Do you want to download the InstaSheep hijack tool? Then you will need to read this article about the Instasheep tool which allows hackers to hijack Instagram profiles.
The Instagram application uses HTTP to communicate with the servers of Instagram.
The communication includes user account names, and an identifying account number.
The credentials, like the password are communicated via a secure line, but when information is passed back.
The information is stored in a Cookie, that can be used on the same network without reauthentication.