Smartphone operating systems have ramped up their privacy settings in recent years to let users pick and choose what information apps can get, but it seems those permissions aren’t ironclad. A new study revealed that over 1,300 Android apps can scrape certain personal data anyway, even if a user explicitly denied access to it.

Researchers at the International Computer Science Institute (ICSI) created a controlled environment to test 88,000 apps downloaded from the US Google Play Store. They peeked at what data the apps were sending back, compared it to what users were permitting and - surprise - 1,325 apps were forking over specific user data they shouldn’t have.

Among the test pool were “popular apps from all categories,” according to ICSI’s report.

The researchers disclosed their findings to both the FTC and Google (receiving a bug bounty for their efforts), though the latter stated a fix would only be coming in the full release of Android Q, according to CNET.

What are the loopholes for Android users?

Before you get annoyed at yet another unforeseen loophole, those 1,325 apps didn’t exploit a lone security vulnerability - they used a variety of angles to circumvent permissions and get access to user data, including geolocation, emails, phone numbers, and device-identifying IMEI numbers.

One way apps determined user locations was to get the MAC addresses of connected WiFi base stations from the ARP cache, while another used picture metadata to discover specific location info even if a user didn’t grant the app location permissions. The latter is what the ICSI researchers described as a “side channel” - using a circuitous method to get data.

They also noticed apps using “covert channels” to snag info: third-party code libraries developed by a pair of Chinese companies secretly used the SD card as a storage point for the user’s IMEI number. If a user allowed a single app using either of those libraries access to the IMEI, it was automatically shared with other apps.

Most insidiously, the ICSI researchers found that a certain number of apps were certifiably using these loopholes...but thousands more had the potential to do so. For example, they found 42 apps that accessed a user’s location via MAC address using ioctl system calls - but 12,408 apps had the specific code that would allow them to do the same.

By their own admission in the report, their test system might not have triggered this behavior - or the app had the required permission anyway and the data transmitted wasn’t seen as suspicious.

But in any case, it will be up to the FTC and Google whether these apps violate the ‘notice and consent’ doctrine required of apps in the US - that they notify users that they’d like to harvest data and require consent before doing so. “ In practical terms, though, these app behaviors may directly lead to privacy violations because they are likely to defy consumers’ expectations,” the ICSI report concludes.

Of course, the report’s scope only includes 88,000 apps - more could be violating permissions without user notice. But crucially, the test pool only contained apps downloaded off the US Google Play Store; it’s unclear if Android apps in other regions are exploiting similar loopholes to scrape user data despite permissions.