Nessus

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Nessus is a network vulnerability scanner.

• developed by Tenable Network Security
• versions:
  • Nessus Manager (on-premises)
  • Tenable Cloud (cloud)
  • Nessus Professional (for smaller networks)
• free to use for home users but paid for on a subscription basis for enterprises
• previously open-source program
  • supplied the source code for many other scanners
• used for vulnerability assessments and regular security audits
• can scan for a variety of different vulnerabilities
• many preloaded scans available
  • Default scans can be performed using the plug-ins from Nessus’s subscription feeds
• custom plug-in can be created using Nessus Attack Scripting Language (NASL)
• Nessus Professional allows remote scanning of hosts
• Nessus Manager and Tenable Cloud can work with locally installed agent software

Example Scan in Nessus Manager

Consider the following agent scan run from Nessus Manager:

• Scan results show most issues are due to lack of patch management

• Looking at the issue marked most critical, we can use the report to determine how significant it really is:

• CVSS metrics are shown on the right
• “Exploitable with” section can show exploits that have been developed
• patching this exploit is a top priority
• can be remediated with Windows Update and scheduling them regularly