Android OS Vendor Variants Transmit Data With No Opt-out

Updated Google Android devices transmit telemetry data while idle, even when users have opted out, according to study conducted earlier this year by Trinity College Dublin computer scientist Douglas Leith.

Handset vendors like Samsung that install proprietary versions of Android on their devices have the opportunity to offer better privacy. But they too gather data without giving users much choice in the matter, the study found.

In a paper PDF] published on Monday, Leith and Dr Paul Patras and Haoyu Liu, both with the University of Edinburgh, examined the data sent by pre-installed system apps in the Android variants installed on Samsung, Xiaomi, Huawei, Realme, LineageOS and /e/OS handsets in Europe.

These include the GApps package (Google Play Services, Google Play store, Google Maps, Youtube, etc.), and system apps that handset vendors install from the likes of Microsoft, LinkedIn, and Facebook.

The boffins from Trinity and Edinburgh universities found that, with the exception of /e/OS, "even when minimally configured and the handset is idle these vendor-customized Android variants transmit substantial amounts of information to the OS developer and also to third-parties."

And, they claim, there's no way to opt-out of this data collection.

Almost nowhere to run to

LineageOS is an open source Android distribution and /e/OS is a fork of LineageOS and Android by French entrepreneur Gaël Duval that's primarily notable for being "Google free."

The Android OS variants from Samsung, Xiaomi, Huawei, and Realme (Oppo) "all transmit a substantial volume of data to the OS developer (i.e. Samsung etc) and to third-party parties that have pre-installed system apps (including Google, Microsoft, Heytap, LinkedIn, Facebook)," the study says.

LineageOS, though distinct from Google's version of Android, sent a similar amount of data to Google, the researchers found, but they didn't observe data going to LineageOS developers or to pre-installed system apps aside from those operated by Google.

/e/OS, according to the boffins, sends no data to Google or third-parties and basically no information to /e/OS developers.

While Leith's research from April showed that Android and iOS devices were found transmitting data like IMEI number, hardware serial number, SIM serial number, phone number, device ids (UDID, Ad ID, RDID, etc), location, telemetry, cookies, local IP address, device Wi-Fi MAC address, handset Bluetooth UniqueChipID, the Secure Element ID (for Apple Pay), and the Wi-Fi MAC addresses of nearby devices, these vendor-customized versions of Android are even more chatty.

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The researchers note that Samsung, Xiaomi, Realme and Google all collect hardware device identifiers as well as identifiers that are resettable, ostensibly as a form of privacy protection.

"This means that when a user resets an identifier the new identifier value can be trivially re-linked back to the same device," they explain in their paper. "This largely undermines the use of user-resettable advertising identifiers."

Click to enlarge

They further note that multiple parties collect data from each handset, which makes it possible to cross-link the data each party has collected. For example, on the Samsung handset tested, the Google Advertising ID was sent to Samsung servers and several Samsung system apps rely on Google Analytics and Microsoft's OneDrive system app relies on Google's push service.

Similarly concerning is the way some of these vendors collect user interactions. For example, the Xiaomi handset's system app "com.miui.analytics" transmits the details of when app screens were viewed by the Xiaomi user, giving Xiaomi a picture of the timing of user phone calls. And this data gets sent outside of Europe to servers in Singapore.

Microsoft's Swiftkey keyboard on the Huawei handset does similar usage logging.

Missing the point

What's more, all of the handset makers, again with the exception of /e/OS, collect a list of all the apps installed on a handset, which isn't ideal if the app reflects sensitive or controversial interests.

"I think we have completely missed the massive and ongoing data collection by our phones, for which there is no opt out," said Leith in a statement. "We’ve been too focused on web cookies and on badly-behaved apps."

Leith said he hopes the research will help alert the public and lawmakers that action needs to be taken to give people control over the data leaving their phones.

We asked Samsung, Huawei, Xiaomi, Realme, and the e.Foundation for comment but we've not heard back. When The Register asked Google for comment about Leith's related study in April, a company spokesperson suggested phones are supposed to phone home with telemetry data, like modern cars do, to ensure everything is working properly.

This latest study by Leith, Patras, and Liu however argues what these vendor versions of Android are doing goes beyond telemetry that's necessary for phone maintenance.

"Although occasional data transmission to the OS developer to check for updates, etc. is to be expected, as we will see the observed data transmission by the Samsung, Xiaomi, Huawei, Realme and LineageOS Android variants goes well beyond this," the study says.

It also points to /e/OS as an example of privacy done right. "We find that /e/OS collects essentially no data and in that sense is by far the most private of the Android OS variants studied," the study says. ®

Updated to add

In an email to The Register, a spokesperson for LineageOS challenged the paper’s assumption that Google’s system apps come with LineageOS by default.

“The study linked chose to install a third party package (‘opengapps’) on a LineageOS device (per page 6),” the spokesperson said.

“Google Apps are not preinstalled on LineageOS. We have no control over what data is sent by third party applications a user chooses to install, including packages from Google. Those services are neither required nor recommended, and free open source alternatives (such as microG and F-Droid) exist.”