Hello guys,      I’m back with a new post and a new discovery. As I’m a Mobilis GSM  subscriber I thought about registering to their online invoice system, I  took the steps and I have been provided with access to my account  online .      EXPLORING THE WONDERLAND :      When you first login you get this page :                 You can do some things from here, like viewing/downloading your  invoices and canceling the online account, we are mainly interested in  the invoices as they contain all information about the target in order  to help conduct further attacks on him/her                I hooked up burp suite proxy to the browser and I logged in, I was amazed about what I was seeing  …. this is happening upon login :                                            Isn’t that a session initializer ? : /servlet/InitSessionExt?USER=”account_id”&ACCESS=1&INVOICE=”invoice_id”        The “account_id” can be brute forced as it a sequence number, but how  can we get the “invoice_id” f...