Secure RFID. Or Not.
Security issues frequently appear in the news regarding interception of Wireless
Local Area Network (WLAN) and Bluetooth device traffic, and each time they do, engineers
get busy trying to plug the newly revealed holes. As with the Windows™ operating
system, most of the effort tends to be reactive rather than proactive; resources
are just too scarce and expensive to act otherwise. Also as with Windows™ most of
the effort on the part of the miscreants tends to be directed toward the most popular,
and therefore the most likely to receive ample news coverage. Attacks on the MAC
OS or Linux just does not create enough of a media frenzy to make the work involved
Radio Frequency Identification Devices (RFID) are sort of in
that MAC OS and Linux category in the wireless data theft business. That is not
to say there is no reason for concern. Once confined to uses in commercial shipping
and maybe pet recovery implants, RFID is appearing in more and more every-day products.
Wal-Mart famously announced a plan to incorporate RFID product price scanning in
all their stores, both as a convenience to the shopper and as a means to more tightly
track inventory and, yes, customers. Car and truck keys have had embedded RFID chips
for many years now as a theft-prevention feature (Ford recently charged me $65 for
a single duplicate), as well as some forms of credit/debit cards, and specially-designed
access implements. Those last items, and other personal items like them, are what
you should begin worrying about.
A team of computer scientists Johns Hopkins
University in Baltimore and RSA Laboratories in Bedford, MA, has successfully deciphered
the codes of RFID-equipped keys that protect cars from theft and cards meant to
prevent fraudulent gasoline purchases. They demonstrated that "an attacker with
modest resources—just a few hundred dollars" of off-the-shelf equipment could pull
off the crime. The stubby wands that trigger the pumps at ExxonMobil gas stations
are particularly vulnerable according to a report at
Inside the head of an ignition key, the transponder must convince the vehicle's
computer that it has the correct 40-bit code before fuel will flow to the engine.
The transponders allow ExxonMobil customers to buy gas by waving the wand in front
of the pumps that use the Speedpass system.
While details of the code-breaking
technique and the results are not divulged, the information casts doubts on the
usefulness of the Texas Instruments (TI) RFID chip used in the anti-theft keys and
the gas pump wands. The researchers assert, "It's very important to ensure that
we get security right in wireless devices from the very start," and insist the theft
is preventable by using a larger number of bits. They suggest the de facto standard
of 128 bits. Surely such notoriety has gotten the attention of TI by now.
As can be seen in the pictures on the website, codes were ascertained merely
by trying every possible code until the correct one is found. Intercepting the code
is as simple as standing or sitting next to a person carrying the RFID implement
long enough to run through as many code tries as necessary. The next time you are
sitting in an airport with someone typing busily away on his laptop, he might just
be stealing your SUV key code or preparing for a few free trips to the gas station
on your account. Now, 2^40 is a pretty big number, and a lot of trials, but it does
not take all that long for a computer to crank through them. Besides, there's a
50-50 chance that the thief will only have to try 2^39 of them.