will not be detected through vulnerability scanners. Unauthenticated scans—those conducted without using credentials—will miss vulnerabilities that require privileged access or detailed system information.
  • Point-in-time analysis: Vulnerability scans provide a snapshot of your security posture at a specific time. If a vulnerability is disclosed after the scan, it won’t be detected until the next scan.
  • Unknown exploitability: Not all vulnerabilities are exploitable, particularly if IT or security has put in place compensating controls such as network segmentation or web application firewalls.

However, there is a way to mitigate these limitations. This is where penetration testing comes in. Penetration testing complements vulnerability scans by simulating real-world attacks and uncovering weaknesses that scanners might miss.

An Overview of Penetration Testing

What is Penetration Testing?

A penetration test, or “pen test”, is a simulated cyberattack on your computer system, network, or application. Most organizations employ third-party penetration testers or  “ethical hackers” to conduct the tests. Penetration testers are security professionals who are trained to use commercial and proprietary penetration testing  tools and techniques to attack systems, just as would a malicious attacker. 

Here are some key characteristics of penetration testing:

  • Authorized: Pen tests are conducted with the permission of the organization being tested. This is crucial to avoid legal repercussions and ensure the test doesn’t disrupt normal operations.
  • Simulates real-world attacks: Pen testers use the same techniques and tools employed by malicious hackers, providing valuable insights into how your defenses would fare against a genuine attack.
  • Non-destructive: Pen testers are security professionals who follow a defined methodology and avoid causing any harm to the systems they’re testing. 
  • Remediation guidance: The result of a professional pen test is a prepared report demonstrating the steps a malicious hacker could take to gain access to your systems, elevate privileges, and access systems. It provides prioritized findings, risk ratings, and precise remediation recommendations.
  • External and internal attacks:An external penetration test takes an “outside-in” view of  network security or application security and is designed to identify any exploitable points of entry. A more advanced pen test can focus inside the network to explore what key assets an attacker may be able to access once he or she has gained a foothold. 

What are the Different Types of Penetration Tests?

While many think of penetration testing as an exercise in network security, remember that malicious hackers do not limit their attacks to your externally facing network. Pen testing should be considered for a variety of attack vectors, including:

  •  External pen tests target systems and assets that are accessible from the public internet to identify vulnerabilities and misconfigurations in perimeter assets such as servers, applications, or devices that external attackers could exploit without credentials.
  •  Internal pen tests simulate attacks that originate from within the organization’s network, such as from a compromised employee account, and focus on finding lateral movement, privilege escalation, and other weaknesses.
  • Web application pen tests assess the security of web applications that an organization builds and deploys, including configurations, APIs, authentication methods, permissions/access levels, forms, and session handling.
  • Mobile application pen tests evaluate the security of apps running on iOS, Android, and other mobile platforms as well as how the apps interact with backend systems.
  • Red/Purple teaming are pen tests where defensive teams to work together with offensive teams to test an organization’s ability to identify and contain an attack.

What is the Difference Between Automated and Manual Penetration Testing?

A thorough penetration test is performed by a human using the same tools and techniques as a malicious hacker. Some vendors provide low cost, automated penetration testing. These rely on fixed scripts and fall far short of what is required for a thorough security assessment. They are not capable of the same tactics and techniques used by skilled adversaries and often result in inconsequential findings and unproven “warnings” that internal teams must research to determine if remediation is required.

Why is Regular Penetration Testing Important?

Security is not a permanent state. In most organizations, IT environments change frequently. Systems are patched and reconfigured, users are added and deleted, and new endpoints are deployed. Every time the environment changes, new weaknesses can be exposed.

Regular penetration testing goes beyond the limitations of vulnerability scanning and can reassure teams that patches were successfully deployed and that your systems and data remain secure. It helps you protect your environment against attacks, validate your defenses, and gain a deeper understanding of cybersecurity risks your organization faces. 

Benefits of Penetration Testing

Penetration testing offers a multitude of benefits that contribute to a stronger cybersecurity posture for your organization. Here are some of the key advantages compared to vulnerability scanning:

Uncovering Hidden Weaknesses

Unlike vulnerability scans that rely on predefined checks, pen testing employs a more hands-on approach. Pen testers use their ingenuity and tools to discover weaknesses that automated scanners miss. 

Enhanced Security Posture

By identifying these weaknesses through regular pen tests, teams can proactively address risks before malicious actors have a chance to exploit them. This significantly reduces the chance of a successful cyberattack and potential data breaches or ransomware attacks.

Validation of Security Controls

Pen testing acts as a real-world test of your existing security measures. It assesses the effectiveness of your policies, firewalls, intrusion detection systems (IDS), and incident response procedures. By simulating an attack, you can see how your defenses hold up and identify areas where they might need improvement.

More Thorough Results

Pen testers are taught to “think like a hacker”. They use their ingenuity, experience, and various tools to probe your systems for weaknesses. This hands-on approach can uncover vulnerabilities that automated scanners might miss. Scanners rely on predefined checks and databases of known vulnerabilities, but pen testers can think outside the box and identify security misconfigurations, flaws in custom code, and even social engineering vulnerabilities.

Validation of Remediation Efforts

A valuable aspect of pen testing is the ability to retest after vulnerabilities have been addressed. This helps ensure that the remediation efforts were successful and no new vulnerabilities were introduced during the patching process. Vulnerability scans can be re-run as well, but pen testing provides a more comprehensive re-evaluation of your security posture after remediation.

