In early August of 2008, almost exactly 15 years ago, the Defcon hacker conference in Las Vegas was hit with one of the worst scandals in its history. Just before a group of MIT students planned to give a talk at the conference about a method they’d found to get free rides on Boston’s subway system—known as the Massachusetts Bay Transit Authority—the MBTA sued them and obtained a restraining order to prevent them from speaking. The talk was canceled, but not before the hackers’ slides were widely distributed to conference attendees and published online.
In the summer of 2021, 15-year-olds Matty Harris and Zachary Bertocchi were riding the Boston subway when Harris told Bertocchi about a Wikipedia article he’d read that mentioned this moment in hacker history. The two teenagers, both students at Medford Vocational Technical High School in Boston, began musing about whether they could replicate the MIT hackers’ work, and maybe even get free subway rides.
They figured it had to be impossible. “We assumed that because that was more than a decade earlier, and it had got heavy publicity, that they would have fixed it,” Harris says.
Bertocchi skips to the end of the story: “They didn’t.”
Now, after two years of work, that pair of teens and two fellow hacker friends, Noah Gibson and Scott Campbell, have presented the results of their research at the Defcon hacker conference in Las Vegas. In fact, they not only replicated the MIT hackers’ 2008 tricks, but took them a step further. The 2008 team had hacked Boston’s Charle Ticket magstripe paper cards to copy them, change their value, and get free rides—but those cards went out of commission in 2021. So the four teens extended other research done by the 2008 hacker team to fully reverse engineer the CharlieCard, the RFID touchless smart cards the MBTA uses today. The hackers can now add any amount of money to one of these cards or invisibly designate it a discounted student card, a senior card, or even an MBTA employee card that gives unlimited free rides. “You name it, we can make it,” says Campbell.
To demonstrate their work, the teens have gone so far as create their own portable “vending machine”—a small desktop device with a touchscreen and an RFID card sensor—that can add any value they choose to a CharlieCard or change its settings, and they’ve built the same functionality into an Android app that can add credit with a tap. They demonstrate both tricks in the video below:
In contrast to the Defcon subway-hacking blowup of 2008—and in a sign of how far companies and government agencies have come in their relationship with the cybersecurity community—the four hackers say the MBTA didn’t threaten to sue them or try to block their Defcon talk. Instead, it invited them to the transit authority headquarters last year to deliver a presentation on the vulnerabilities they’d found. Then the MBTA politely asked that they obscure part of their technique to make it harder for other hackers to replicate.
The hackers say the MBTA hasn’t actually fixed the vulnerabilities they discovered and may instead be waiting for an entirely new subway card system that it plans to roll out in 2025. WIRED reached out to the MBTA ahead of the hackers’ presentation but hasn’t received a response.