Nessus is a powerful and widely-used vulnerability scanner developed by Tenable. It helps security professionals identify vulnerabilities in networks, systems, and applications. This guide will take you through the essentials of using Nessus as a remote security scanner, from initial setup to running your first scan and interpreting the results. Whether you’re new to vulnerability scanning or looking to enhance your skills, this tutorial provides a solid foundation for effectively utilizing Nessus.
To begin using Nessus Remote Security Scanner, you’ll need to install the software, configure your initial settings, and then learn how to launch and interpret scans.
This guide will cover setting up Nessus on a common operating system and then dive into the practical steps of remote scanning. Let’s get started.
Install Nessus Scanner
Step 1: Download and Install Nessus
First, you need to download the Nessus scanner. Navigate to the Tenable website and locate the Nessus download page. You will need to register for a Tenable account to download Nessus Essentials, which is free for home use and educational purposes, or access a trial for Nessus Professional if you require more advanced features.
Choose the appropriate installer for your operating system (Windows, macOS, or Linux). For this guide, we’ll focus on a Linux installation, specifically Ubuntu, which is a popular choice for security tools.
Once downloaded, follow the installation instructions provided by Tenable for your chosen operating system. On Ubuntu, this typically involves using the dpkg command in the terminal.
sudo dpkg -i Nessus-version-ubuntu64_amd64.debAfter installation, Nessus service will start, and you can access the Nessus web interface through your browser.
Step 2: Nessus Setup via Web Interface
Open your web browser and go to the address provided after the installation, usually https://localhost:8834. You might see a security warning about the connection not being private, which is normal for a self-signed certificate. Proceed to the website.
Alt text: Command line interface showing the process of cloning the sqlmap repository from GitHub.
You will be prompted to choose your Nessus type (Nessus Essentials, Nessus Professional, etc.). Select the version that suits your needs. For Nessus Essentials, you’ll need to register with your email to receive an activation code.
Follow the on-screen instructions to create an administrator account and enter your activation code if required. Nessus will then download plugins, which are essential for its vulnerability scanning capabilities. This process might take some time depending on your internet connection.
Once the plugin download and compilation are complete, you’ll be logged into the Nessus web interface, and you are ready to configure and run your first scan.
Help Menu and Configuration Options within Nessus Interface
Nessus is primarily managed through its web interface. Explore the interface to familiarize yourself with the different sections:
- Scans: This is where you create, launch, and manage your scans.
- Policies: Policies define the configurations and plugins used during a scan.
- Results: View and analyze the results of your scans, including identified vulnerabilities.
- Users: Manage user accounts and permissions within Nessus.
- Settings: Configure global Nessus settings, such as updates and network settings.
Nessus provides context-sensitive help within the interface. Look for help icons or tooltips next to various options to understand their function. Tenable also offers extensive documentation and support resources on their website.
How to Use Nessus for Remote Scanning
Nessus operates by performing remote scans against target systems. To conduct a remote scan, you need to define a scan target and configure a scan policy.
Example: Basic Remote Scan Configuration
To initiate a basic remote scan, navigate to the “Scans” section in the Nessus web interface and click on “+ New Scan”.
You’ll be presented with a variety of scan templates. For a basic vulnerability scan, you can choose “Basic Network Scan”.
Alt text: Example command in command line illustrating the use of sqlmap with a target URL and parameter for SQL injection testing.
Next, configure the scan settings:
- Name: Give your scan a descriptive name, for example, “Web Server Vulnerability Scan”.
- Targets: Enter the IP address or hostname of the remote system you want to scan. You can specify a single target or a range of targets.
- Policy: Choose a scan policy. The “Basic Network Scan” policy is a good starting point for general vulnerability assessments. You can customize policies for more specific scans later.
For a simple scan, these are the essential configurations. You can explore advanced settings within the policy to fine-tune your scan, such as:
- Discovery: Configure how Nessus discovers hosts and services on the target network.
- Assessment: Select specific plugin families to focus on certain types of vulnerabilities.
- Report: Customize the scan report format and content.
- Schedule: Set up recurring scans to continuously monitor your network.
Once you have configured the scan, click “Save” and then “Launch” to start the remote vulnerability scan.
Understanding Scan Results and Reports
After the scan completes, navigate to the “Results” section to view the findings. Nessus categorizes vulnerabilities by severity level: Critical, High, Medium, Low, and Info.
Click on a specific scan result to see a detailed report. The report will include:
- Vulnerability Name and Description: A clear explanation of the identified vulnerability.
- Risk Information: Severity level and CVSS score, indicating the potential impact.
- Affected Host and Port: Details of the system and service vulnerable.
- Solution: Remediation advice and links to relevant resources for fixing the vulnerability.
Alt text: Command line example demonstrating the use of the –random-agent option in sqlmap to evade Web Application Firewalls.
Use the Nessus reporting features to generate reports in various formats (e.g., HTML, PDF, CSV). These reports are valuable for documenting vulnerabilities, tracking remediation efforts, and communicating security findings to stakeholders.
Nessus Tips for Effective Remote Security Scanning
Optimize Scan Policies
Nessus offers a wide range of scan policies. Experiment with different policies to find the best balance between scan depth and scan time for your environment. For instance, for web application scanning, consider using the “Web Application Tests” policy. For compliance checks, explore policies tailored to specific compliance standards like PCI DSS or HIPAA.
Credentialed vs. Non-Credentialed Scans
Nessus supports both credentialed and non-credentialed scans. Credentialed scans, where you provide Nessus with login credentials to the target system, offer more accurate and comprehensive results as Nessus can access deeper system information. Non-credentialed scans are useful for external assessments but may miss vulnerabilities only detectable from within the system.
Leverage Nessus Automation
For continuous security monitoring, take advantage of Nessus’s scheduling and API capabilities. Schedule scans to run automatically at regular intervals. Use the Nessus API to integrate scan results into your security information and event management (SIEM) or vulnerability management workflows.
Enhance Your Network Security Intelligence
Utilizing Nessus effectively is a crucial step in proactive security management. Combining Nessus with other security tools and practices provides a robust defense strategy.
- Explore other vulnerability management solutions for a comprehensive approach.
- Integrate Nessus with SIEM systems for enhanced threat detection and incident response.
- Stay updated with the latest vulnerability information and Nessus plugins to ensure your scans are effective against emerging threats.
By mastering Nessus remote security scanner, you significantly strengthen your ability to identify and mitigate vulnerabilities, contributing to a more secure IT environment.
