Vulnerability Scanners: Types, Benefits, And Top 5 Scanners

Vulnerability scanners are crucial line of defense protecting web application from the fast evolving and dangerous cyberthreats. This software assesses your network and systems for vulnerabilities and reports the risks associated with them. There are many vulnerability scanning tools available in the industry, but as every organization's need varies, so does the best choice in vulnerability scanners. 

Let’s take a deep dive into learning everything about vulnerability scanning to get your priorities in order and help you select the best fit for your team.

Understanding vulnerability scanners

Vulnerability scanners help you remediate weaknesses and prioritize the process according to their risk level. Once the software completes the scan, it produces a measure of risk associated with identified vulnerabilities and suggests remediation to mitigate the risks. 

When vulnerability scanning is done regularly with proper vulnerability management, it helps protect your organization against new threats emanating from frequent updates in the software. Also, the tool cross-checks with one or more vulnerability databases to identify if there are any known vulnerabilities. 

For instance, NVD, or the National Vulnerability Database, is the U.S. government repository of standards-based vulnerability management data represented using the Security Content Automation Protocol. This data enables the automation of vulnerability management, security measurement, and compliance.

Vulnerability scanners also allow organizations to meet the evolving security standards by monitoring and detecting weaknesses to maintain web application security and network security. Moreover, vulnerability scanning is also one of the first steps in penetration testing.

What is the purpose of vulnerability scanners?

The purpose of vulnerability scanners is to safeguard your organization's security framework against continuously evolving threats. Here is how a vulnerability scanner fulfills its purpose.

• Detects security threats: Continuous scans help you in vulnerability detection and address emerging vulnerabilities both from an external and internal perspective. 
• Discovers unidentified devices: Vulnerability scanners identify rouge machines connected to your network without proper authorization. It helps you protect your network from possible threats that these devices may pose. 
• Verifies network device inventory: Vulnerability scanners help identify all devices in the network with specific details such as device type, version of the OS, hardware configuration, patch level, etc.

What are the types of vulnerability scans?

Whether you have chosen an open-source vulnerability tool or a licensed security scanner, there are different types of vulnerability scans that you can perform with them. The type of vulnerability scan depends upon the scope, environment, and other factors.

One can classify them into the these types:

External vulnerability scan vs. internal vulnerability scan

External vulnerability scans help companies identify and fix problems that expose their network to attackers. These scans are performed from outside the organization's network, including all endpoints, web applications, ports, and more.

The adoption of the cloud has fueled the need for external vulnerability scanning as the presence of misconfigurations and insecure databases has largely increased.

Internal vulnerability scans allow you to tighten the security of applications and systems, mainly from the inside of your enterprise's network.

These scans help you detect the security vulnerabilities that hackers may use for their advantage once they have penetrated through the external defense. These scans also assist in identifying the threat posed by malware or insider threats modeled by disgruntled employees or contractors. 

There are standards such as the Payment Card Industry Data Security Standard (PCI-DSS), which mandates both internal and external vulnerability scans quarterly, as well as when new updates are installed, network topology changes or firewall rules are modified. Here, you must use tools from a PCI-approved scanning vendor (ASV) that adheres to PCI DSS requirement 11.2.2 to perform your external scans. 

Unauthenticated vulnerability scans vs. authenticated vulnerability scans

Unauthenticated vulnerability scans explore and detect services open on a computer over a network by sending packets on their open ports. It determines the version of the operating system, the software's version behind respective services, open file shares, or any other available information without authentication.

Following that, scanners cross-check with the vulnerability database and identify vulnerabilities most likely to be present. 

Authenticated vulnerability scans accumulate more detailed information on the version of the operating system (OS) and software installed by using login credentials to deliver comprehensive information about the system's vulnerabilities.

Sometimes, it’s possible that some programs might not be accessible over the network but can still divulge vulnerabilities exposed to other attack vectors, such as, opening malicious web pages or maliciously crafted files.

To manage such vulnerabilities, some vulnerability assessment solutions deploy lightweight software agents on computers to get a complete picture of an organization's cybersecurity landscape.

Comprehensive vulnerability scans vs. limited vulnerability scans

Comprehensive vulnerability scans explore, examine, and identify new vulnerabilities across every device managed on the network. These include servers, desktops, laptops, virtual machines, mobile phones, containers, printers, firewalls, switches, and more.

Here, you get a complete scan report on the operating system installed, user account information, and open ports, among other things. Comprehensive vulnerability scanning may use a lot of bandwidth, but the plus is, that it doesn't leave any risk overlooked.

Limited vulnerability scans primarily focus on particular devices like a server, workstations, or software. These scans are done to obtain a highly specific security posture of the tools and protect them better against possible risks.

How does a vulnerability scanner work?

Vulnerability scanners work by a three-step mechanism that converges toward your organization's goal of identifying the vulnerabilities and the risk that they may pose. These three mechanisms collaboratively allow you to safeguard your organization's cybersecurity.

