Kaitlyn Tiffany, Vox:
So what do these third-party advertisers do that’s so bad? A study conducted last year by security researchers at UC Berkeley gives us some insight.
The study focused on children’s privacy and resettable advertising IDs —the string of numbers and letters that identify you and keep a log of your clicks, searches, purchases, and sometimes geographic location as you move through various apps — in contrast with non-resettable, persistent identifiers. Phone security experts recommend regularly resetting it to limit advertisers’ ability to track you. (You can do that in the Advertising section at the bottom of the Privacy settings on an iPhone, or in the Ads menu in the Services section of an Android device’s settings.)
The study found something alarming: Of 3,454 children’s apps that share resettable advertising IDs, 66 percent were sharing persistent identifiers as well. You could reset the advertising ID every 20 minutes on the device your child is using, if you wanted to, but it wouldn’t do anything to clear their history. The only way to reset that device ID is by factory-resetting the phone or tablet and starting from scratch. More importantly, the study found that 19 percent of children’s apps contained ad-targeting software with terms of service so predatory that they’re not even legal to include in apps designed for children. Kids under 13 aren’t supposed to be tracked between apps at all, especially for advertising purposes, and especially as part of a permanent history of their digital lives.
This is the kind of thing that I would like to see sifted out of apps before they make it into the App Store. There are honest justifications for developers to use an analytics framework to sort out bugs within their apps or figure out how often a feature is being used. Still, I would like to see more limitations placed on the monetization of data collected from app usage, and on persistent identifiers — particularly when they’re operated by a third party and can therefore be used to track users across multiple apps and even across devices.
By the way, do yourself a favour and opt out of ad targeting on your iOS devices.