Compare the top vulnerability scanning tools for 2024 including free, open source and SaaS-based vulnerability scanners to help keep your company secure.
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8 Top Vulnerability Scanning Tools for 2024

James Harrison

What is vulnerability scanning? Why do you need it, and how do find the best scanning tool for your needs? Read on to find the best vulnerability scanners for 2024.   

TL;DR 

What is vulnerability scanning? 

Cyber threats are outpacing most organizations’ ability to prevent them, according to the World Economic Forum. While this might make protecting your data and systems seem daunting, there’s a simple, proactive solution to help you safeguard your network and systems – by using a vulnerability scanner. 

Vulnerability scanning tools identify and address cybersecurity weaknesses in your digital infrastructure and systems. When you know where your flaws and weaknesses are, you can fix issues and prevent breaches before they happen. In this article we’ll focus on finding the right solution for your business. If you want a deep dive, check out our Ultimate Guide to Vulnerability Scanning.  

How do vulnerability scanners work? 

Vulnerability scanners search, monitor and assess your systems for known weaknesses. While these tools were originally designed to scan the IPs or host names which users provide, today’s more advanced vulnerability scanning tools can also discover and inventory network access points and all connected devices. By comparing the scan’s findings to known threats, they give you the insight you need to secure your networks and systems. 

Key features of a vulnerability scanner 

At its core, a vulnerability scanner focuses on finding the flaws that hackers look for to breach your systems. That said, different vulnerability scanning tools perform different tasks. To find the right one for your organization, it’s important to identify your needs and understand the benefits of each before diving in. 

Key benefits of using vulnerability scanning tools 

Internal vs. external vulnerability scanning  

Vulnerability scans can be external or internal, depending on which part of your digital assets they’re focused on. External scans target externally-facing IP addresses and their open ports to find vulnerabilities and security flaws in your perimeter and cloud systems. 

Internal vulnerability scans check inside your firewall to find weaknesses in your internal devices such as outdated or unpatched software. For example, MS Office is a big entry point for attackers and can be vulnerable to phishing attacks, which an external scan wouldn’t find.   

Think of it in terms of your home. External vulnerabilities are the open windows, unlocked doors and CCTV blind spots that burglars can exploit to get into your property. Internal vulnerabilities allow the burglar to move from room to room to find and steal your prized possessions.   

In practice, this means you might want to scan an IP for external vulnerabilities to see what could be exploited by an attacker, but you also need to see what the attacker could access on the machine locally.  

8 tried and tested vulnerability scanning tools

Now you’ve got a better idea of what you want and need to scan, here are our top recommendations for vulnerability scanning tools – open source, free and enterprise-grade – from our own Security team. 

Intruder 

Intruder combines automated vulnerability scanning with continuous network monitoring and proactive threat response in one platform, making it easy to secure your ever-changing attack surface. Its speed, versatility, and simplicity make remediation, reporting and compliance easy. It checks for 140,000+ vulnerabilities, automatically synchronizes your cloud environments, and sends you alerts when exposed ports and services change. Intruder proactively scans for emerging threats when new vulnerabilities are discovered and provides reports that are easy for non-security experts to understand, prioritize and action. 

Top features of Intruder 

Who uses it

Because of its ease of use and automated continuous monitoring, Intruder is ideal for tech startups, scale-ups and SaaS businesses with APIs, web apps and assets primarily hosted in the cloud, but without dedicated in-house cyber security or compliance expertise.  

Pricing 

Intruder offers a 14 day free trial and three plans: Essential, Pro, and Premium, with different licenses available for application and infrastructure scanning. You can pay monthly or annually.

Find your weaknesses,
before the hackers do

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OpenVAS 

Open Vulnerability Assessment Scanner (OpenVAS) is a free vulnerability scanning tool. It’s a full-featured tool that provides extensive scanning coverage with the ability to scan for 44,306 vulnerabilities (at the last check). You can find the OpenVAS repository here.  

Top features of OpenVas 

Who uses it

Scanners such as OpenVAS are designed to be used by internal information and security operations center (SOC) teams. OpenVAS provides transparency for senior management to better manage their IT assets and processes. 

Pricing 

OpenVAS is a free, open-source vulnerability scanning tool. 

Probely 

One of the lesser-known vulnerability scanning tools on the list, Probely is still a highly capable platform. Its power lies in how the software prioritizes the most important threats. Probely's dynamic application security testing (DAST) scanner scans your web applications and APIs, claiming to only report security vulnerabilities that matter. This reduces the risk of false positives in reports, which are generated with simple instructions on how to fix the most pressing vulnerabilities.  

