Google started building a global database of Wi-Fi routers in 2007, using its Street View cars and Android phones to improve cell phone location tracking. The Guardian's Charles Arthur writes, "The results of its giant Street View exercise in which it took pictures of houses and shops but also gathered locations of Wi-Fi networks and - oops! - collected data from open Wi-Fi networks has all been collated."
By checking a phone against a global database of Wi-Fi networks, the device's location can be determined (within 100 feet) without the need to enable a phone's GPS features. It's not just Google, either; Skyhook wireless started "wardriving" back in 2003 to build a similar database of Wi-Fi networks, which Apple used until launching its own service last year.
Once a car or phone finds a Wi-Fi network, it sends the router's BSSID/MAC address, signal strength, GPS coordinates and more back to Google. Researcher Samy Kamkar's new android map tool lets you use run those router-specific MAC addresses through Google's database. Kamkar explains on his blog, the tool "allows you to ping that database and find exactly where any wi-fi router in the world is located" -- you can usually find your router's MAC address in the device's administration tools. If Google has tracked your router, plugging it into android map will reveal its longitude, country, county, street and even postal code number.
Kamkar told The Register, "They're sending all your GPS coordinates. They know how fast you're traveling. Theres a unique identifier that's always sent." By analyzing the phone's location and ID, Kamkar argued that Google would easily be able to map where you work and live. After it was revealed last week that Google and Apple are tracking phone users' location data, both companies are under pressure from consumers, congressmen and privacy groups looking for answers as to how, why and when this data is being tracked and transmitted.