How the Government Uses Ad Data to Track People (and What You Can Do to Limit It)
It’s probably no surprise that government agencies have access to a significant portion of your data—partly because we share some of it directly with them, and partly because they can purchase it from existing data brokers to collect, aggregate, and sell to other companies . A recent report from 404 Media confirms that U.S. Customs and Border Protection (CBP) is among those purchasing and using location data collected through advertising to track users’ movements.
Immigration and Customs Enforcement (ICE), the FBI, and several other federal agencies have also purchased location data from brokers in recent years, but an internal Department of Homeland Security document obtained by 404 Media confirms that CBP partially obtains location data from the real-time bidding (RTB) system that underlies every online ad you see.
The Electronic Frontier Foundation describes how this process exposes your location data, which happens within milliseconds every time you open an app with an ad or visit a website. The app or website sends a request to an ad tech company to determine which ads to show, and that company creates a “bid request” using your data, including your device’s advertising identifier, IP address, demographic information, GPS coordinates, and more. This bid request is sent to thousands of advertisers, and the highest bidder’s ad is ultimately displayed.
Meanwhile, both ad tech companies and advertisers receive all of your data, and the organizations that purchase that data can link your movements to specific devices, allowing for monitoring over a period of time.
How to protect your location data from tracking
As the EFF notes, law enforcement agencies in nearly every state can purchase location data from data brokers without a warrant, so the primary responsibility for protecting themselves from location tracking lies with users. (It’s worth noting that Apple devices typically have more privacy-focused settings than Android devices, as iOS apps are required to request access to advertising identifiers, making it easier for users to opt out of tracking.)
All of this means there are several steps you can (and should) take to minimize tracking and sharing of your location information .
Disable advertising identifiers on your device.
To remove advertising identifiers on Android, go to Settings > Security & Privacy > Privacy Management > Advertising and tap Remove Advertising Identifier .
On iOS, disable the advertising identifier globally in Settings > Privacy & Security > Tracking and uncheck “Allow apps to ask to track.” Then, go to Settings > Privacy & Security > Apple Advertising and disable Personalized Ads to prevent internal tracking for Apple’s own services.
Audit which apps have access to location services.
You should be aware of which apps use your location data and disable permissions for those that aren’t necessary for their operation. Alternatively, allow apps to access your location only while you’re using it and disable precise location sharing (so that only your approximate location is displayed).
On iOS, this is located in Settings > Privacy & Security > Location Services , where you can select permissions and disable precise location services for individual apps. On Android, go to Settings > Privacy & Security > Manage Privacy > Permission Manager .
Turn on Airplane Mode to stop real-time tracking.
Airplane mode is a way to limit tracking with the press of a button, which is useful if you’re heading to a protest or other sensitive location. Your device can still store and share this data later, but the EFF notes that most apps are unlikely to do so .