What is Vulnerability Scanning?


If you are a cybersecurity veteran, you would know that one of the best ways to prevent a data breach is through vulnerability scanning.

What is Vulnerability Scanning?

To predict how hackers might get into your system, vulnerability scanning is one of the easiest methods to employ. However, vulnerability scanning isn’t solely about detecting vulnerabilities in your environment; instead, it is about remediating and changing your processes to ensure that you prioritize and address vulnerabilities once noticed.

In this guide, you will learn the basics of vulnerability scanning and scanless vulnerability assessment, how it works, tips to best manage your network vulnerabilities, and the best way you can perform vulnerability scanning.

But before going deeper, let’s address this salient issue:

Are Vulnerability Scans Necessary?

Owing to the deep-rooted weakness in technology or systems, many organizations have environments, systems, websites or software weaknesses that make them vulnerable to attack since the day their environment is launched. 

When system compromises occur, it can lead to expensive data breach fines and/or irrevocable brand damage to the breached organizations. Many of these compromises could have been dealt with and prevented if they had performed a test such as vulnerability scans on their environment.

In some cases, an organization becomes vulnerable to attack because they fail to apply a security patch or modify their systems without a proper update of related security protocols.

To prevent a data breach and reduce risk, critical vulnerabilities need to be continuously prioritized, identified, and remediated.

Sometimes, attackers use the same vulnerability scanning tools that organizations rely on to discover network vulnerabilities. But, to get ahead of these attackers, you need to be armed with up-to-date emergent vulnerabilities by constantly running external and internal scans.

What Should You Expect from a Vulnerability Scan?

To start with, a vulnerability scan is a high-level and automated test that searches and reports potentially identified vulnerabilities. For instance, some vulnerability scans can locate over 50,000 unique internal and/or external weaknesses. 

External vulnerability scans are those performed outside of your network (e.g., your network perimeter), and they can identify weaknesses in network structures. An internal vulnerability scan is carried out within your network, and it looks at other hosts on the same network to detect internal vulnerabilities.

To better understand, think of your environment like your home; an external vulnerability scan is a similitude to checking to see if your windows and doors are locked, while internal vulnerability scanning is like checking your kitchen and bedroom doors if they are closed.

Ideally, a vulnerability scan will give you a detailed report of the detected vulnerabilities and references for further study on these vulnerabilities. Often, some tools offer directions on how you can fix the problem.

You should also know that scanning alone is not enough. In fact, that is the belief of many businesses. The report cannot act on its own, which is why you need to work quickly on any discovered vulnerability and ascertain that all security loopholes are fixed. After that, you have to rescan to ensure that the vulnerability has been successfully addressed.

Differences Between Vulnerability Scanning and Penetration Testing

The significant difference between a vulnerability scan and a penetration test is that the former is automated while the latter requires a person digging into your network’s complexities. A vulnerability scan can only search and identify vulnerabilities while a penetration tester will dig deeper to find out the source of any exposure detected.

However, penetration tests and vulnerability scans work together to improve your network security. Vulnerability scans are periodic insights into your network security while penetration tests provide a more thorough examination of your network security.

How Does a Vulnerability Scanner Work?

A vulnerability scanner doesn’t check every network file like antivirus software does. This is why your scanner should be configured to scan specific interfaces, including the internal and external IP addresses for vulnerabilities. 

All vulnerability scans are designed to be non-intrusive so that you can carry out your normal activities while the scan is running in the background. An example is a security professional testing your doorknob to check if it’s strong; such a professional doesn’t need to enter your environment before carrying out his work. 

The duty of a vulnerability scan isn’t to exploit vulnerabilities in your network but to provide a summary of alerts for you to act on. While going through your scan results, you may notice some common vulnerability and exposure numbers that you are unfamiliar with. If your vendor doesn’t provide you with details of such numbers, you can check the National Vulnerability Database (NVD) to help you understand and prioritize the risks.

Tips for Managing Your Vulnerabilities

A vulnerability management plan is vital for managing your network security. The following are the best tips to identify potential and existing weaknesses in your network.

  • Perform External Vulnerability Scans: Your external scans must be performed by a PCI-approved scanning vendor (ASV) to validate your PCI compliance. An external scan by an ASV doesn’t make your organization secure. Still, you have to take prompt action to curb the vulnerability and ensure that you rescan until you confirm that the vulnerability has been addressed. 
  • Perform Internal Vulnerability Scans: Most businesses think that running their PCI scan by an ASV is the only requirement needed to be compliant. However, you have to ensure that you are compliant with internal vulnerability scan requirements by either:
  • Searching online and downloading an open-source internal vulnerability scanning tool. or
  • Purchasing an internal vulnerability scanning tool from another service provider or, perhaps, your ASP.

Take note that your organization is solely responsible for internal vulnerability scanning from the initial purchase/download.

  • Qualified and Individualistic Testing: You should only allow your internal scans to be handled by a qualified and different person from the scanned target. This means the person managing your vulnerability scanner should be capable and different from the person remediating and/or handling any discovered vulnerabilities.
  • Perform Periodic Run of Vulnerability Scans: Ideally, every organization should run quarterly internal and external scans. If your target is just one, it will make a total of eight scans per year (one external and internal per quarter). 

However, many vendors will allow you to run unlimited scanning for a single target. This makes it easier because you can remediate and rescan until the vulnerability is addressed if you fail in the first scan. 

  • Perform Scans after Significant Network Changes: Once you’ve decided to run your scans quarterly, you should perform a scan after every significant change. 

A significant change depends on how your environment is configured, but if you perform any modification or upgrade that could affect the security of the cardholder data environment, such change is significant.

Examples of significant changes include:

  • Transferring your cardholder data to a new server
  • Adding more encryption applications
  • Adding new systems of server components
  • Modifying interfaces
  • Altering Firewall rules
  • Enabling or removing a new system that stores cardholder data
  • Altering network structures


The primary reason why you have to scan your network periodically is that cybercriminals discover new and creative ways to exploit vulnerabilities.

Also, remember that vulnerability scanning and scanless vulnerability assessment isn’t only about reporting located vulnerabilities. It provides an avenue to establish a reliable and repeatable process for fixing weaknesses or problems.

Once a vulnerability scan is completed, make sure you fix any identified vulnerabilities on a prioritized basis. You can commence by prioritizing threats based on the risk and effort needed and then running scans until the results are clean.

If you need help with scanless vulnerability assessment, Vicarius is the ideal software to use. Vicarius is a vulnerability management software that targets cybersecurity officers as well IT managers and operators from the U.S. market.

Photo by Fer Troulik on Unsplash

Written by Kent Weigle

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