Android NFC hack enables travelers to ride US subways for free, researchers say

The researchers who developed the application said transit systems in other US cities could be vulnerable

Contactless fare cards in the New Jersey and San Francisco transit systems can be manipulated using an Android application, enabling travelers to reset their card balance and travel for free, researchers demonstrated on Thursday during the EUSecWest security conference in Amsterdam.

An NFC (near field communication) Android smartphone can read the data from a fare card with, for instance 10 rides on it, using the "UltraReset" application, said Corey Benninger and Max Sobell, security researchers at the Intrepidus Group and the application's developers. When travelers have used up their balance they are able to write the stored data back to the card using the same app, resetting the balance to 10 rides, the researchers said.

"I can do that over and over again if I chose to," Benninger said during his talk. UltraReset works on Android 2.3.3 or later. (See a video of the researchers demonstrating the NFC hack in this Vimeo clip.)

The application takes advantage of a flaw found in particular NFC-based cards, the researchers said, adding that these cards are used in the San Francisco Muni and the New Jersey Path transit systems.

Both systems were tested by the researchers and both cities were informed about the possible abuse of the system, they said. "Both systems are still vulnerable as far as we know," said Benninger, who added that San Francisco was informed in December 2011.

The hack exploits the Mifare Ultralight chip used in disposable contactless NFC cards, the researchers said. This type of chip allows anyone who has the know-how to rewrite data to the NFC chip, they said. "I coded the app in one night," Benninger said, "and I'm not a coder so if somebody knows what they are doing it is pretty easy to do."

The Mifare Ultralight can work much like a standard punch card system, but instead of punching holes in a paper ticket the card can flip bits on to indicate that a travel unit has been used, the researchers said. Those bits can never be turned back, but in the vulnerable systems user information on the card is checked but the bits are never turned on, which enables exploiters to rewrite the cards, they added.

Other U.S. cities including Boston, Seattle, Salt Lake City, Chicago and Philadelphia also use a contactless ticketing system and those systems could also be vulnerable for the same technique, they said. Those systems, however, were not tested by the researchers, who said they had not been able to travel everywhere.

An adjusted version of the UltraReset app, dubbed UltraCardTester, was made available for download by the researchers on Thursday to enable people to test their local transit system's security. UltraCardTester has the same abilities as UltraReset but isn't able rewrite the card. The function was taken out so people don't abuse it, Benninger said.

The app is, however, able to see if the bits are turned on or not, he added, saying that this gives a good indication whether the system is vulnerable. "But you won't be able to check the back end," Benninger said.

The vulnerability could be fixed relatively easy, according to the researchers. Transit companies could use a more secure chip, or adjust their back-end systems to make sure the bits in the cards are turned on when travel units are used, they said.

"Our purpose is not to rub anybody's nose in," said Sobell. "We just want to raise awareness for an issue that potentially could affect many systems."

Loek covers all things tech for the IDG News Service. Follow him on Twitter at @loekessers or email tips and comments to loek_essers@idg.com

Join the newsletter!

Or

Sign up to gain exclusive access to email subscriptions, event invitations, competitions, giveaways, and much more.

Membership is free, and your security and privacy remain protected. View our privacy policy before signing up.

Error: Please check your email address.
Keep up with the latest tech news, reviews and previews by subscribing to the Good Gear Guide newsletter.

Loek Essers

IDG News Service
Show Comments

Most Popular Reviews

Latest Articles

Resources

PCW Evaluation Team

Tom Pope

Dynabook Portégé X30L-G

Ultimately this laptop has achieved everything I would hope for in a laptop for work, while fitting that into a form factor and weight that is remarkable.

Tom Sellers

MSI P65

This smart laptop was enjoyable to use and great to work on – creating content was super simple.

Lolita Wang

MSI GT76

It really doesn’t get more “gaming laptop” than this.

Jack Jeffries

MSI GS75

As the Maserati or BMW of laptops, it would fit perfectly in the hands of a professional needing firepower under the hood, sophistication and class on the surface, and gaming prowess (sports mode if you will) in between.

Taylor Carr

MSI PS63

The MSI PS63 is an amazing laptop and I would definitely consider buying one in the future.

Christopher Low

Brother RJ-4230B

This small mobile printer is exactly what I need for invoicing and other jobs such as sending fellow tradesman details or step-by-step instructions that I can easily print off from my phone or the Web.

Featured Content

Don’t have an account? Sign up here

Don't have an account? Sign up now

Forgot password?