1. Detection

The first step of the vulnerability assessment tool is to conduct a vulnerability test for detecting and identifying possible attack surfaces. It enables you to determine the security gaps across your network and fill them before attackers can penetrate it.

2. Classification 

In the second step, the vulnerabilities are classified to help admins prioritize their action course. These vulnerabilities could include missing updates, script errors, or anomalies. while the threats are prioritized based on age and the risk measure. 

3. Remediation 

Generally, vulnerability scanners do not provide a way to address identified vulnerabilities automatically. They are focused more on monitoring and providing details for the admins to take the step further. But some scanners handle configuration errors, thereby saving admin hours of work by reaching multiple devices simultaneously. 

How do you perform a vulnerability scan?

Performing a vulnerability scan requires a standard set of repeatable and scalable processes to address the growing needs of your organization. Execute the steps mentioned below to perform a network vulnerability scan in your organization and set a standard procedure:

Define the scope

It’s essential to define the scope of vulnerability scanning before scheduling it. You need to identify all assets that are a part of the information system of your organization. You can do it with your assets register with additional columns for threats and vulnerabilities to maintain a centralized repository of assets, vulnerabilities, risks, and remediation measures. 

Create a standard procedure

To create a clear and structured methodology of vulnerability scanning, you should have a fixed standard procedure, policies, and a course of action to implement it.

First, you need an official owner who would be responsible for executing the SOP mentioned. Remember, this SOP should be approved by the higher-level authorities and should be according to different compliances like HIPAA or PCI-DSS, for example. 

This standard procedure would define how frequently you should conduct these scans, the type of scans, the usage of software solutions, and the steps after the scan is complete.

Identify the type of vulnerability scan needed

Before going straight into scanning your assets for vulnerabilities, you need to identify which type of scan would yield maximum benefit. 

Configure the vulnerability scan

You can address the configuration of a vulnerability scan based on the general objectives you want to achieve and the system involved.

First, you need to add a list of targeted IP addresses where the courses are hosted in the vulnerability scanning software. You must then select the port range you want to scan and the protocol that you would use. 

The next step defines the targets on the specified IPs, whether it's a database, server, wireless device, or something other. With this, you can make your scan more specific to get accurate results. 

Evaluate the risks associated with the scan

Performing a vulnerability scan can lay a substantial load on the target, forcing it to potentially reboot or suffer downtime.

You should take precautions while scanning production systems and those vital for the organization's operations. It’s best if you perform the scans outside of working hours so the effect on the target is minimal, and there are fewer possibilities of an overload.

Initiate the vulnerability scan

Once you have completed setting the configuration and evaluation of risks, you can run the desired scan. Now the scan's duration depends on a variety of factors like the scope of the scan, its intrusiveness, and more; it may take minutes or hours to complete. 

There are three phases of a vulnerability scan. First is scanning, where the tool will analyze the targets and gather necessary information. Then comes enumeration, when the tool mines for more specific details like ports and services these targets are running. Lastly, the tool will create a map of the vulnerabilities that are present.

Analyze the results

Vulnerability scanning tools will automatically generate a priority list, but you need to check for any false positives or false negatives before prioritizing vulnerabilities for remediation.

You should also consider the effort required to exploit the vulnerability. Hackers will attack those that demand fewer steps and have higher gains for them. Similarly, it will help if you fix those vulnerabilities first that are open to exploitation publicly. 

Create a remediation plan

Once you have analyzed the results, your information security team should collaborate with the IT team to prioritize the remediation process.

It’s best to use the CVSS (Common Vulnerability Scoring System) to prioritize the remediation measures. This standard system helps you quantify the severity of security risks associated with the vulnerability on a scale of zero to 10. Altogether, it would allow you to prioritize and expedite the remediation process. 

It would help if you did not consider a vulnerability fixed after patching, run scans to gain assurance that they do not appear in the reports again. Some vulnerabilities can be complicated, and you may need multiple security patches to fix them.

Top 5 vulnerability scanners

The list below contains real-user reviews from the best vulnerability scanners on the market. To be included in this list, a product must:

• Maintain a database of known vulnerabilities.
• Continuously scan applications for vulnerabilities.
• Produce reports analyzing known vulnerabilities and new exploits.

* Below are the five leading vulnerability scanners from G2's Spring 2024 Grid® Report. Some reviews may be edited for clarity.

1. Wiz

Wiz offers cloud-native vulnerability scanning with a focus on automated scanning. The workload doesn't require any agents or sidecar containers to be deployed. This simplifies deployment and reduces maintenance overhead. 

Reviewers praise Wiz for its user-friendly interface and clear presentation of vulnerability data. Its ability to prioritize vulnerabilities based on context and potential impact, allows users to focus on the most critical issues first. Also, reviewers feel Wiz offers better ongoing product support.

What users like best:

"This is useful for pointout application vulnerabilities for quick remediation. The tool has centralized visibility and oversight, and multiple deployment options; Also UI is easy-to-use and userfriendly.

