The other major problem with current Bluetooth devices is that some sensitive functionality is exposed to unauthenticated users. When designing a Bluetooth-enabled device, system designers may want to provide certain pieces of functionality to non-trusted users. Unfortunately, sometimes more functionality is exposed than is intended, and attackers can read and/or write information to which they shouldn’t have access. These types of vulnerabilities are device-specific; for instance, cell phones from one manufacture may be vulnerable while those from another are not.
Probably the best-known attack against this class of vulnerabilities is the BlueSnarf attack from Trifinite.org. Phones that are vulnerable to the BlueSnarf attack have exposed an interface designed for moving objects between two devices. (This interface is technically known as OBEX Push.) OBEX Push is commonly used for transferring contacts and vCards between devices. Unfortunately, some vendors ended up allowing OBEX Push requests to access data throughout the filesystem of the remote device, or at least allowing access to the entire contact database. Attackers can use OBEX Push against these vulnerable phones to read all available contacts, write new contacts, or even write arbitrary information to the remote phone.