Authentication Testing - Testing for Bypassing Authentication Schema

Although for most applications, authentication leads to access -  there are certain cases were an intruder can just bypass the login page and directly access the "private" information.   This can be done through four different ways. Direct Page Request, Parameter Modification, Session ID Prediction, & SQL Injection.  Direct page requests occurs when the code checks for authentication only on the login page. Every other page in the administrator's does not check user credentials and thus can be accessed by just putting in the URL in the browser.  The second way to bypass authentication is through a modification of the URL parameter.  Some times, web apps uses fixed value parameters to signify a successful authentication.  So for example, we can easily change http://domain.com/admin/index.php?authentication=no  to authentication=yes. Then after resubmitting the data to the server, we should be in the admin panel.  The third way of bypassing authentication is through predicting an admin's session ID. Some web apps uses Session ID's as a means to manage authentication. The problem with this is that sometimes these session ID's just increases linearly which means it is easy to predict. We can get the correct session ID by using a bruteforce attack. Lastly, SQL Injection is another way of bypassing authentication. Due to the popularity of the topic, this will be covered in a future post.