Sec Auditing: Nessus

Introduction

Nessus is one of the most widely used and reliable vulnerability scanning tools in the cybersecurity industry. Developed by Tenable Network Security, it is designed to automate the process of identifying and resolving vulnerabilities within networks, systems, and applications.

• Open-Source Vulnerability Scanners Accessing CVE

Key Features

• Vulnerability Scanning: Nessus excels in scanning for vulnerabilities. It checks for outdated software, misconfigurations, and vulnerabilities that hackers could exploit.

• Comprehensive Vulnerability Database: It has an extensive database of known vulnerabilities, updated regularly to include the latest discoveries in the cybersecurity community.

• Configuration and Compliance Checks: Nessus can review system configurations to ensure compliance with various standards like HIPAA, GDPR, or PCI DSS, making it an invaluable tool for businesses needing to adhere to specific regulatory requirements.

• Customizable Reports: It generates detailed reports that can be customized to cater to different audiences, from technical IT staff to executive management. These reports can prioritize vulnerabilities, suggest remediations, and track vulnerability history.

• High-Speed Discovery: Nessus quickly and accurately identifies assets across your infrastructure, including cloud, mobile, and virtual environments.

How Nessus Works

• Scanning and Assessment: Nessus scans networks, systems, and applications for vulnerabilities. This scanning can be scheduled or performed ad hoc.

• Analysis and Reporting: After the scan, Nessus analyzes the data, correlates it with its vulnerability database, and compiles a report detailing the findings.

• Remediation Guidance: The tool not only identifies vulnerabilities but also provides guidance on how to fix them, which is crucial for IT teams in securing their environments.

Types of Scans

• Basic Network Scan: For detecting vulnerabilities in networks.

• Advanced Scan: Offers more customization and is used for specific environments or scenarios

• Malware Scan: Detects malware on hosts and in web applications

• Compliance Scan: Checks if systems adhere to specific compliance standards.

Deployment

• Nessus Professional: Designed for single-user operation, suitable for consultants or small teams.

• Nessus Manager: Intended for larger teams, offering collaborative features and more advanced options.

Strengths and Limitations

Strengths

• Comprehensive scanning capabilities.

• Regular updates for its vulnerability database.

• User-friendly interface and customizable reporting.

Limitations

• Can be resource-intensive, especially during large-scale scans.

• As with any automated tool, it might produce false positives that need manual verification.

Basic Guide

Using Nessus on Kali Linux involves several steps, as Nessus is a powerful vulnerability scanner used for network security. Here's a general guide on how to get started:

1. Download Nessus: 

   • First, you need to download Nessus. You can get it from the Tenable website. Nessus is not included by default in Kali Linux, so you'll have to download it manually. Choose the appropriate package for Kali Linux (usually a Debian package).

2. Install Nessus:

   • After downloading, you can install Nessus using the dpkg tool. Open a terminal and navigate to the directory where the Nessus package is downloaded. Then, run the command: 'sudo dpkg -i Nessus-<version number>.deb'

   • Replace `<version number>` with the actual version of the file you downloaded.

3. Start the Nessus Service:

   • Once installed, start the Nessus service by running: 'sudo /etc/init.d/nessusd start'

   • This will start the Nessus server.

4. Access the Nessus Web Interface:

   • Nessus is managed through a web interface. Open a web browser and navigate to 'https://localhost:8834'. 

   • The first time you access it, you'll need to set up an account and complete the initial configuration, including setting a username and password.

5. License Nessus:

   • Nessus requires a license. You can register for different types of licenses on the Tenable website. For basic, non-commercial use, a free version called Nessus Essentials is available.

   • Once you have your activation code, enter it into the Nessus web interface to activate your copy of Nessus.

6. Update Nessus:

   • Before you start using Nessus, it’s a good idea to update its plugin database to ensure you have the latest security checks. This can be done from the web interface under the 'Updates' section.

7. Create a Scan:

   • After setting up Nessus, you can create and configure scans to test the security of your network. This is done through the web interface where you can specify targets, set scan policies, and configure other options.

8. Run the Scan and Analyze Results:

   • Run the scan and, once complete, analyze the results. Nessus will provide a report detailing vulnerabilities and potential remedies.

Remember that scanning networks without permission is illegal. Always have authorization before scanning any network with Nessus or any other network scanning tool. Additionally, Nessus is a complex tool with many features, so it's beneficial to refer to the official Nessus documentation or tutorials for in-depth guidance.

Conclusion

Nessus is a powerful tool for identifying and mitigating vulnerabilities in various IT environments. Its versatility, extensive database, and detailed reporting make it an essential tool for cybersecurity professionals. However, effective use of Nessus requires an understanding of network architecture and potential security threats, as the tool serves as a component in a broader cybersecurity strategy.

NEXT: Sec Auditing: Burp Suite