How the Government Uses Advertising Data to Track People (and What You Can Do to Limit It)
It’s probably no surprise that government agencies have access to a lot of your data, partly because we give some of it directly to them, and partly because they can buy it from data brokers that already exist to harvest it, aggregate it, and sell it to other companies. A recent report from 404 Media confirms that Customs and Border Protection (CBP) is among those purchasing and using location data collected through ads to track users’ movements.
Immigration and Customs Enforcement (ICE), the FBI and a handful of other federal agencies have also purchased location data from brokers in recent years, but the internal Department of Homeland Security document obtained by 404 Media confirms that CBP obtained its location tracking in part from real-time bidding (RTB), which sits behind every online ad served to you.
The Electronic Frontier Foundation describes how this process exposes your location data, which happens in milliseconds every time you open an ad-supported app or visit a website. The app or website pings an ad tech company to determine which ads to serve, and that company sets up a “bid request” using your data, including your device’s advertising ID, IP address, demographic information, GPS coordinates, and more. This bidding request is sent to thousands of advertisers, and the highest bidder is the one that is finally displayed.
Meanwhile, ad tech companies and advertisers receive all your data, and organizations that buy that data can connect movements to specific devices, making it easier to monitor over a period of time.
How to protect your location data from tracking
As the EFF points out, law enforcement in almost every state can purchase location data from data brokers without first obtaining a warrant, so the onus is largely on users to protect themselves from location tracking. (It’s worth noting that Apple devices generally have more advanced privacy settings than Android, as apps running on iOS must request access to advertising identifiers, making it easier for users to opt out.)
All of this means that you can (and should) take some steps to minimize how your location is tracked and shared.
Disable advertising identifiers on your device
To remove advertising IDs on Android, go to Settings > Security & Privacy > Privacy Controls > Ads and press Remove advertising ID.
What do you think of it so far?
On iOS, disable Advertising ID globally under Settings > Privacy & Security > Tracking and deactivate Allow apps to request tracking. Then go to Settings > Privacy & Security > Apple Advertising and deactivate Personalized ads to eliminate internal tracking of Apple’s native services.
Check which apps have access to location services
You should know which apps use your location data and disable permissions where they are not essential to the app’s operation. You can also allow apps to access your location only when in use and turn off precise location sharing (so only your approximate location is visible).
On iOS, it’s under Settings > Privacy & Security > Location Serviceswhere you can select permissions and disable Precise location for individual applications. On Android, go to Settings > Privacy & Security > Privacy Controls > Permissions Manager.
Use airplane mode to stop real-time tracking
Airplane mode is an easy way to limit tracking, useful if you’re heading to a protest or other sensitive location. Your device can always store and transmit this data later, but EFF notes that most apps aren’t likely to do so.
