Brian Krebs:

Delaware-based Atlas Data Privacy Corp. helps its users remove their personal information from the clutches of consumer data brokers, and from people-search services online. Backed by millions of dollars in litigation financing, Atlas so far this year has sued 151 consumer data brokers on behalf of a class that includes more than 20,000 New Jersey law enforcement officers who are signed up for Atlas services.

…

How are advertisers and data brokers gaining access to so much information? Some sources of MAID data can be apps on your phone such as AccuWeather, GasBuddy, Grindr, and MyFitnessPal that collect your MAID and location and sell that to brokers.

…

Based on the data sets Atlas acquired — many of which included older MAID records — they estimate they could locate roughly 80 percent of Android-based devices, and about 25 percent of Apple phones. Google refers to its MAID as the “Android Advertising ID,” (AAID) while Apple calls it the “Identifier for Advertisers” (IDFA).

That’s a huge gap between iOS and Android. A few years ago, Apple started requiring apps to show an “Allow” or “Ask App Not to Track” dialog box if they wanted to collect a device’s IDFA. On Android, you still have to dig through settings to disable ad ID tracking.

Krebs suggests helping friends and family disable ad ID tracking, and not just for altruistic reasons:

Because while your device may not be directly trackable via advertising data, making sure they’re opted out of said tracking also can reduce the likelihood that you are trackable simply by being physically close to those who are.