A critical security flaw in Microsoft’s OneDrive File Picker has exposed millions of users to unauthorized data access, allowing third-party web applications to gain complete access to users’ entire OneDrive storage rather than just selected files.
The vulnerability arises from the picker’s implementation of insufficient OAuth scope granularity, which requests broad File Access.Read.All or Files.ReadWrite.All permissions even when users intend to upload or share a single file.
Unlike competitors such as
Google Drive, which offers fine-grained OAuth scopes like drive.file to restrict access to app-created or user-selected files, Microsoft’s implementation grants unrestricted access to all OneDrive content.
Dropbox employs an even more secure approach with its Chooser SDK, using a proprietary endpoint that avoids OAuth flows entirely.
A critical security flaw in Microsoft's OneDrive File Picker has exposed millions of users to unauthorized data access, allowing third-party web applications to gain complete access to users' entire OneDrive storage rather than just selected files.
cybersecuritynews.com
