C99madshell is software used by hackers to infect your computer with Trojans and viruses. C99madshell is a PHP script that is downloaded as a zipped and base64 encoded stream. To prevent the script from being detected as malware it is wrapped around ten different levels of zip and base64. All the hacker needs to do to run the script is place it on a site where the webserver serves it. Once the hacker gets the script to where it needs to be he just redirects his browser and runs the script.
After running the script the server will send its output to the browser of the hacker. The control panel on the script is very organized with tons of features that allow the hacker to control the server that the script runs on. The best way to protect your computer from this script is to download the c99madshell software apache tools. These tools are generally free and can be found simply by doing an internet search.