Firefox plugins

Firesheep – Firefox plugin
     
      Firesheep is a classic Penetration Testing tool used to audit web sessions. 
Firesheep is an extension for the Firefox web browser; however, some versions have been
unstable with recent Firefox releases. Firesheep acts as a packet sniffer that intercepts
unencrypted cookies from websites while they transmit over a network.

Web Developer – Firefox plugin
        Web Developer is an extension for Firefox that adds editing and debugging tools for web developers. 
Web Developer can be downloaded for free from the Firefox plugin store. 
One feature in Web Developer useful for session hijacking is the ability to edit cookies. 
This can be found as a drop-down option from the Firefox browser once Web Developer is installed.

Greasemonkey – Firefox plugin
Greasemonkey is a Firefox plugin that allows users to install scripts that make on the fly changes to web page content before or after the page is loaded. 
Greasemonkey can be used for customizing a web page appearance, web functions, debugging, combining data from other pages, as well as other purposes. 
Greasemonkey is required to make other tools, such as Cookie Injector, function properly.

Cookie Injector – Firefox plugin
Cookie Injector is a user script that simplifies the process of manipulating browser
cookies.
There are a lot of manual steps to import a cookie from a tool like Wireshark into a web browser.
Cookie Injector allows the user to copy paste a cookie portion of a dump, and have the cookies from the dump automatically created on the currently viewed web page.