Probely | Top vulnerability scanning tools | Intruder

Top features of Probely 

Who uses it

Aimed primarily at developers and DevOps teams who use agile development and want or need to test the apps they’re designing earlier in the development process. Scans can be configured to run frequently and automatically without the need for security professionals.  

Pricing 

Probely offers a lite option, which requires you to purchase credits beyond the 5 free monthly credits included, as well as Pro and Enterprise plans with the option to pay monthly or annually. 

Acunetix 

Acunetix uses a blend of dynamic application security testing (DAST) and interactive application security testing (IAST) to detect over 7,000 vulnerabilities, providing extensive reach to protect sensitive data. This includes hard-to-scan places like password-protected areas and multi-level forms. 

Acunetix | Top vulnerability scanning tools | Intruder

Top features of Acunetix 

Who uses it 

Aimed at the enterprise market, Acunetix is used by financial, military, governmental, educational, and technology companies and institutions, with the majority of its customers having 1000-5000 employees and dedicated security teams. 

Pricing 

Acunetix does not offer a free trial or different pricing plans. You can request a demo or quote on their website. 

Tenable Nessus 

With the ability to scan 65,000 common vulnerabilities and exposures (CVEs), Nessus is one of the more powerful tools on the market and offers great coverage. As enterprise software, it performed highly in our comprehensive analysis. The platform usually gets new checks out faster than other tools, which is why we chose it as one of the scanners that powers our Pro plan.  

Tenable Nessus | Top vulnerability scanning tools | Intruder

Top features of Nessus 

Who uses it

As one of the most popular commercial scanning engines, Nessus is used by 60% of the Fortune 500 who have dedicated cybersecurity consultants and remediation teams. 

Pricing 

A Tenable Nessus Professional license starts at $3,590 per year, but this does not include web application scanning, cloud infrastructure scans, or external attack surface scans. Access to support is not included and costs an additional $400 per year. A 7 day free trial is available. 

Qualys 

Known for its broad scanning capabilities and flexibility, Qualys can scan multiple systems from a single console, including cloud environments and your internal network. You can create custom reports that segment and prioritize data. These reports can be scheduled and generated for more responsive vulnerability management. While the software is advanced, the user experience is quite complex and more suitable for highly technical users.  

Qualys | Top vulnerability scanning tools | Intruder

Top features of Qualys 

Who uses it 

Qualys is primarily aimed at large organizations, such as enterprises, government agencies, and consultancy groups who have the technical expertise to handle an extensive security product. 

Pricing 

Qualys does not offer any pricing information on their website; they require that you get in touch for a quote. A free trial is available for the Enterprise TruRisk Platform. 

Rapid7 

Rapid7 is a live vulnerability and endpoint analytics solution for vulnerability management, designed for companies with large IT networks, especially financial institutions. Its InsightVM solution provides in-depth reports for established security teams and CISOs, but can be overkill for smaller organizations who don’t have the resources and in-house expertise to understand, investigate and fix findings.  

Rapid7 | Top vulnerability scanning tools | Intruder

Top features of Rapid7 

Who uses it 

Rapid7 is aimed squarely at medium sized and enterprise organizations who have the expertise required in-house to setup and maintain and more technical tool.  

Pricing 

Rapid7’s InsightVM is priced based on the number of assets you wish to scan. A free trial is also available.

Nuclei 

Nuclei is an open-source vulnerability scanning engine which is fast, extensible, and covers a wide range of weaknesses. It’s popular with bug bounty hunters, pen testers and researchers who want repeatable checks for serious weaknesses. These experts, working with Nuclei’s team at ProjectDiscovery, combine their knowledge and insights about cutting-edge weaknesses to produce checks extremely fast.  

Nuclei | Top vulnerability scanning tools | Intruder

Top features of Nuclei 

Who uses it? 

Nuclei is simple to get up and running without having to read a lot of documentation, but it’s most popular with bug bounty hunters, penetration testers and researchers who want to produce repeatable checks for serious weaknesses. 

Pricing 

Nuclei is a free, open-source tool.  

How to choose the best vulnerability scanner for your needs 


Looking for a vulnerability scanner that gives you all this and more? Look no further than Intruder for continuous and comprehensive coverage. Effortless attack surface management that ensures you can identify weaknesses in your system before hackers do. Sign up for a free trial to get started. 

Release Date
Level of Ideal
Comments
Before CVE details are published
🥳
Limited public information is available about the vulnerability.

Red teamers, security researchers, detection engineers, threat actors have to actively research type of vulnerability, location in vulnerable software and build an associated exploit.

