A new investigation conducted by the Electronic Frontier Foundation has found that Android phones less than three years old could be broadcasting the Wi-Fi networks you’ve connected to. This is attributed to a feature called Preferred Network Offload introduced with Android’s Honeycomb operating system. The PNO sometimes blasts out the list of named networks your phone has connected to while searching for Wi-Fi connections and often during the time your phone is in sleep mode. What makes this particularly dangerous is it could show a person’s movement or activity based on the specificity of the Wi-Fi names.
The easy fix for the leak just requires you to head to the Advanced Wi-Fi settings and disabling the “Keep Wi-Fi on during sleep” option. This might also increase your battery power or data usage if you keep your data on.
Source: The Verge