As we all know, once we have connected to a Wi-Fi network and we have entered the password of said Wi-Fi network, our devices remember the password forever.
The next time you are within reach of the Wi-Fi network, your device automatically reconnects to the saved Wi-Fi network. In meantime, someone named Mr Darth has read the Wi-Fi password that has been advertised on a board in a public space. He now knows the Wi-Fi name and Password which your device has saved.
Mr Darth can now broadcast a cloned version of the saved Wi-Fi network, from his phone!
Once you leave the public area where you were connected to the public Wi-Fi he merely needs to follow you from a safe distance for your phone to connect to his. Your device is now in his hand.
