Cracks appear in Bluetooth security

[InfoSec News <isn () c4i org>]

http://www.computerworld.com/securitytopics/security/story/0,10801,90131,00.html

By John Blau
FEBRUARY 11, 2004

Be careful the next time you turn on your Bluetooth-enabled phone:  
You could unknowingly be opening the door to a nasty intruder who
could steal confidential information such as your address book or even
use your phone to make expensive calls.

Security experts in the U.K. have discovered serious flaws in some
Bluetooth-enabled phones, prompting one supplier of the vulnerable
phones, Nokia Corp., to recommend precautionary measures.

"We have developed a tool that allows us to connect to a number of
Bluetooth-enabled phones and download all sorts of confidential
information, such as address books, calendars and other attachments
without going through the normal pairing, or handshaking, process
between devices," said Adam Laurie, technical director and co-founder
of A.L. Digital Ltd. in London. "In fact, we have been able to obtain
this confidential data without giving users any indication whatsoever
that an intrusion is taking place."

A.L. Digital has discovered security flaws in four Nokia phone models:  
6310, 6310(i), 8910 and 8910(i).

Janne Ahlberg, manager of technology platforms at Nokia, confirmed on
Wednesday that these models are susceptible to potential attacks.  
Users of these phones in public places should either switch their
phone to the "nondiscoverable" or hidden mode, making them invisible
to others, or turn off the Bluetooth functionality completely, he
recommended. Users should also check that their Bluetooth "pairings,"  
or approved connections with trusted partners, are correct.

The U.K. security company detected similar flaws in phones
manufactured by Sony Ericsson Mobile Communications AB. The Sony
Ericsson models include the R520, T68i, T610 and Z1010.

Sony was unavailable for immediate comment.

Bluetooth technology allows users to swap data between mobile phones,
PDAs, notebook computers and a string of other devices within a few
meters of each other. It's becoming a standard feature of many
high-end devices.

Until now, the only known Bluetooth security shortcoming has been
"bluejacking," an increasingly popular means of exchanging short
three- or four-word messages in the display area designated for the
name of the initiating device, according to Laurie. The process,
essentially, allows communication to take place without pairing, which
requires partners to exchange a personal identification number (PIN)  
to establish a connection.

But Laurie said he and his colleagues at A.L. Digital have uncovered
not one but two new security flaws. He referred to the one as
"bluesnarf" and the other as a backdoor attack.

"Bluesnarf is a tool I've written that allows you to bypass the
pairing process to connect to a Bluetooth-enabled phone and,
essentially, break into the device to steal or manipulate data," he
said.

The backdoor attack, according to Laurie, involves establishing a
trust relationship through the pairing mechanism but later making the
pairing information invisible on the target's register of paired
devices to enable an anonymous connection. The process requires
participating users to first create a PIN and then enter this number
in each device in order to initiate a connection, he said.

The problem arises, Laurie said, when one of the "trusted" persons
decides to use the backdoor hacking method to hide the identification
data and gain unauthorized access to that person's device. "Unless you
happen to be staring at your phone and see a little icon appear
indicating a connection, you won't know that anyone has gained access
to your phone," he said.

Nokia said it isn't aware of any attacks against Bluetooth-enabled
phones and believes it's "highly unlikely" that these phones will
become broadly exposed to security attacks.

"From a security viewpoint, Bluetooth is actually very strong,"  
Ahlberg said. "There were just some implementation flaws that made
these security flaws possible in a couple of models."

Additional information about the security flaws detected by A.L.  
Digital is available online [1].

[1] http://www.bluestumbler.org/



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