Tenable release checks for 47.43% of the CVEs they cover in this window, and Greenbone release 32.96%.
Day of CVE publish
😊
Vulnerability information is publicly accessible.

Red teamers, security researchers, detection engineers and threat actors now have access to some of the information they were previously having to hunt themselves, speeding up potential exploit creation.

Tenable release checks for 17.12% of the CVEs they cover in this window, and Greenbone release 17.69%.
First week since CVE publish
😐
Vulnerability information has been publicly available for up to 1 week.

The likelihood that exploitation in the wild is going to be happening is steadily increasing.

Tenable release checks for 10.9% of the CVEs they cover in this window, and Greenbone release 20.69%.
Between 1 week and 1 month since CVE publish
🥺
Vulnerability information has been publicly available for up to 1 month, and some very clever people have had time to craft an exploit.

We’re starting to lose some of the benefit of rapid, automated vulnerability detection.

Tenable release checks for 9.58% of the CVEs they cover in this window, and Greenbone release 12.43%.
After 1 month since CVE publish
😨
Information has been publicly available for more than 31 days.

Any detection released a month after the details are publicly available is decreasing in value for me.

Tenable release checks for 14.97% of the CVEs they cover over a month after the CVE details have been published, and Greenbone release 16.23%.

With this information in mind, I wanted to check what is the delay for both Tenable and Greenbone to release a detection for their scanners. The following section will focus on vulnerabilities which:

These are the ones where an attacker can point their exploit code at your vulnerable system and gain unauthorised access.

We’ve seen previously that Tenable have remote checks for 643 critical vulnerabilities, and OpenVAS have remote checks for 450 critical vulnerabilities. Tenable release remote checks for critical vulnerabilities within 1 month of the details being made public 58.4% of the time, but Greenbone release their checks within 1 month 76.8% of the time. So, even though OpenVAS has fewer checks for those critical vulnerabilities, you are more likely to get them within 1 month of the details being made public. Let’s break that down further.

In Figure 10 we can see the absolute number of remote checks released on a given day after a CVE for a critical vulnerability has been published. What you can immediately see is that both Tenable and OpenVAS release the majority of their checks on or before the CVE details are made public; Tenable have released checks for 247 CVEs, and OpenVAS have released checks for 144 CVEs. Then since 2010 Tenable have remote released checks for 147 critical CVEs and OpenVAS 79 critical CVEs on the same day as the vulnerability details were published. The number of vulnerabilities then drops off across the first week and drops further after 1 week, as we would hope for in an efficient time-to-release scenario.

Figure 10: Absolute numbers of critical CVEs with a remote check release date from the date a CVE is published

While raw numbers are good, Tenable have a larger number of checks available so it could be unfair to go on raw numbers alone. It’s potentially more important to understand the likelihood that OpenVAS or Tenable will release a check of a vulnerability on any given day after a CVE for a critical vulnerability is released. In Figure 11 we can see that Tenable release 61% their checks on or before the date that a CVE is published, and OpenVAS release a shade under 50% of their checks on or before the day that a CVE is published.

Figure 11: Percentage chance of delay for critical vulnerabilities

So, since 2010 Tenable has more frequently released their checks before or on the same day as the CVE details have been published for critical vulnerabilities. While Tenable is leading at this point, Greenbone’s community feed still gets a considerable percentage of their checks out on or before day 0.

I thought I’d go another step further and try and see if I could identify any trend in each organisations release delay, are they getting better year-on-year or are their releases getting later? In Figure 12 I’ve taken the mean delay for critical vulnerabilities per year and plotted them. The mean as a metric is particularly influenced by outliers in a data set, so I expected some wackiness and limited the mean to only checks released 180 days prior to a CVE being published and 31 days after a CVE being published. These seem to me like reasonable limits, as anything greater than 6 months prior to CVE details being released is potentially a quirk of the check details and anything after a 1-month delay is less important for us.

What can we take away from Figure 12?

Figure 12: Release delay year-on-year (lower is better)

With the larger number of checks, and still being able to release a greater percentage of their remote checks for critical vulnerabilities Tenable could win this category. However, the delay time from 2019 and 2020 going to OpenVAS, and the trend lines being so close, I am going to declare this one a tie. It’s a tie.

The takeaway from this is that both vendors are getting their checks out the majority of the time either before the CVE details are published or on the day the details are published. This is overwhelmingly positive for both scanning solutions. Over time both also appear to be releasing remote checks for critical vulnerabilities more quickly.

Written by

James Harrison

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