Definition
Nessus is a widely used vulnerability scanner that identifies security weaknesses in computer systems and networks. It performs comprehensive scans by probing for known vulnerabilities, misconfigurations, and missing patches across various operating systems and applications. In practice, Nessus automates the detection of potential security holes before attackers can exploit them. This proactive approach is crucial for maintaining a strong security posture and preventing breaches. For instance, a company might use Nessus to scan its web servers for outdated software that could be exploited. Unlike a penetration test which actively tries to exploit vulnerabilities, Nessus primarily focuses on identification. Understanding Nessus is valuable for roles covered by certifications like CompTIA Security+ and CySA+.