Running Nessus or OpenVAS Scans

Automated vulnerability scanners probe targets with thousands of checks and match results against CVE databases. They dramatically accelerate assessment but require tuning to reduce false positives.

Nessus runs as a server with a web UI. Policies define what to scan; plugins (100,000+) contain the individual checks. Results are organized by host, severity, and plugin family.

A good basic policy: Basic Network Scan or Advanced Scan. Enable safe checks, configure credentials for authenticated scanning, and set scan timing to avoid disrupting production systems.

Unauthenticated scans see only what is exposed on the network. Authenticated scans (with SSH/SMB credentials) check installed package versions, registry settings, and configuration files — finding far more vulnerabilities.

OpenVAS (now Greenbone Community Edition) is the open-source alternative. It uses the Greenbone Security Manager (GSM) interface and regularly updated NVTs (Network Vulnerability Tests).

Create a Target (host/range), assign a Scan Config (Full and Fast is common), then start a Task. Results appear in real-time; click vulnerabilities for full plugin output and remediation advice.

Scanners output results by severity. Focus on Critical and High first. Read the plugin output carefully — it includes the evidence (banner, version string) that triggered the finding.

Scanners flag issues based on version numbers without confirming exploitability. Always verify critical findings manually — check if the vulnerable component is actually installed and the configuration is truly vulnerable.

Nikto specializes in web server scanning: checks for default credentials, dangerous files, outdated software, and common misconfigurations. It is noisy but fast.

ZAP's active scanner crawls the web app and actively probes every input for injection, XSS, and CSRF vulnerabilities. Run it only against applications you own or have authorization to test.

Vulnerability scanning should be continuous, not one-time. Integrate scanners into CI/CD pipelines for new deployments, and schedule weekly authenticated scans of production systems.

What is the key advantage of an authenticated vulnerability scan?

Nessus and OpenVAS automate vulnerability discovery at scale. Always use authenticated scans for maximum coverage, verify critical findings manually to eliminate false positives, and integrate scanning into continuous security processes rather than treating it as a one-time activity.