Many Android Apps Expose Users to Attacks Due to Failure to Patch Google Library

A vulnerability in the Google Play Core Library continues to impact many applications several months after official patches were released.

The Google Play Core Library allows Android developers to deliver updates to their applications at runtime, via the Google API, without requiring interaction from the user.

The library can be used to download additional language resources, manage the manner in which feature modules and asset packs are delivered, trigger in-app updates, and more. Google Chrome, Facebook, Snapchat, and WhatsApp are only some of the apps that use this library.

Tracked as CVE-2020-8913 and addressed in March 2020, the vulnerability is a path traversal that could result in local code execution (LCE) “within the scope of any application that has the vulnerable version of the Google Play Core Library,” Check Point explains.

According to Oversecured, which provided technical details on this security bug in August, the flaw can allow an attacker to abuse the library to deliver executable modules to an application, essentially leading to arbitrary code execution within these modules.

“An attacker who had a malware app installed on the victim’s device could steal users’ login details, passwords, and financial details, and read their mail,” Oversecured notes.

In addition to the aforementioned path traversal, the attack relies on a combination of two features, one where all files that an application receives from Google Play are placed in a verified folder within the app’s sandbox, and another where other sources can push files into that sandbox.

Normally, the pushed files are placed into a ‘non-verified’ folder and not handled by the library, but said path traversal allowed an attacker to supply a path within their malicious application so that their nefarious file would be written to the ‘verified’ folder.

Thus, not only is the file automatically loaded and executed by the Google Play Core library, but it is no longer verified in the future, given the folder it is stored into.

The main concern regarding this flaw is that, although a patch was released months ago, many software developers have yet to implement it in their applications. An analysis performed by Check Point revealed that 13% of Google Play applications used the library, and that 8% of them had a vulnerable version.

Some of the apps found to be vulnerable included Viber, Booking, Cisco Teams, Moovit, Grindr, and OKCupid, all of which were patched after Check Point contacted the developers to inform them on the issue. However, apps such as Edge, PowerDirector, Xrecorder, and Yango Pro (Taximeter) remain vulnerable.

Related: Google Patches 30 Vulnerabilities With November 2020 Android Updates

Related: Android’s October 2020 Security Update Patches 48 Vulnerabilities

Related: Google Announces Android Partner Vulnerability Initiative

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Ionut Arghire is an international correspondent for SecurityWeek.

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