Network Vulnerability Assessment Exercise

Any Network Vulnerability Assessment exercise consists of the following steps:

· Finding all the hosts on the network.

· Fingerprinting their Operating systems.

· Detecting open ports on the system.

· Mapping the ports to various network services.

· Detecting the version of the services running.

· Mapping the service version to various discovered security vulnerabilities.

· Verifying if the service on the host is actually vulnerable to an attack or if it has been patched.

The above are also the steps a penetration tester would go through while auditing the security of a network. In my personal experience most administrators allow most hosts to run on the default configuration. This in general has most services running by default and thus making those hosts vulnerable to security breaches. 

In order to scan a network for hosts, port scanning, fingerprinting Operating systems and services, Nmap is a really great tool. Nmap usage is explained in great detail here. However, for scanning hosts for vulnerabilities nothing can beat the capabilities or the flexibility offered by the Nessus vulnerability scanner offered by Tenable Security.

In this video, you will learn how to use the Nessus vulnerability scanner to first discover the hosts on a given network select individual hosts and scan them for various vulnerabilities. You can download the Nessus scanner from here.

Additional Resources:

http://resources.infosecinstitute.com/nmap/

http://resources.infosecinstitute.com/nmap-evade-firewall-scripting/

http://resources.infosecinstitute.com/nessus/

http://resources.infosecinstitute.com/network-scanning-using-nessus/