Reading scan results
Vulnerability scanning tools compared: network, endpoint and web app scanners
A plain comparison of vulnerability scanning tools: Nessus, OpenVAS, Qualys, Rapid7, Microsoft Defender, ConnectSecure, Nuclei and Burp Suite, and what each is best at.
By Brandon Sooknanan, Founder, Varaxon Technologies · · 5 min read
There is no single best vulnerability scanner. Each tool is built around a way of looking at systems, from the network, from an agent on the device, or from the outside of a web application, and each suits different estates and budgets. This guide compares the scanners we see most often in the exports people send us, in plain terms. We do not sell any of them, and Varaxon Scan Hub reads results from each of the eight tools compared here.
The three kinds of scanner
| Type | How it works | Good at | Misses |
|---|---|---|---|
| Network scanner | Probes hosts over the network, optionally logging in with credentials | Servers, network devices, printers, anything with an IP address | Laptops that are off the network during the scan; deep web app logic |
| Endpoint agent | Software on each device reports installed software and settings | Laptops and remote workers, continuous results without scan windows | Devices that cannot run an agent, such as switches and appliances |
| Web application scanner | Crawls a site or API and tests requests and responses | Injection flaws, cross-site scripting, insecure headers, exposed admin pages | Operating system patches and anything not exposed through the app |
Network vulnerability scanners
Tenable Nessus
The most widely used standalone scanner. Quick to install, a very large plugin library and clean, consistent results. Nessus Essentials is free for up to 16 IPs; Nessus Professional is a paid single-user annual licence. Larger estates usually move to Tenable's platform products. See how to read a Nessus scan report.
Greenbone OpenVAS
The leading open-source option, free in the Greenbone Community Edition with no target limit. Capable, but more work to install and tune, and its results need more filtering. Our OpenVAS vs Nessus comparison goes into detail.
Qualys VMDR
A cloud platform that combines scanner appliances, cloud agents and asset inventory, with its own risk scoring on top of CVSS. Strong for large and distributed estates and common in regulated industries. Priced per asset, usually through a sales conversation.
Rapid7 InsightVM and Nexpose
InsightVM is Rapid7's cloud-managed platform with scan engines and agents; Nexpose is the on-premises product it grew from. Both add Rapid7's own risk score and remediation project tracking. Priced per asset.
Endpoint and MSP-focused tools
Microsoft Defender Vulnerability Management
Built into Microsoft Defender for Endpoint, it reports software vulnerabilities and weak settings from devices already onboarded to Defender, with no separate scanner to deploy. A natural choice for Microsoft 365 shops; some features need an add-on licence. It only sees devices running the Defender agent.
ConnectSecure
A multi-tenant vulnerability and compliance scanning platform aimed at MSPs, using agents and network probes, with per-client separation built in. Popular with MSPs who want one console across many small clients.
Qualys, Rapid7 and Tenable also offer agents alongside their network scanners, so the line between the groups is blurring.
Web application and template scanners
Burp Suite
PortSwigger's toolkit is the standard for manual web application testing. Burp Suite Professional adds an automated scanner, and PortSwigger sells a separate product for scheduled scanning at scale. Best in the hands of a tester; less suited to unattended monthly scanning of many sites.
Nuclei
An open-source scanner from ProjectDiscovery that runs community-written YAML templates against web and network services. Very fast and good at finding known CVEs, exposed panels and misconfigurations across many targets. Results depend on which templates you run, and it is not a full replacement for authenticated host scanning.
Open-source alternatives such as ZAP are also widely used for web application testing.
How to choose
- List the assets you must cover. Servers and network gear point to a network scanner; a remote workforce points to agents; public websites and APIs need a web app scanner.
- Check what you already pay for. If you have Microsoft Defender for Endpoint, its vulnerability data may cover your endpoints already.
- Decide how much setup time you have. Open-source tools save money and cost time.
- Count users and clients. Single-user licences suit a consultant; MSPs with many clients need per-client separation.
- Look at the export. You will work with the results every month, so make sure the tool exports complete data (CSV, XML or JSON) rather than only a PDF.
- Run a trial on a real network. Compare finding counts with and without credentials, and how long it takes to get from scan to an action list.
What happens after the scan
Every scanner on this list produces a long list of findings sorted by severity. None of them, in its standard report, combines the CISA KEV catalog, EPSS and CVSS into a single order of work, and few make it easy to show a client what was fixed since last month. That step, from export to a ranked plan and proof of progress, is the same work whichever tool you use. Our guide on turning a scan export into a client report covers it.
We built Varaxon Scan Hub to be scanner-agnostic, so you can keep the scanners you already trust. It reads exports from Nessus, Greenbone/OpenVAS, Qualys, Rapid7, Nuclei and Burp Suite, connects to Microsoft Defender and ConnectSecure, and accepts other scanners' CSV, XML or JSON exports. You can check an export free to see what it reads.
Common questions
What is the best free vulnerability scanner?
For network scanning, Greenbone's OpenVAS is the most complete free option with no target limit. Nessus Essentials is free for up to 16 IP addresses. For web applications, ZAP and Nuclei are free and open source.
Do I need more than one vulnerability scanner?
Often, yes. A network scanner covers servers and devices, agents cover laptops that are rarely on the network, and a web application scanner covers sites and APIs. Many teams also run a second network scanner as a cross-check.
What is the difference between a vulnerability scanner and a penetration test?
A scanner is automated and checks for known weaknesses at scale. A penetration test is a person trying to break in, chaining weaknesses and testing logic a scanner cannot. See our guide on vulnerability scans vs penetration tests.
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