Possible security vulnerability in Dropbox?

A possible security hole in Dropbox ? "Newton’s concept, tested on a Windows machine, uses Dropbox’s own configuration files; configuration data, file/directory listings, hashes which are stored in numerous SQLite database files located in %APPDATA%\Dropbox. Inside one file lies a database row containing a users “host_id”, which is used to authenticate each individual user. Modifying this file and changing the host_id to that of another Dropbox user automatically authenticates the account, providing complete access to that person Dropbox until the user realises that there is a new computer in the “Linked Devices” section of the Dropbox website." Dropbox says there is no issue, a successful attack requires access to the user's computer (which seems inconsistent with the above), and that this is similar to stealing someone's cookies and using them to access Web services. I would think for a service as potentially sensitive as Dropbox, something more secure than cookies could be used, and they could become invalid when used from a different machine.