Security researchers from MetaIntell have discovered security vulnerability in the new version of Facebook SDK that put millions of Facebook user's Authentication Tokens at risk.
With help of Facebook SDK for Android and iOS it is easy to integrate mobile apps with Facebook platform. The set of program tools gives creators a chance to simplify process of reading and writing to Facebook APIs and other.
“Login as Facebook” function is a secure and personalized way for users to sign, because sharing passwords is not needed. When the user approves the permissions to transfer data that the application requested, the Facebook SDK implements the OAuth 2.0 User-Agent flow to retrieve the secret user’s access token required by the apps to call Facebook APIs to modify user's Facebook information on their behalf.
Tokens are stored in unencrypted view in SDK Facebook library though sharing of them is forbidden. It turns out that even if the Android or iOS are non-rooted, it is possible to get access to the device’s file system.
Ability to use any application which has the right to access device file system is dangerous and it is able to steal users’ Facebook access tokens remotely. It gives attacker possibility to access victim’s Facebook account information.
Video demonstrates stealing token which was used with help of popular messaging application “VIBER” for iOS.