Wazuh vs OpenVAS: Why You Probably Need Both

The Short Answer

"Wazuh vs OpenVAS" is one of the most common searches in open-source security, and it is built on a false premise. They are not competitors. They belong to different tool categories and answer different questions.

In one sentence: Wazuh is a SIEM that tells you what is happening on your systems right now; OpenVAS is a vulnerability scanner that tells you what could be exploited before it happens. Most mature security stacks run both, and Wazuh can even ingest OpenVAS results.

We deploy and maintain both tools in production environments for clients across Europe and beyond. This is the comparison we wish existed when people ask us which one to choose, because the honest answer is usually "neither on its own."

Wazuh and OpenVAS at a Glance

What Wazuh Actually Does

Wazuh is a free, open-source security monitoring platform: threat detection, file integrity monitoring, incident response, and compliance reporting. It is built on the Elastic stack but adds a security-focused layer with agent-based endpoint monitoring, log analysis, and regulatory compliance dashboards.

In practice, Wazuh is the nervous system of a security operation. Agents on endpoints stream logs, file changes, and detected anomalies to a central manager, which correlates them against detection rules and raises alerts. It is the tool an analyst watches to know whether something is wrong now.

Where Wazuh is strong

• Continuous visibility: Real-time monitoring across endpoints, servers, cloud, and applications from one console.
• Compliance built in: PCI DSS, GDPR, HIPAA, and NIST dashboards out of the box, useful for demonstrating control effectiveness to auditors.
• Active response: Can automatically block IPs or isolate endpoints based on configurable rules.
• One agent, many jobs: File integrity monitoring, rootkit detection, log collection, and lightweight vulnerability detection in a single package.

Where Wazuh hurts

• Resource hungry: Elasticsearch wants RAM and disk. Budget 16GB minimum for small deployments, far more as you grow.
• Tuning is not optional: Default rules generate noise. Plan two to four weeks to get false positives down to a level a human can live with.
• Learning curve: The dashboards are powerful and not friendly to non-specialists.

We cover Wazuh in more depth, alongside the rest of our stack, in the open-source security tools we actually use and recommend.

What OpenVAS Actually Does

OpenVAS (now distributed as part of the Greenbone Vulnerability Management suite, or GVM) is an open-source vulnerability scanner. It probes hosts and services against a large, regularly updated feed of network vulnerability tests, then reports what it finds, ranked by severity.

Where Wazuh watches what is happening, OpenVAS goes looking for what could happen. It is a flashlight you point at your own infrastructure on a schedule to find the unpatched services, weak configurations, and known CVEs an attacker would target.

Where OpenVAS is strong

• Cost: Enterprise-grade vulnerability scanning with no per-asset licence fee, which is the headline reason teams choose it over Nessus or Qualys.
• Coverage: Tens of thousands of vulnerability tests, updated frequently from the Greenbone Community Feed.
• Authenticated scans: With credentials, it inspects installed packages and patch levels, not just exposed ports, which dramatically improves accuracy.
• Reporting: Clear, CVSS-scored reports suitable for remediation tracking and audit evidence.

Where OpenVAS hurts

• Setup is painful: Historically the rough edge of the tool. Docker deployments help, but expect to lose half a day on first install.
• False positives: A higher rate than commercial scanners. Findings need human verification before you act on them.
• Speed: Slower than Nessus for equivalent scope. Large network scans take time.
• Weak on web apps: Do not rely on it for web application testing. Pair it with OWASP ZAP or Burp Suite.

The Real Question: Detection vs Prevention

The reason "Wazuh vs OpenVAS" keeps getting asked is that both are open-source, both touch "vulnerabilities," and both end up in the same security budget line. But they sit on opposite sides of the security lifecycle.

OpenVAS is preventative. It reduces your attack surface by finding weaknesses so you can fix them before anyone exploits them. Wazuh is detective. It assumes something will eventually get through and makes sure you see it when it does. Choosing one over the other is like asking whether you need locks or a burglar alarm. You want both, and they make each other more valuable.

How they work together: OpenVAS finds the unpatched server. Wazuh tells you when someone starts probing it. Feed OpenVAS results into Wazuh and a single console shows both your known weaknesses and live activity against them.

Do You Need Both? A Quick Decision Guide

• You have no monitoring at all: Start with Wazuh. Visibility into what is happening on your systems is the foundation everything else builds on.
• You patch reactively and want to get ahead of it: Start with OpenVAS. Knowing your weaknesses lets you prioritise remediation instead of firefighting.
• You are working toward NIS2, DORA, or ISO 27001: You need both. Continuous monitoring and regular vulnerability assessment are explicit or implied requirements in all three.
• You are a small team without a dedicated analyst: Run both, but seriously consider having them managed. The tools are free; the expertise to operate them is not.

What About Wazuh Alternatives?

If Wazuh is too heavy for your environment, the usual open-source alternatives are Security Onion (a packaged detection stack), Graylog (log management with a security focus), and the Elastic Security free tier. None removes the underlying truth: a SIEM is only as good as the tuning and the humans behind it. The tool is the cheap part.

On the scanning side, OpenVAS competes mainly with commercial products (Nessus, Qualys, Rapid7). Among open-source options it is effectively the standard. For web applications specifically, OWASP ZAP is the complement, not a replacement.

How We Deploy Them Together

For most clients we run Wazuh as the central SIEM and endpoint monitoring platform, OpenVAS for scheduled vulnerability scanning, and we route OpenVAS findings into Wazuh so detection and exposure live in one place. Around that core we add MISP for threat intelligence and Suricata for network detection, giving a full open-source security stack at zero licence cost.

The catch, and the reason this comparison matters, is that both tools reward operational discipline and punish neglect. An untuned Wazuh is an alert firehose nobody reads. An unscheduled OpenVAS is a report from last quarter. Deployed and maintained properly, together they deliver capability that rivals commercial stacks costing six figures a year.

If you would rather have that capability without building the in-house expertise to run it, that is exactly the kind of work our cybersecurity team does. Talk to us about what a managed open-source security stack would look like for your environment.

Frequently Asked Questions

Is Wazuh a vulnerability scanner?

Partly. Wazuh includes a vulnerability detection module that compares installed software against CVE feeds, which is useful but lighter than a dedicated scanner. For thorough, authenticated vulnerability assessment you still want OpenVAS or a commercial equivalent.

Can Wazuh and OpenVAS work together?

Yes. Wazuh can ingest OpenVAS scan results so that known vulnerabilities and live security events appear in the same dashboards, which is how we recommend running them.

Is OpenVAS still free?

Yes. OpenVAS ships as part of the Greenbone Community Edition, which is free and open-source. Greenbone also sells commercial appliances with a more complete vulnerability feed and support.

Which should a small business deploy first?

If you have no security monitoring, start with Wazuh for visibility. If you already have some monitoring but patch reactively, start with OpenVAS. For compliance with NIS2, DORA, or ISO 27001, plan to run both.