Network Vulnerability Assessment Basics

Any Network Vulnerability Assessment exercise consists of the following steps:

1. Finding all the hosts on the network
2. Fingerprinting their Operating systems
3. Detecting open ports on the system
4. Mapping the ports to various network services
5. Detecting the version of the services running
6. Mapping the service version to various discovered security vulnerabilities
   
7. 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 pen 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. We have covered Nmap usage 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 the video below, we 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 vulnerabilites. You can download the Nessus scanner from here.

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Vivek Ramachandran is a security evangelist and has been working in computer security related fields for the past 7 years. In 2007, Vivek spoke at world renowned conferences Defcon (WEP Cloaking Exposed) and Toorcon (The Caffe Latte Attack). The discovery of the Caffe Latte Attack was covered by CBS5 news, BBC online, Network World etc news agencies.In 2006, Vivek was announced as one of winners of the Microsoft Security Shootout contest held in India among 65,000 participants. He has also been a recipient of a Team Achievement at Cisco Systems for his work on 802.1x and Port Security modules on the Catalyst 6500 switches. Currently he spends all of his time maintaining Security- Freak.Net , SecurityTube.Net and is the co-founder of Axonize. Vivek, is a Bachelor in Electronics and Communications Engineering from the prestigious Indian Institute of Technology, Guwahati.You can contact him at vivek[at]securitytube.net