Rules Out False Positives

Automated vulnerability scanners can sometimes flag harmless issues as vulnerabilities, leading to wasted time and resources investigating them. Pen testers can analyze the potential vulnerabilities they discover and determine if they are genuine security risks. This reduces the risk of chasing false alarms and allows you to focus on exploitable issues.

Regulatory Compliance

External and internal penetration testing is a requirement of the PCI DSS ”at least annually and after any significant infrastructure or application upgrade or modification.”  It is also recommended in security frameworks such as NIST 800-53 and CIS Controls, and ISO/IEC 27001 (Information Security Management Systems).

Pen Testing Limitations

Time, cost, and scope are the biggest limitations of penetration testing. Here’s a breakdown of why these limitations exist.

Investment in Time (up to 3 weeks)

Penetration testing is a thorough process. Pen tests need to be scheduled to ensure the availability of talent. Pen testers need time to understand your systems, plan their approach, execute tests, analyze results, and generate a penetration testing report. 

Importantly, the complexity of the system under evaluation can significantly impact the duration of a pen test. A targeted test focusing on a specific system or application will be quicker than a comprehensive test that encompasses your entire network. This is because more complex systems likely have a larger attack surface (more devices, applications, data) and will naturally take longer to test comprehensively. 

The scope of the penetration test also influences the time it takes. 

Penetration Testing Costs

Pen testers are skilled security professionals with a deep understanding of hacking techniques and security best practices. Their expertise is in high demand and consequently commands a premium. Additionally, the cost of a penetration test is directly related to the time spent on the engagement. Longer, larger testing across a broader range of IP addresses is more comprehensive andbetter simulates the behavior of a determined hacker and naturally costs more.


Given the cost and time required, it is not practical to perform a pen test of an organization’s entire IT and application environment. Pen tests are best suited for in depth examination of an organization’s critical systems and applications.

Penetration testing vs Vulnerability Scanning: Which One Do You Need? 

Since pen testing and vulnerability scanning address different needs, the best approach often involves using both methods together. Consider vulnerability scanning as your regular checkup to ensure good security hygiene, and penetration testing as a more in-depth security audit. 

Regular vulnerability scanning identifies easily exploited vulnerabilities targeted by criminals and should be considered “table stakes” in any security program.. It provides a frequent and cost-effective way to identify weaknesses and maintain a baseline understanding of your security posture.

On the other hand, penetration testing is like a deep dive into your security. It’s ideal for:

  • Assets that are critical to an organization’s business goals or that present heightened risk (e.g., systems and applications handling sensitive data or controlling critical functions).
  • Situations requiring a more in-depth evaluation (e.g., before a new system launch).
  • Validating the effectiveness of your existing security controls and incident response capabilities. 

By implementing a layered security strategy that includes both vulnerability scanning and penetration testing, you can significantly improve your organization’s overall cybersecurity posture.

How to Integrate Vulnerability Scanning and Penetration Testing into Your Cybersecurity Strategy

Integrating vulnerability scanning and penetration testing into your cybersecurity program provides a number of benefits and need not be complicated. Here’s how to start:

Set Vulnerability Scanning as the Foundation of Your Cybersecurity Defense Strategy

Criminals understand that many organizations are unaware of known, exploitable vulnerabilities that provide a simple attack vector. Identifying and addressing these weaknesses should be part of every organization’s security program.

  • Depending on your risk profile, conduct vulnerability scans weekly or monthly. This will identify potential weaknesses early and decrease your organization’s exposure to risk..
  • Use the CVSS score for each issue to prioritize remediation based on severity (critical, high, medium, low). Risk rank your assets, then focus on addressing critical and high-risk systems first to mitigate the most pressing cyber threats.
  • After patching vulnerabilities, re-scan to verify successful remediation and identify any new vulnerabilities introduced during the patching process.

Introduce Penetration Testing for Critical Systems

  • Schedule penetration testing at regular intervals for critical systems and applications. Consider quarterly or bi-annually based on your appetite for risk.
  • Align pen testing with specific goals. For example, you might focus on a new system or your web application to identify vulnerabilities in a staging environment before they are exposed to the public.
  • Use pen testing to validate the effectiveness of your security controls and identify areas for improvement. This can include “purple teaming”; testing your ability to detect and respond to an incident while the pen test is in progress.

Encourage Cross-Team Communication and Collaboration

  • Ensure clear communication of vulnerability scan and pen test results across relevant teams (security, IT, development). This fosters collaboration and helps prioritize remediation efforts.
  • Set a policy for patching vulnerabilities based on severity of the vulnerabilities and criticality of systems on which they are found (Mean Time to Remediate, or MTTR). Track progress over time.


Is vulnerability assessment a part of penetration testing?

Not necessarily. Penetration testing may include some vulnerability scanning as part of the initial reconnaissance phase, but it goes beyond that by attempting to exploit the vulnerabilities and assess the potential impact.

What is the typical timeline for penetration testing?

The timeline for a pen test can vary depending on the size and complexity of your IT environment, as well as the scope of the engagement. It typically ranges from a few days to several weeks, with phases like planning, scanning, exploitation attempts, reporting, and retesting after remediation.

What is the cost of pen testing?

The cost of penetration testing can also vary depending on factors like the duration, complexity, and experience level of the pen testing team.While automated pen tests can be less expensive, they are far less useful.

How Defendify Can Help 

If you’re looking for pen testing, vulnerability scanning, or both, Defendify has you covered. Both are available as part of our 13 tools-in-one cybersecurity solution. It’s perfect for those starting out on their cybersecurity journey, more mature organizations looking to up their game, or for those teams that simply don’t want to deal with dozens of disparate tools and vendors. 

Schedule a meeting with one of our security advisors to learn more.

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