Vulnerability scanning tools (Nessus, OpenVAS) in Cybersecurity - Step-by-Step Execution

Concept Flow - Vulnerability scanning tools (Nessus, OpenVAS)

Start Scan Setup

↓

Select Target Systems

↓

Choose Scan Type

↓

Run Vulnerability Scan

↓

Scan Engine Analyzes Targets

↓

Generate Vulnerability Report

↓

Review & Prioritize Fixes

↓

End

The flow shows how a vulnerability scanning tool like Nessus or OpenVAS runs a scan: setup, target selection, scanning, analysis, reporting, and review.

Execution Sample

Cybersecurity

1. Open tool (Nessus/OpenVAS)
2. Add target IP or hostname
3. Select scan policy (e.g., full scan)
4. Start scan
5. Wait for scan to complete
6. View report

This sequence shows the basic steps to perform a vulnerability scan using Nessus or OpenVAS.

Analysis Table

Step	Action	Tool Behavior	Output/Result
1	Open tool	Tool interface loads	Ready to configure scan
2	Add target IP	Target added to scan list	Target queued for scanning
3	Select scan policy	Scan rules loaded	Scan configured with selected policy
4	Start scan	Tool begins probing target	Scan in progress
5	Scan engine analyzes target	Checks for known vulnerabilities	Finds vulnerabilities or none
6	Generate report	Compiles findings	Report with vulnerabilities and severity
7	Review report	User reads report	Plan fixes based on priority
8	End	Scan session ends	Scan results saved

💡 Scan ends after report generation and review; no further scanning unless restarted.

State Tracker

Variable	Start	After Step 2	After Step 4	After Step 6	Final
Target List	Empty	Contains target IP	Contains target IP	Contains target IP	Contains target IP
Scan Status	Not started	Not started	In progress	Completed	Completed
Report	None	None	None	Generated	Reviewed

Key Insights - 3 Insights

Why does the scan take time after starting?

Because the tool probes the target system for many known vulnerabilities, which requires network communication and analysis (see execution_table step 5).

What does the scan policy affect?

The scan policy determines which vulnerabilities and tests the tool runs, affecting scan depth and duration (see execution_table step 3).

Why is reviewing the report important?

Because it helps prioritize which vulnerabilities to fix first based on severity and risk (see execution_table step 7).

Visual Quiz - 3 Questions

At which step does the tool start actively checking the target for vulnerabilities?

A Step 4

B Step 2

C Step 6

D Step 7

💡 Hint

Look at execution_table row for Step 4 where scan begins.

What is the status of the scan after Step 3?

A Completed

B In progress

C Not started

D Report generated

💡 Hint

Check variable_tracker for Scan Status after Step 3 (between Step 2 and Step 4).

If you add multiple target IPs at Step 2, how does the Target List variable change?

A It remains empty

B It contains all added IPs

C It contains only the first IP

D It resets after each addition

💡 Hint

Refer to variable_tracker for Target List after Step 2.

Concept Snapshot

Vulnerability scanning tools like Nessus and OpenVAS:
- Scan target systems for known security weaknesses
- Require setup: target selection and scan policy
- Perform network probes and checks
- Generate detailed reports with severity levels
- Help prioritize security fixes
- Are essential for proactive cybersecurity

Full Transcript

Vulnerability scanning tools such as Nessus and OpenVAS help find security weaknesses in computer systems. The process starts by opening the tool and adding the target system's IP address or hostname. Next, the user selects a scan policy that defines what tests will run. When the scan starts, the tool probes the target to detect known vulnerabilities. After scanning, it generates a report listing found issues with severity ratings. The user then reviews this report to decide which vulnerabilities to fix first. This step-by-step process ensures systems are checked regularly to improve security.

Practice

1. What is the main purpose of vulnerability scanning tools like Nessus and OpenVAS?

easy

A. To create new software applications

B. To automatically find security weaknesses in systems

C. To manage user accounts and passwords

D. To encrypt data for secure communication

Solution

1. Step 1: Understand the role of vulnerability scanning tools

   These tools scan computer systems to find security weaknesses automatically.

2. Step 2: Compare options with the tool's purpose

   Only To automatically find security weaknesses in systems describes finding security weaknesses, which matches the tool's main function.

