Security researchers have uncovered a serious flaw in the authentication and data transfer mechanisms in some Bluetooth-enabled mobile phones.
Data including a user's entire phonebook and calendar could be nicked from a range of Nokia and Ericsson phones using what researchers Adam and Ben Laurie of A.L. Digital describe as a "SNARF" attack.
They have written a paper warning how confidential data could be stolen from some Bluetooth enabled mobile phones.
"It is possible, on some makes of device, to connect to the device without alerting the owner of the target device of the request, and gain access to restricted portions of the stored data therein, including the entire phonebook," the paper states. "This is normally only possible if the device is in 'discoverable' or 'visible' mode, but there are tools available on the Internet that allows even this safety net to be bypassed."
Ericsson T68s, T68is and T610s, along with Nokia 6310is and 7650s are vulnerable to the exploit whilst in 'visible' mode, according to A.L. Digital's preliminary research.
Look out for that backdoor!
Nokia 3610is are vulnerable to a second, even more invasive attack. The memory on this phone (and some other models) can be accessed by a previously trusted ("paired") device that has since been removed from the trusted list. By exploiting this vulnerability an attacker is able to copy all the information on a targeted device, including media files such as pictures and text messages. This backdoor attack could also permit phreakers to access Internet or GRPS services without a user's knowledge or consent, A.L. Digital warns.
The media spotlight has recently fallen on bluejacking: the technique of anonymously sending messages to users of other Bluetooth-enabled devices who have switched on the technology and made their handset 'visible' to other users in the immediate vicinity.
Bluejacking creates a means to send unexpected, unsolicited messages to users even in areas where there is no network coverage. This can all be innocent fun but A.L. Digital warns that bluejacking may also be used by attackers as a means to trick users into pairing with an attacker, exposing users to further (more serious) attacks.
Wake up call
In the interests of full disclosure, A.L. Digital has published a paper on the security shortcomings of bluetooth without waiting for manufacturers to develop security fixes. A.L. Digital said it did this because it believes that it is more important to "alert the general public to the fact that the problem exists, and to give them the information required to adequately defend themselves".
A.L. Digital advises users to set their device to "invisible" or can simply shut off Bluetooth when not using it. "To permanently remove a pairing, and protect against future backdoor attacks, it seems you must perform a factory reset, but this will, of course, erase all your personal data," it adds.
In order to validate its research, A.L. Digital has developed a number of proof of concept tools which it is prepared to share with manufacturers - but not with the Internet community at large. ®
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