Based on anonymized data collected from users of an app designed to check for a newly revealed vulnerability in many Android devices, Check Point discovered that one application in the Google Play store is exploiting the vulnerability to gain a high level of access to the Android OS, bypassing user permissions—and bypassing Google’s security scans of Play applications to do so. Update: A Google spokesperson told Ars that the offending app has been suspended in the Play store.

Further Reading Waiting for Android’s inevitable security Armageddon no easy way for Google or phone manufacturers alone to patch the problem.

At the Black Hat security conference in Las Vegas earlier this month, Check Point’s Ohad Bobrov and Avi Bashan presented research into an Android vulnerability introduced by software installed by phone manufacturers and cellular carriers that could affect millions of devices. Labeled by Bobrov and Bashan as “Certifi-Gate," the vulnerability is caused by insecure versions of remote administration tools installed by the manufacturers and carriers to provide remote customer service—including versions of TeamViewer, CommuniTake Remote Care, and MobileSupport by Rsupport. These carry certificates that give them complete access to the Android operating system and device hardware. The applications are commonly pre-installed on Samsung, LG, and HTC handsets.

Check Point has provided a free scanning application to allow individuals to determine if their Android device was vulnerable. Michael Shaulov, Check Point’s head of mobility product management, told Ars that there had been more than 100,000 downloads of the scanning app from Google Play, and more than 30,000 users had opted to provide anonymous scan results from their products. In a blog post published today, Check Point researchers share a summary of that data—a majority (about 58 percent) of the Android devices scanned were vulnerable, with 15.84 percent actually having a vulnerable version of the remote access plug-in installed. The brand with the highest percentage of devices already carrying the vulnerable plug-in was LG—over 72 percent of LG devices scanned in the anonymized pool had a vulnerable version of the plug-in.

Check Point

Check Point

Check Point

In a small fraction of devices scanned, Check Point researchers found an app that was actively exploiting the vulnerability. A tool called “Recordable Activator” from UK-based Invisibility Ltd was advertised as an “EASY screen recorder” that doesn’t require root access to the device. But in fact once installed from the Google Play store, the app downloaded a vulnerable version of the TeamViewer plug-in from another source, Shaulov told Ars. “Because the plug-in is signed by various device manufacturers,” Check Point researchers wrote in their blog post, “it’s considered trusted by Android, and is granted system-level permissions. From this point ‘Recordable Activator’ exploits the authentication vulnerability and connects with the plug-in to record the device screen.”

While it’s possible for device owners to uninstall vulnerable plug-ins, the vulnerability that allows the plug-in to be installed in the first place without the user’s knowledge can’t be fixed so easily—because the permissions for remote access are burned into the ROM of the device itself. And in some cases, as Bobrov said at Black Hat, the tool is pre-installed and unreachable by the customer. “To get rid of it, you need an upgrade of Android OS,” he explained.

In some scenarios—not with TeamViewer, but another of the vulnerable tools— Bobrov said, “you can trick this tool with SMS to respond and get it to work with a malicious command and control server. The user doesn’t see any of this.” While most of the third-party developers have issued patches to their tools to the Play store, he added, “the issue is more problematic—it’s not just the bug itself, it's the architecture. The vendors themselves signed this tool with their certificate, and there is no way to patch this problem currently. If someone a year from now can trick you into installing a vulnerable version, they’ll still be able to take control.”

Based on Check Point’s findings, that’s exactly what Invisibility Ltd is doing for what is advertised as a legitimate application. Given how easily the developer was able to bypass Google Play’s security scans, it’s possible there are already more malicious applications already out there.