The most atractive point is it's agentless. I am able to prioritize with no effort from my part and I can customize the rules to fit my organization."

- Wiz Review, Vaibhav S.

What users dislike:

"Wiz often times will release new features that are intended on being "tested" - this can mean that if you don't understand what the value or use case is, they can feel not "production" ready. Some orgs can be turned off by this." 

- Wiz Review, Tony C.

2. Nessus 

Tenable Nessus is a vulnerability assessment solution used by security professionals to perform point-in-time assessments for quickly identifying and fixing vulnerabilities. It also analyzes and detects software flaws, missing patches, malware, and misconfigurations across various operating systems, devices, and applications. 

Reviewers on G2 highlight Nessus's robust automation capabilities and its large library of pre-built scan policies to address various security needs..  It can run pre-configured vulnerability scans without requiring manual intervention, saving time and resources.

Other features include customizable reporting, real-time updates, and group "snooze" functionality. Altogether, it makes vulnerability assessment simple, easy, and intuitive.

What users like best:

"Nessus has one of the largest libraries of vulnerability and configuration checks, covering a wide range of systems, devices, and applications. Despite its comprehensive feature set, Nessus is known for its user-friendly interface, which can help users get up and running quickly.”

 - Tenable Nessus Review, Deepsan V.

What users dislike:

“(Nessus) can be expensive and (suits) larger organization that requires high functionality and support. It is designed with user friendly interface but still it requires a knowledge or training to use it. It consumes more time for scanning.”

- Nessus Review, Lavesh K.

3. Microsoft Defender Vulnerability Management

Microsoft Defender Vulnerability Management is a cloud-based vulnerability management solution offered by Microsoft as part of their endpoint and cloud security products. 

With its integration of Microsoft threat intelligence, it can predict breach likelihoods and prioritize vulnerabilities based on business context and the assessment of devices. Users appreciate the software for not being demanding on CPU/Memory and admire its efficiency and customization options.

What users like best:

“There are many solutions on the market for this purpose, but only few of them are non-demanding for CPU/memory like Microsoft Defender Vulnerability Management. You really cannot notice it's working, no affection at all on system speed, but it gets the job done perfectly. Customization is also great, and can be configured just for your needs very quickly..”

- Microsoft Defender Vulnerability Management Review,  Marko V.

What users dislike:

“The dashboard can be confusing and difficult to use for first-time users; additional training is required to make full use of all of the capabilities. The capabilities of reporting could be increased in order to provide more thorough information about vulnerabilities and the potential impact of those vulnerabilities. The support for third-party goods is severely limited”

- Microsoft Defender Vulnerability Management Review,  Marko V.

4. Orca Security

Orca Security, similar to Wiz, takes an agentless approach. It leverages side-scanning technology to scan your cloud environment without requiring any deployment of agents on workloads.  It is built specifically for cloud environments and understands the intricacies of cloud security and can scan a wide range of cloud assets including virutal machines, containers, serverless functions, and more.

What users like best:

“Agentless Approach and Deep Visibility. It doesn't require the installation of any agents or additional software, that’s why we need just minutes to onboard new accounts to Orca. After onboarding, Orca provides really comprehensive asset discovery, vulnerability scanning, and risk assessment. Also, I am impressed by Orca Security's continuous product development and its dedication to introducing new features.”

- Orca Security Review, Swapnil R.

What users dislike:

“Checking the file that is compromised or miss configurated is hard to see in the dashboard and I'm still not clear about whether it uses sonarqube or just sonar query. there are lots of component which makes it hard to understand.”

- Orca Security, Sujeeth J.

5. Tenable Vulnerability Management

Tenable Vulnerability Management is another product from Tenable that includes the core Nessus scanner within this tool. This goes a step further than vulenrability scanning to risk-based vulenrability management. The tool can be deployed on-premise, cloud or in a hybrid environment. 

Many reviewers find Tenable Vulnerability Management valuable for ensuring adherence to security regulations. Its pre-built compliance checks streamline this process. The platform's detailed reports are appreciated by users.  

What users like best:

“ (I like the) flexibility of the tool, for both internal and external scans. (It) provides good reporting capabilities (and its) easy to establish role based access... (The)Customer support team is great."

- Tenable Vulnerability Management Review, Roger N.

What users dislike:

“Some filters and categories to review your active vulnerabilities are hidden and hard to locate within the dashboard. I had to directly discuss some of my questions with our security compliance engineer, for assistance.”

Tenable Vulnerability Management Review, Esteben G.

Strengthen your cybersecurity now

Choosing the best vulnerability scanner for your organization is paramount, as it would have an enormous impact on your vulnerability assessment and vulnerability management process.

You need software that complements your organization's needs and delivers results as per your expectations. Select the best vulnerability scanner from the above, and make a wise choice in protecting your organization’s cybersecurity from threats and attacks.

Want more? Learn about intrusion detection systems and how they help detect any intruders in your network. 

This article was first published in 2020. It has been updated with new information.