Twitter fixed a bug that allows a third-party app to read the user message without user consent. The bug resides in the apps that uses PIN to complete the authorization instead of OAuth token-based procedure.

Terence Eden discovered the Twitter bug and submitted to Twitter through HackerOne platform. He was awarded $2,940 for reporting the bug.

Twitter bug Allows Unauthorized Access

Eden says the Twitter API keys are available freely, which allows an unapproved Twitter app can still use the Twitter API.

Twitter has enforced some security restriction for the apps, the important one is the callback URLs which limits the apps access only to the predefined URLs.

But not every app has the URL or supports callbacks, instead some app use secondary authorization which lets users log in by typing a PIN into your app and the PIN app don’t display the correct OAuth information to the user.

For some reason, Twitter’s OAuth screen says that these apps do not have access to Direct Messages. But they do! In short, users could be tricked into allowing access to their DMs, reads Eden’s blog post.

The bug has been reported to Twitter by Eden on 2018-11-06 and Twitter fixed the issue by 2018-12-06. Here you can find the proof-of-concept python code.

Twitter reported that we do not believe anyone was mislead by the permissions that these applications had or that their data was unintentionally accessed by the Twitter for iPhone or Twitter for Google TV applications as those applications use other authentication flows. To our knowledge, there was not a breach of anyone’s information due to this issue. There are no actions people need to take at this time.

Recently Facebook fixed and revealed a new photo API bug that may have been affected by nearly 68 million users and 1,500 apps built by 876 developers.