What is the way that an action can be tracked by an application that does not allow location information access on a smartphone?

ByPixel Fantasy

When installing the Android application, you will be asked permission of necessary functions beforehand, so caution is required for applications that require unnecessary functions. In order not to trace the location information unnecessarily, it is safe to not allow location information except for reliable apps, but even a simple game application that only requests access to the Wi - Fi status, smartphone There is a way to be able to trace the position information of.

Tracking Human Mobility using WiFi signals
(PDF file)http://arxiv.org/pdf/1505.06311v1.pdf

How apps track your location without asking for permission - Trustlook News
http://blog.trustlook.com/2015/06/02/how-apps-tracking-your-location-without-asking-for-permission/

I discovered a way to track user's location information from an application that does not allow access to location informationDenmark Institute of TechnologyThe research team has found that you can track location information from the app just by accessing the Wi - Fi status. In Android, the Wi-Fi status is regarded as a function with low privacy risk compared with the function such as location tracking etc. When access to the Wi-Fi status is permitted, the terminal will scan "SSID list", "BSSID list Scan "," Signal condition of scanned list "," IP address to connect to access point ", and so on.

BSSIDIs the MAC address of the wireless access point and seems to be able to specify the position information with this BSSID and radio field intensity data. Specifically, when an application acquires a list of BSSIDs, it is possible to determine the location of the user in a rather narrow range from the list of nearby wireless access points. This is because radio waves from most wireless access points do not reach 100 meters from the transmission source and by acquiring real time radio wave intensity data together, it becomes possible to estimate how the user is moving I will. In addition, this method can track location information even if the terminal's GPS and Wi-Fi functions are turned off.

In order to trace location information in this way, installation location data of a large number of access points are required, but for example, geographical database of wireless access points around the world "WiGLE"It seems that it is not too difficult to clear up this problem since the location of nearly 200 million wireless access points is recorded all over the world.


The following is actually a 48-hour action tracking the position of the author's author from the access point, and how the target is traveling through the city is indicated by a line on the map. The four blue circles surround the two offices and supermarkets at home, you can see that the day's actions and private life are all clear. In the graph below, the time passed through the access point is recorded, and only 8 access points are used for tracking this position information.


The Danish Institute of Technology, which discovered the location information tracking method using Wi-Fi, is a Wi-Fi tracking application "WiFi WatchdogWe have completed the application, Google Play is on the way. If you actually install it, you can experience how you can track location information with just the Wi-Fi status.

WiFi Watchdog - Android application on Google Play
https://play.google.com/store/apps/details?id=dk.dtu.compute.mywifiscanner


In addition, anti-virus application for Android "Trustlook SecurityTrustlook also offers this issue on blogs, and warns that this technique is applicable to iOS applications even though it is not written in the paper.