Vulnerability Scanning

Vulnerability scanning is the process of identifying security weaknesses in systems, networks, and applications before attackers do. It’s the first line of defense in proactive cybersecurity used by penetration testers, SOC analysts, and DevSecOps teams to maintain a strong security posture.

This guide gives you technical, hands-on insights into scanning effectively, avoiding false positives, understanding risk scoring, and integrating results into a continuous security workflow.

What Is Vulnerability Scanning?

A vulnerability scanner probes systems for:

• Missing patches or misconfigurations
• Weak or default credentials
• Exposed services and open ports
• Known CVEs (Common Vulnerabilities and Exposures)
• Unsafe protocols or outdated software versions

Goal

Detect vulnerabilities before threat actors exploit them.

Scanning Workflow Overview

Let’s visualize how a vulnerability scan fits into the broader security cycle:

Each phase ensures not only detection but also remediation and validation, a full vulnerability management lifecycle.

Common Scanning Tools

Tool	Type	Usage
Nmap + NSE	Open-source	Network discovery & script-based vulnerability scans
OpenVAS / Greenbone	Open-source	Comprehensive network & host vulnerability scanner
Nessus	Commercial	Enterprise-grade scanning & compliance checking
Qualys	Cloud-based	Continuous vulnerability management
Nikto	Open-source	Web application vulnerability scanning
Burp Suite	Semi-automated	Web app scanning with manual testing integration

Best Practices for Effective Scanning

1. Identify and Classify Your Assets

Before scanning, define:

• IP ranges or domains
• Operating systems and application stack
• Critical vs non-critical systems

tip

Maintain an up-to-date asset inventory to avoid missing shadow IT systems.

2. Use Credentialed Scanning Where Possible

Authenticated scans provide deeper insights:

• Check patch levels and registry configurations
• Identify outdated or vulnerable software
• Evaluate system hardening policies

# Example: OpenVAS with credentials
omp -u admin -w password --xml="<create_target><name>ServerScan</name><hosts>10.0.0.1</hosts><credentials><credential><type>ssh</type><name>root</name><password>toor</password></credential></credentials></create_target>"

note

Always obtain authorization before performing credentialed scans.

3. Combine Tools for Better Coverage

No single tool detects everything. Use multiple sources for confidence.

Each layer adds reliability and cross-verification.

4. Understand CVSS Scoring

Vulnerabilities are often rated using CVSS (Common Vulnerability Scoring System). The base score ranges from 0 to 10 and measures severity.

$$CVSS_{score} = f(Impact, Exploitability, Scope)$$

Severity	CVSS Score	Color
Low	0.1–3.9	🟩
Medium	4.0–6.9	🟨
High	7.0–8.9	🟧
Critical	9.0–10.0	🟥

tip

Prioritize remediation not only by score but also by asset value and exploit availability.

5. Reduce False Positives

False positives waste analyst time and undermine confidence.

How to minimize them:

• Verify results manually (e.g., test endpoints or patches).
• Correlate findings with system logs.
• Disable redundant plugins or outdated detection signatures.
• Regularly update vulnerability databases (e.g., CVE feeds, NVTs).

# Update OpenVAS feed
greenbone-nvt-sync

6. Automate & Integrate Scans in CI/CD

In modern DevSecOps environments, automation is key.

Example workflow:

Tools

GitHub Actions, Jenkins, or GitLab CI can automatically trigger scans during build/test stages.

info

Integrate scanners like Trivy, Snyk, or Dependency-Check for container and dependency scanning.

7. Continuous Monitoring and Reporting

• Schedule weekly or monthly scans for critical infrastructure.
• Track vulnerability trends with dashboards (e.g., Grafana, ELK).
• Generate executive summaries for leadership.

# Example: Scheduled scan using cron
0 2 * * 1 openvas-start --target "Production Servers"

info

Reporting should include vulnerability trends, severity breakdowns, and remediation status.

Quick Math Example — Risk Prioritization Formula

To calculate overall risk score for a vulnerability:

$$Risk = Likelihood \times Impact$$

For example:

• Likelihood = 0.8 (based on exploitability)
• Impact = 0.9 (based on data sensitivity)

$$Risk = 0.8 \times 0.9 = 0.72$$

A score above 0.7 might trigger an immediate patch or containment action.

Real-World Example

Scenario: You’re performing a vulnerability scan on a web application.

Step	Tool	Action
1	Nmap	Identify open ports (80, 443, 8080)
2	Nikto	Run web server vulnerability scan
3	Burp Suite	Test for SQLi, XSS, CSRF
4	OpenVAS	Validate findings at network level
5	Manual	Confirm exploit manually or through PoC

nikto -h https://example.com -output scan_results.txt

Cross-validate Nikto results with OWASP ZAP or Burp to filter false positives.

Final Thoughts

Vulnerability scanning is not a one-time event — it’s a continuous, adaptive process. Combine automated scanning with human validation, integrate it into your CI/CD workflow, and align results with your organization’s threat model.

Key Points Recap:

• Start with accurate asset discovery
• Use both authenticated and unauthenticated scans
• Cross-verify results with multiple tools
• Automate scans and integrate into DevSecOps
• Continuously monitor and report vulnerabilities

“Scanning without remediation is just noise. Make sure every detected issue leads to action.”