‘Anonymous’ Mobile Advertising IDs Aren’t So Anonymous

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A new investigation from Motherboard shows that the anonymous marketing IDs assigned to smartphone users are not nearly as anonymous as they seem.

Most mobile operating systems are basically built to help serve you ads: whether you’re using Android or iOS, phone companies have historically assigned specific identifiers to devices, called (MAIDs), or mobile advertising IDs, that are supposed to help app developers better customize the commercials they shove in your face. (Apple’s situation has changed recently, more on that below.) In essence, they are meant to track a “customer journey and ‘remember’ his or her choices,” as one company so delightfully puts it, though the identity of the phone’s user is ostensibly supposed to remain invisible to advertisers.

However, as you might have guessed, those IDs don’t really stay anonymous. In fact, there’s an entire niche within the data brokerage industry devoted to “unmasking” the specific users of MAIDs and selling that information to advertisers.

To garner proof of this, Motherboard reporters went undercover as potential customers to a data broker, whose CEO willingly told them that they have “one of the largest repositories of current, fresh MAIDS<>PII in the USA.” The outlet reports that the firm links the MAIDs to “full name, physical address, and their phone, email address, and IP address if available,” not leaving much to the imagination.

Many of these companies refer to their services as “identity resolution,” with one company, called FullContact, offering a product called a “whole-person Identity Graph,” which includes “both personal and professional attributes of an individual, as well as online and offline identifiers,” Motherboard reports.

Aside from ravaging the privacy of just your casual phone user, this industry practice of MAID “unmasking” could prove especially dangerous for those in sensitive vocations, some experts have warned.

“Anyone and everyone who has a phone and has installed an app that has ads, currently, is at risk of being de-anonymized via unscrupulous companies,” Zach Edwards, a researcher in the area, told Motherboard. “There are significant risks for members of law enforcement, elected officials, members of the military and other high-risk individuals from foreign surveillance when data brokers are able to ingest data from the advertising bidstream.”

The sad truth is that a majority of readers are probably not at all surprised by this information. Most Americans are so used to being lied to and spied on by companies that the notion that your supposed anonymous ID isn’t anonymous is obvious, a no-brainer.

Still, if you want to opt out of having a MAID at all, there are options. For Android users, you can opt out of this whole creepy situation, just go to Settings > Google > Ads, at which point you’ll be shown your specific advertising ID and asked if you want to opt out of ad personalization. In the case of iOS, the recent 14.5 update that dropped in April came with new privacy controls, including an important feature that forces apps to ask permission to track you, essentially making this kind of surveillance opt-in for iOS users. You can still explicitly opt-out of using the identifier, however.

In both cases, you can also reset your advertising ID, which ostensibly helps give you a new consumer identity—though, why even have one at all, if you can help it?