The revelations about just how embedded into every facet of modern, technological life the NSA is just keep coming. The spy agency isn’t just collecting calling records and tracking electronics; they’re in your iPhone games, too.

A joint report by the New York Times and ProPublica in the US and the Guardian in the UK reveals that the NSA and its British counterpart have been quietly collecting massive amounts of data on mobile users from apps like Angry Birds.

It’s not the first time the NSA has used video games as a way to dig up data, but this works slightly differently than eavesdropping on Xbox Live conversations. The agency is assembling enormous volumes of data from the apps people run on their smartphones.

A privacy-savvy mobile user is likely to be cautious choosing, installing, and running apps that might collect certain data, but that may not actually help. The data in question comes from something like a secondary layer of use.

When you install an app on your mobile phone, you give that program a certain set of permissions. Maybe it’s allowed to access your contacts, or to prevent your phone from entering sleep mode, or to use your phone’s GPS to determine your location and present custom content based on that. You can see that list before you install or run an app (depending on your phone type), and choose to back out rather than to proceed.

Some of the data the NSA and its counterpart organization in the UK have gathered comes from “leaky” apps that users have authorized in that manner. But much of the information is one more step removed. Advertising companies create user profiles based on data they scrape from users’ apps, and those profiles are subject to retrieval by the spy agencies.

ProPublica notes that the available data varies by which ad company is collecting it. Burstly and Google, two of the biggest ad companies, have profiles that “contain a string of characters that identifies the phone, along with basic data on the user like age, sex and location.” Profiles can also contain other data, including current phone use–that is, if the user is making a call or playing music–and the user’s annual household income.

And that’s not all of it. Depending what apps you use, and what advertising company has arrangements to work with the developer, plenty more personal information can be out there:

Another ad company creates far more intrusive profiles that the agencies can retrieve, the report said. The names of the apps that generate those profiles were not given, but the company was identified as Millennial Media, which has its headquarters in Baltimore.

In securities filings, Millennial documented how it began working with Rovio in 2011 to embed ad services in Angry Birds apps running on iPhones, Android phones and other devices.

According to the report, the profiles created by Millennial contain much of the same information as others, but several categories that are listed as “optional,” including ethnicity, marital status and sexual orientation, suggest that much wider sweeps of personal data may take place.

Nobody’s quite sure how Millennial finds or creates its data–whether the users voluntarily share their information, or whether the categories are created by inference and extrapolation. Nor do any of the documents the NYT and ProPublica accessed indicate why such information would be valuable to national security interests.

Between data pulled from smartphones and data pulled from traditional computer-based web use, the NSA is all but drowning in an enormous volume of information about ordinary folks’ information-seeking habits.

Is any of the massive-scale spying and information-gathering useful? The answer is a resounding, “Kind of, maybe, sort of.” ProPublica reports that the NSA claims that several successful investigations–an Al Qaeda bomb plot in 2007, a drug cartel hit squad in 2010–have been made by mining smartphone data. But those investigations began “with something closer to a traditional investigative tip or lead.”

In other words, the data captured from smartphone use can indeed be massively useful to law enforcement or anti-terrorist authorities if used as part of an existing investigation. But nobody inside the NSA quite seems to know what to do with the mountain of private citizens’ data they now hold.

Spy Agencies Probe Angry Birds and Other Apps for Personal Data [ProPublica]

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