Vulnerability Scanning Guide

Vulnerability Scanning Guide
Article by Sumana GangulySumana Ganguly
Last Updated: April 20, 2023

Vulnerability scanning creates the ground for all good cyber security strategies, but it is challenging and complicated. If your organization is starting on its way to increased security, understanding vulnerability scanning is crucial.

This article explains what vulnerability scanning is, why it is essential, and the different types of network vulnerability scanning tools to consider.

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What Is Vulnerability Scanning?

At the most basic level, vulnerability scanning uses software tools to identify and report security issues (also called vulnerabilities) affecting your system.

Vulnerability scanning prevents hackers from gaining unauthorized access to the systems or disrupting your business. Vulnerability scanners have several automated tests at their disposal. They probe and gather information about the systems and identify security holes that hackers could use to steal sensitive information.

When an organization is equipped with this knowledge, it can take action to remediate its security weaknesses. Vulnerability management is the ongoing process of discovering and fixing security weaknesses.

Types of Vulnerability Scanning

To really exploit the benefits of vulnerability scanning, you need to understand the different types that exist.

  1. Internal and External Vulnerability Scans
  2. Credentialed and Non-Credentialed Scans

1. Internal and External Vulnerability Scans   

Internal vulnerability scanning is performed in a location with access to the system’s internal network. It helps you protect an existing network from numerous known or unknown vulnerabilities.   

This type of vulnerability scan is best when you need to verify if patches have been deployed and implemented correctly. It also provides a detailed analysis.   

Meanwhile, external vulnerability scanning, also known as perimeter scanning, is done outside of an existing network.   

This type of scan helps recognize any vulnerabilities that pose a threat to services exposed outside the system. Information gathered from external vulnerability scans also includes the ports exposed openly to the internet. It is best processed to identify the level of strength of your external-facing assets.   

Essentially, internal scans can see through security vulnerabilities in a more in-depth manner compared with external scans.  

2. Credentialed and Non-Credentialed Scans   

A credentialed scan is a secured scanning technique where a user must log into a system and look into its vulnerabilities from a trusted source’s perspective. This is performed to evaluate a computer network’s processes and configurations.   

A non-credentialed scan enables you to see vulnerability details from the perspective of an individual who infiltrates a system. In this scanning method, login credentials or system privileges are not required and a user can remotely perform a security check and assessment of misconfigured firewalls and web servers.   

So, what is the primary difference between credentialed and non-credentialed scans?   

Besides the need for user permission, credentialed vulnerability scanning delivers higher accuracy than non-credentialed scanning. The credentialed scanning mechanism offers extended permission to a user for executing scanning operations and, thus, reduces the chance of potential risks from getting into the system.  

Top 5 Vulnerability Scanning Tools

1. Invicti   

Invicti, formerly Netsparker, is an automated vulnerability scanner for detecting, locating and reporting security risks toward a certain web application.   

It is used by developers and security auditing professionals to scan and improve any web application security regardless of the development framework.   

2. OpenVAS   

OpenVAS is an open-source scanning tool featuring more than 50,000 vulnerability tests.   

A constantly updating community, it can conduct authenticated and unauthenticated security tests and large-scale scans. However, there are chances for OpenVAS tests to show some false positive results.  

3. Acunetix   

A highly scalable vulnerability assessment solution, Acunetix offers accurate and fast prioritization of risks detected.    

It is completely automated and can run on multiple platforms, including heavily scripted websites and single-page applications.   

Nevertheless, it may also show some false positives although these occurrences are minimized.  

4. Intruder   

Intruder is a cloud-based security scanning provider that boasts ofan easy-to-use interface. It provides both manual and automated application testing.   

Similar to other scanning solutions, though, it does not guarantee zero false positive results.   

5. Nexpose by Rapid7   

An on-site vulnerability assessment and scanning tool, Nexpose is an excellent choice for small and medium-sized businesses.   

Scoring risks on a scale of one to 1,000 instead of one to 10, it provides users with a more insightful and in-depth report on the exploitability and age of a vulnerability. While some users find this mechanic to be excessive, it helps heighten the accuracy of the reports.   

It offers adaptive security, policy assessment, and remediation reporting. 

How Is Network Vulnerability Scan Different From Penetration Testing?

Vulnerability scanning is often confused with penetration testing, which is another common way of checking the systems for vulnerabilities. However, it is necessary to understand the differences between the two to determine which is more appropriate for your organization.

The advantage of vulnerability scanning is that it can be performed continuously and automatically at a lower cost. It increases the time and expenses overhead, often slowing the projects down. On the other hand, penetration testing is performed on a cybersecurity consulting basis.

