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Penetration Testing and Vulnerability Scanning: What's the Difference?

How do penetration testing and vulnerability scanning differ? What should a service buyer understand about these to ensure they get value for their investment? This article aims to clarify these concepts and highlight their differences.

Penetration Testing and Vulnerability Scanning Whats the Difference

In the technical assessment of information system security, methods like vulnerability scanning and penetration testing are often used. However, the content of these terms is not always clear, even to experienced security service buyers. Companies offering these services may also label their offerings variably, providing a different service than what one might expect based on the name. So, how do these methods relate or differ from each other?


What is Vulnerability Scanning? 

Vulnerability scanning (sometimes referred to as "vulnerability assessment") involves searching for known issues that could potentially weaken the security level of the target system.

These could include:

  • Known vulnerabilities in software components or operating systems
  • Unintentionally exposed open network ports visible on the Internet
  • Services using weak encryption algorithms 

How Does Vulnerability Scanning Work? 

Vulnerability scanning utilizes software developed to identify vulnerabilities (such as Nessus, Nexpose, Acunetix).


Benefits and Limitations of Vulnerability Scanning 

Scanning is an effective way to review a large number of target systems relatively quickly. It is often cost-effective and affordable, depending on the scanner used. It allows for regular scanning, for example, weekly, monthly, or quarterly. 

Since scanning largely involves automated vulnerability assessments, the tools often produce false positives, where the tool incorrectly identifies something as vulnerable when it is not. Conversely, not all vulnerabilities or weaknesses can be identified purely through automated means. 

Some tools can verify vulnerabilities to a certain extent, but often findings must be reviewed manually. Manual review involves attempting to exploit the reported finding to see what damage it can cause.


There are many types of vulnerabilities:

  • Some enable denial of service with minimal resources
  • Others allow unauthorized access to the system
  • Some provide a route into the internal network through the target system, and so on.

Once the findings have been reviewed and their impact assessed, remediation can begin.


Advantages of Vulnerability Scanning:

+ Cost-effectiveness

+ Speed

+ Ability to automate scanning on a regular cycle 


Disadvantages of Vulnerability Scanning:

- False positives 

- Manual review required 

- Does not verify if a vulnerability is exploitable 

- Does not identify all issues


Vulnerability scanning answers the question:

“What known vulnerabilities, extraneous or outdated services, or configuration errors do our systems (visible to the external network) have?

What is Penetration Testing?

While vulnerability scanning straightforwardly assesses system security and related processes, penetration testing can also evaluate the capabilities for detecting and managing security anomalies.


How is Penetration Testing Conducted?

Vulnerability scanning is often the first phase of penetration testing. The vulnerability data collected during scanning is enriched and developed into exploit codes. A single vulnerability might not allow unauthorized access to a system but may require the simultaneous or chained exploitation of multiple vulnerabilities. 

Exploit codes often aim to gain unauthorized access to an externally visible system that is connected to another system, for example, one located in the internal network. From this foothold, new vulnerability scans can be run on the internal network to identify poorly protected systems to gain another foothold, and so on. Penetration testing bypasses protections layer by layer, advancing the attack from the external network to the internal network. 

Penetration testers usually have a concrete objective (e.g., a target system) they aim to access.


Benefits and Limitations of Penetration Testing

From the client's perspective, penetration testing not only helps assess which vulnerabilities allow unauthorized access but also helps evaluate how well attempts to exploit vulnerabilities can be detected and stopped. 

If you want to find deeply hidden issues in your application or system, penetration testing is a good choice. If your application evolves and updates, regular penetration testing (PTaaS) is an excellent way to ensure continuous security. 

Penetration testers, or ethical hackers, are certified technical security professionals who use their skills to improve system security. Penetration testing can also demonstrate to customers and partners that the application meets industry and legal requirements. Often, software and web applications may need an independent third-party security inspection or assessment. 


Advantages of Penetration Testing:

+ Identifies false positives from scans 

+ Provides a thorough independent expert view of technical security 

+ Includes findings with severity levels and remediation suggestions (plus verification of fixes) 

+ Offers a realistic view of security from a malicious attacker’s perspective 

+ Helps demonstrate compliance 

Regular testing, typically annually or at an agreed cycle, whenever the application receives new updates 

Disadvantages of Penetration Testing: 

- Takes more time 

- Higher costs compared to scanning alone 


In summary, penetration testing can be seen as answering the question:

”What exploitable vulnerabilities do our systems (visible to the external network) have, and do we have the capability to detect if someone is actively trying to exploit them?” 



  • Penetration testing and vulnerability scanning are two different ways to test systems for vulnerabilities. They are often confused with each other. Both have their advantages and are necessary.
  • Vulnerability scanning is largely automated and uses ready-made software to find potential vulnerabilities and report them.
  • Penetration testing is more comprehensive, involving security experts who attempt to find and exploit weaknesses and vulnerabilities. 

Key Differences between Penetration Testing and Vulnerability Scanning:

  • Exploitation of Vulnerabilities:
    Vulnerability scanning detects vulnerabilities. Some scanners try to exploit vulnerabilities, but not all, and they may not exploit everything. Penetration testing attempts to exploit discovered vulnerabilities to gain unauthorized access to an externally visible system, bypassing protections layer by layer, advancing the attack from the external network to the internal network. 
  • Automation vs. Manual Testing: 
    Vulnerability scanning is automated using specialized software. Penetration testing involves a lot of manual testing, using the same techniques that malicious attackers would use, performed by certified professionals. 
  • Testing Regularity and Cycle: 
    Vulnerability scanning is done regularly, often weekly or monthly. Penetration testing is usually done at least annually or whenever the application is developed or updated.
  • Costs:
    Penetration testing requires expertise and continuous professional development. It is more thorough than vulnerability scanning and takes more time, resulting in higher costs.

When procuring services, it is good to be aware of these differences and compare the contents of different service providers' offerings. Make sure you are not buying just a vulnerability scan as penetration testing. A reliable and transparent partner will gladly explain the details of their services. 

Interested in penetration testing? 

Explore our penetration testing services or contact us today for a personalized quote tailored to your needs.