In this chapter, we learned the basics about Vulnerability Assessment and Penetration Testing as well as had an introduction to Nessus.

VA and PT are key types of technical risk assessment, where VA concentrates on finding weaknesses or vulnerabilities in the infrastructure and PT goes to the next level to exploit these vulnerabilities.

Such assessments are carried out as preventive control to identify and mitigate vulnerabilities or out of various compliance requirements. Key activities for such tests include scoping, information gathering, vulnerability scanning, false positive analysis, vulnerability exploitation (Penetration Testing), and report generation. Scoping includes a different approach to testing Blackbox (no information about infrastructure) and Greybox (credentials and details about infrastructure are shared).

In this chapter, we also got an introduction to Nessus as one of the widely-used vulnerability scanners. It uses security checks, called plugins, against which vulnerabilities are identified during a scan. The key plugin family includes Windows, Linux, Solaris, Cisco, and Databases. Over the years, Nessus has added features such as configuration and compliance checks, apart from the primary functionality of the vulnerability scanner.

Nessus can be installed on all the major operating systems and detailed steps for installing Nessus on Windows 7 and Linux OS—along with the prerequisites—are mentioned in this chapter.

During initial setup, the initial administrator account is created to log in to Nessus as the administrator, and based on the requirement, the home or professional feed is activated.

This is followed by updating the plugin. The option to update plugins offline is also explained. Nessus offers a user management section to create Nessus users and grant those privileges for future use. Finally, Nessus system configuration settings such as Feed Settings, Mobile Settings, and Advanced Settings were introduced.

In the next chapter, we will learn about scanning the IT infrastructure using Nessus.