Chris Sullo the inventor of popular website vulnerability scanning tool "Nikto" made another tool "CMS Explorer" to analyse what CMS is in the backbone of a Website.
Visit : http://security.sunera.com/2010/03/cms-explorer-or-whats-that-cms-running.html
Already there is another Mozzila FireFox Add-on Called "Wappalyzer" which can do the same. Check it out at http://wappalyzer.com/
IMPORTANT: All the information in this Blog is for research and academic purposes only! This information is not to be abused! I am not responsible for any damage that you may create using the information you got from this Blog!!
