Nessus Tool of vulnerability scanning

Nessus is a widely used and highly regarded vulnerability scanning tool designed to identify and assess security vulnerabilities in a network, system, or application. Originally developed by Tenable, Nessus is now available as a commercial product, but there is also a free version, Nessus Essentials, available for non-commercial use. It's one of the most powerful and popular tools for conducting vulnerability assessments due to its wide range of features and its ability to detect a variety of security flaws.

Key Features of Nessus:

1. Comprehensive Vulnerability Scanning:

   • Nessus scans systems, networks, and applications for known vulnerabilities, misconfigurations, missing patches, and other security weaknesses.
   • It includes detection for thousands of vulnerabilities, including those outlined in the Common Vulnerabilities and Exposures (CVE) database.

2. Plugin-Based Architecture:

   • Nessus uses plugins to identify vulnerabilities. There are thousands of plugins that cover a variety of systems, services, and applications.
   • Plugins are continuously updated to keep up with the latest vulnerabilities discovered in the wild, ensuring that Nessus is always up to date with current threats.

3. Advanced Network Discovery:

   • Nessus can perform detailed network discovery to identify live hosts, open ports, running services, and operating systems. This helps create an inventory of devices and systems that are exposed to potential vulnerabilities.

4. Web Application Scanning:

   • Nessus can scan web applications for common vulnerabilities such as SQL injection, Cross-Site Scripting (XSS), and outdated software.
   • It also checks for issues like improper HTTP response headers and insecure configurations.

5. Patch Management and Configuration Auditing:

   • Nessus helps organizations ensure that systems are up-to-date by identifying missing patches, outdated software, and potential configuration errors that could lead to vulnerabilities.

6. Customizable Scanning:

   • Nessus allows users to customize scans to suit their specific environment. You can configure the types of vulnerabilities to search for, adjust the intensity of the scans, and even schedule scans to run at convenient times.
   • It also supports scanning for specific vulnerabilities like those associated with particular systems, applications, or network services.

7. Automated Reporting and Risk Assessment:

   • Nessus generates detailed reports with information about the vulnerabilities discovered, including their severity, potential impact, and remediation suggestions.
   • Reports can be customized, and Nessus assigns a CVSS (Common Vulnerability Scoring System) score to each detected vulnerability, helping users prioritize issues based on their severity.

8. Compliance Checks:

   • Nessus includes compliance checks for various regulatory frameworks and security standards, such as PCI-DSS, HIPAA, CIS benchmarks, and GDPR.
   • This feature helps organizations ensure they meet security and regulatory compliance requirements.

9. Credentialed Scanning:

   • Nessus can perform authenticated (credentialed) scans, which involve logging into systems with valid credentials. This provides a more in-depth scan, enabling Nessus to check configurations, patch levels, and vulnerabilities that would otherwise be invisible in a non-credentialed scan.

10. Integration with Other Security Tools:

• Nessus can integrate with other security tools and management systems for centralized vulnerability management, such as SIEM (Security Information and Event Management) systems and ticketing platforms.

Common Use Cases for Nessus:

1. Penetration Testing:

   • Nessus is widely used in penetration testing to automate the discovery of vulnerabilities and help security professionals find weaknesses in the system that may be exploited by attackers.
   • It is used by ethical hackers to perform quick assessments of targets before manual exploitation.

2. Network Security Audits:

   • Security professionals use Nessus to perform in-depth security audits on networks. Nessus identifies open ports, running services, and potential misconfigurations in network devices, which can help in mitigating risks.

3. Compliance Auditing:

   • Nessus is also used to ensure compliance with security regulations and industry standards. It includes templates and checks for various compliance frameworks such as PCI DSS (for payment systems) and HIPAA (for healthcare data security).

4. Patch Management:

   • Nessus identifies missing patches, outdated software, and systems that require updates, helping organizations with proactive patch management and reducing the risk of exploitation due to unpatched vulnerabilities.

5. Continuous Vulnerability Monitoring:

   • Organizations can use Nessus to schedule regular scans and continuously monitor the security of their systems, ensuring that vulnerabilities are detected and mitigated over time.

How to Use Nessus for Vulnerability Assessment:

1. Installation:

   • Nessus can be installed on Linux, Windows, and macOS systems. For Kali Linux, installation is straightforward through the package manager or by downloading the appropriate version from the Tenable website.
   • Once installed, Nessus must be activated and set up with an account on Tenable's website to receive the latest plugin updates.

2. Configuring a Scan:

   • After logging into Nessus, you can create a new scan by specifying the target systems or networks.
   • You can configure various types of scans such as Basic Network Scan, Web Application Scan, Advanced Scan (with custom plugins), or Compliance Checks.
   • Nessus allows you to provide authentication credentials (for credentialed scans) to increase scan accuracy and depth.

3. Running the Scan:

   • Once the scan is configured, you can launch it. Nessus will scan the specified targets for vulnerabilities, services, and misconfigurations based on the selected scan type.

4. Reviewing Scan Results:

   • Once a scan completes, Nessus will generate a report that highlights the detected vulnerabilities, their severity (using CVSS scores), and provides remediation recommendations.
   • The results can be exported in various formats (HTML, PDF, CSV, etc.) for analysis and reporting.

5. Remediation:

   • After reviewing the findings, system administrators or security teams can use the reports to address identified vulnerabilities. This might include patching software, changing configurations, or enhancing security policies.

Nessus vs. Other Vulnerability Scanners:

• Nessus is known for its accuracy, extensive plugin library, and comprehensive coverage of vulnerabilities. However, it is a paid tool, with a free version available for personal use (Nessus Essentials), which comes with some limitations like the number of IPs that can be scanned.

• OpenVAS, an open-source alternative, offers similar features, but Nessus often outperforms it in terms of speed, usability, and frequent updates.

• Qualys and Rapid7 Nexpose are other commercial vulnerability management tools that offer similar scanning capabilities but may differ in terms of integrations, ease of use, and pricing.