Below is a demonstration by Sandro Gauci of the Surf Jack attack being performed on Gmail. It also shows how Google’s Gmail can be prevented from being vulnerable to this attack by selecting the “always use https” option.
The “Surf Jack” security tool demonstrates a security flaw found in many public sites. The proof of concept tool allows testers to steal session cookies on HTTP and HTTPS sites that do not set the Cookie secure flag.
For a paper with detailed information go here.