Vulnerability scanning and penetration testing have their place, and it is ideal to employ a combination of both if the budget allows. However, vulnerability scanners are suitable for organizations that are just getting started.

This is because penetration testers use vulnerability scanners as part of their offerings. Also, if you can afford to run a penetration test just once a year, you remain exposed to configuration mistakes and new vulnerabilities for the period between.

Hence, vulnerability scanning is a better option for most organizations.

What Are The Different Types Of Vulnerability Scanners?

Different vulnerability scanners perform several security tasks and cover a range of attack scenarios. They can broadly be classified into the following three types:

  1. Network Vulnerability Scanners
  2. Agent-Based Scanners
  3. Web Application Scanners

1. Network Vulnerability Scanners

Network vulnerability scanners scan your systems across the network, sending probes looking for open ports and services. They probe each service for more information, configuration weaknesses, and vulnerabilities.

The way these scanners work varies. For instance, one might install a hardware appliance inside the network or deploy a virtual appliance on a virtual machine, followed by running scans from that machine on the other networks.

One obvious advantage of network vulnerability scanners is that they are quick and easy to set up and install. Maintaining them is a bit of a challenge, as you will have to keep the appliances updated with changes in the network. Also, the more complicated the networks, the higher the number of scanners needed.

2. Agent-Based Scanners

Agent-based scanners are lightweight software scanners on devices. These can run local vulnerability scans and report the results to the central server.

These scanners pick up on a wide range of vulnerabilities, including software weaknesses that do not expose ports or services for remote access. Installing the agents across the digital estate is time-consuming, but it gives you the advantage of reporting back even if it is removed from the network.

Agent-based scanners are the ideal choice for organizations with simple internal networks and the vast majority of their infrastructure in the cloud. However, organizations with fewer budgetary constraints can consider deploying a combination of network vulnerability and agent-based scanners.

3. Web Application Scanners

These are specialized types of vulnerability scanners focusing on identifying web application vulnerabilities. They work by crawling through an application or website in a similar way to a search engine, sending a range of probes to each page or form, and looking for weaknesses.

Many vulnerability scanners carry out web application scanning as part of their offering. It would be best if you looked out whether the scanner can perform authenticated web application scanning. Authenticated scanning is when the application is scanned past the login page. It is done from the perspective of a malicious user or attacker with the credentials to log into the app.

One must remember that web applications are highly complex; therefore, vulnerability scanners cannot effectively identify all the application flaws. They are good at finding specific weaknesses, and human expertise would still be needed to determine the more complex faults manually.

Strategies To Consider The Frequency Of Network Vulnerability Scans

Once an organization has decided which systems should be in scope and what types of scanners would be needed, it is time to start scanning. The next question is what should be your strategy or how frequently you should run the vulnerability scans.

This depends on what you are scanning and why. The following three strategies are for you to consider:

Change Based

Some organizations have a relatively static setup and do not regularly change their systems. On the other hand, fast-moving tech companies deploy code or infrastructure changes almost daily.

With recent developments, there are chances of new vulnerabilities, which one should know about. These could be a new service containing unknown vulnerabilities or a configuration mistake. That is why running a vulnerability scan after every minor change is applied to the systems is a sensible approach.

Hygiene Based

Even if you do not make regular changes to the system, it is imperative to scan them regularly. This is because security researchers frequently find new vulnerabilities in all kinds of software. Public exploit codes exposes them to public disclosure at any time.

Your systems can become vulnerable without any changes, and no software is exempt from this rule. The timelines of the attacks are usually tight, putting the organizations at even greater risk if they cannot react in a reasonable time.

Using a vulnerability scanner at least once a month keeps the systems safe and secure. Not running the scans and fixing issues within a 30–60-day window poses a severe threat to an organization.

Compliance Based

If you are running vulnerability scans to be compliant, then you need to follow specific regulations on how often the scans should be performed.

For instance, PCI DSS requires quarterly external scans on the systems. However, there is no one-size-fits-all guideline, so running a full vulnerability scan monthly is highly recommended. This is also to ensure cloud cybersecurity in an organization.

Businesses can automate much of the vulnerability scanning. However, organizations need resources to keep track of security news and ensure that the latest vulnerabilities do not prohibit effective vulnerability management.

Choosing the appropriate vulnerability scanner that automatically checks your systems reduces the workload and enables the security strategies to be effective.

Vulnerability Scanning Takeaway

Vulnerability scanning feeds into the cyber risk analysis process and helps determine the best controls for a business. The tools must work together to mitigate cyber security risks. It is also essential to learn about penetration testing and how it works.

A professional cybersecurity agency can also help you with this process, so we advise looking for the right agency to partner with for your project.

We’ll find qualified cybersecurity agencies for your project, for free.
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