SHELLS_AND_DEFACING

More often than not, we keep hearing about site getting defaced. How exactly does this work? Let’s get a brief overview and how the attack is launched:

Shells:
Shells are a malicious PHP files which you will need to upload to any website,and once you execute it you will get access to its server directly WITHOUT authenticating yourself. The Idea is, you upload the shell to any website so it will be saved on their server and it will give you the access to it.
Uploading a shell: Suppose you want to hack "something.com". So the first thing that you will do is, open up "something.com", and try to find some place from where you can upload the files on the website. There are many such places for example, "file uploads, avatars, resume upload, cooking recipe uploads, upload your photo". So these are the places which will give you an opportunity to upload your shell. All you have to do is, try to upload the shell.php which is located in your computer and click on submit. So suppose you went to the webpage "something.com/submit_resume.php" and you uploaded your resume.

Execute shell:
Once we have uploaded the shell we know that its sitting on the server. The only thing we need to do now is to execute the shell from a browser so we get access to it. Example: So suppose i uploaded my shell as an attachment. If we want to executive it, we will use URL manipulation:
Sample:
http://www.something.com/attachment.php?attachmentid=451&d=1249607339 so that is the direct url to the attachment which is called execution. In the same way if you execute your shell, it will take you to a webpage where you will see everything thats on the server. And you will have FULL ACCESS to remove/edit/replace/delete the files!!

Defacing:
Defacing is a word which means"replacing the current index file with our own index page and messages. Different types of shells:
There are many shells available, most of them are public and some of them are private. Most of them does the same thing to give you the access of the server. "c99, r57, b0yzone, j32" aresome very common and easily available shells.