3. Final Answer:

   To automatically find security weaknesses in systems -> Option B

4. Quick Check:

   Vulnerability scanning = find security weaknesses [OK]

Hint: Remember: scanning tools find weaknesses automatically [OK]

Common Mistakes:

• Confusing scanning tools with software development tools
• Thinking they manage user accounts
• Assuming they encrypt data

2. Which of the following commands correctly starts a scan using Nessus from the command line?

easy

A. nessuscli scan start

B. openvas --launch

C. scan nessus begin

D. nessus --start-scan

Solution

1. Step 1: Identify correct command syntax for Nessus CLI

   Nessus uses the command line tool nessuscli with subcommands like scan start to begin scans.

2. Step 2: Check each option

   nessuscli scan start matches the correct syntax. Options A, B, and C are incorrect commands. openvas --launch is for OpenVAS, not Nessus.

3. Final Answer:

   nessuscli scan start -> Option A

4. Quick Check:

   Nessus CLI uses 'nessuscli scan start' [OK]

Hint: Nessus CLI commands start with 'nessuscli' [OK]

Common Mistakes:

• Mixing OpenVAS commands with Nessus
• Using incorrect command order
• Assuming simple flags like '--start-scan' work

3. Consider this simplified output snippet from an OpenVAS scan report:

Host: 192.168.1.10
Vulnerabilities found: 3
 - CVE-2021-1234: High
 - CVE-2020-5678: Medium
 - CVE-2019-0001: Low

What does this output tell you?

medium

A. The scan failed to complete on the host

B. The scan found no vulnerabilities on the host

C. The host is fully secure with no risks

D. The host has three security issues with different severity levels

Solution

1. Step 1: Read the scan report details

   The report lists three vulnerabilities found on the host with severity levels High, Medium, and Low.

2. Step 2: Interpret the meaning of vulnerabilities found

   Since vulnerabilities are listed, the host has security issues. It is not fully secure or failed scan.

3. Final Answer:

   The host has three security issues with different severity levels -> Option D

4. Quick Check:

   Vulnerabilities listed = security issues found [OK]

Hint: Vulnerabilities listed means issues found [OK]

Common Mistakes:

• Ignoring the vulnerability count
• Assuming no vulnerabilities means secure
• Confusing scan failure with vulnerabilities

4. You run an OpenVAS scan but get no results even though you know vulnerabilities exist. Which of these is the most likely cause?

medium

A. The target system is offline

B. OpenVAS does not detect vulnerabilities

C. The scan was run without proper credentials or permissions

D. The scan tool is outdated but still shows results

Solution

1. Step 1: Analyze why no results appear despite known vulnerabilities

   Without proper credentials or permissions, OpenVAS cannot access detailed info to find vulnerabilities.

2. Step 2: Evaluate other options

   OpenVAS does not detect vulnerabilities is false; OpenVAS detects vulnerabilities. The target system is offline would cause scan failure, not empty results. The scan tool is outdated but still shows results contradicts showing results.

3. Final Answer:

   The scan was run without proper credentials or permissions -> Option C

4. Quick Check:

   Missing credentials = no vulnerability data [OK]

Hint: No results often mean missing permissions [OK]

Common Mistakes:

• Assuming OpenVAS never detects vulnerabilities
• Confusing offline system with empty results
• Ignoring credential requirements

5. You want to schedule regular vulnerability scans on your network using Nessus. Which approach best ensures continuous security monitoring?

hard

A. Set up automated scheduled scans with email alerts for new vulnerabilities

B. Run manual scans only when a security breach is suspected

C. Disable scans to avoid network slowdowns

D. Scan only once a year during audits

Solution

1. Step 1: Understand best practices for vulnerability scanning

   Regular automated scans with alerts help detect new issues early and maintain security.

2. Step 2: Compare options for continuous monitoring

   Set up automated scheduled scans with email alerts for new vulnerabilities supports continuous monitoring. Options B, C, and D delay detection or reduce security.

3. Final Answer:

   Set up automated scheduled scans with email alerts for new vulnerabilities -> Option A

4. Quick Check:

   Automated scheduled scans = continuous security [OK]

Hint: Automate scans with alerts for best security [OK]

Common Mistakes:

• Waiting for breaches before scanning
• Disabling scans to save resources
• Scanning only during audits