How to hack 6G: Make a metasurface

You might know of a man-in-the-middle attack, where an eavesdropper intrudes on a transaction or communication and intercepts the victim’s transmitted data. A team from Brown University and Rice University has advanced the concept by throwing a metamaterial and a drone into the mix.

In findings presented at the San Antonio-based conference ACM WiSec 2022 in May, after placing a lab-made, wave-manipulating metasurface in-between a transmitter and receiver, the researchers steered a 150-GHz beam to the eavesdropper, exposing vulnerabilities in 6G communications, which will likely rely on such high frequencies.

While some telecom pros aren’t expecting 6G applications to arrive until 2030, and companies are only beginning to “propose technological requirements for the sixth-generation wireless communication,” the university research reminds implementers to be proactive on security before mainstream adoption.

The hack. The basic supplies needed for the hack could be picked up on one trip to Staples: some paper, a printer, a foil transfer sheet, and a laminator. To create a metasurface, the team hot-stamped a metal-foil pattern onto the paper. The design: rows of, C-shaped, split rings, each with various openings and orientations.

“Those openings and orientations are very specifically done to get the signal to diffract in the exact direction Eve wants,” said Zhambyl Shaikhanov, a Rice grad student on the project, in May 2022. And what “Eve,” or the eavesdropper, “wants” in the exercise is to hear the conversation and decode the data as well as the intended receiver can—without the intended receiver noticing.

“It’s a very low-profile attack,” Brown professor Daniel Mittleman, a co-advisor in the experiment, told IT Brew. “If it’s designed correctly, it’s hard for the intended receiver to detect that anything’s going on.”

The team even used a drone to show how an aircraft-in-the-middle attack could work if it held the 3-by-3-inch metasurface. (Watch a demonstration here.)

Getting ready for 6G. While no 6G standards or commercial applications exist currently, preparations are underway for its arrival.

Organizations like the Next G Alliance—a North American industry body featuring members like Apple, Google, and AT&T—have formed, forecasting a number of 6G applications, from immersive communication to service robots. Such ideas require the high bandwidth and low latency provided by a 6G network operating in the higher frequencies of the radio spectrum.

Attacks are difficult at higher frequencies, according to Mittleman, but they aren’t as “impossible” as previously thought, and the metasurface hack demonstrates that safeguards must be considered in the preparation stages.

“How you think about security, how you develop ways to combat malicious actors, is going to be different,” said Mittleman. “But it is not a topic that you can ignore, just because you’re at high frequencies and the beams are narrower.”

Discovering 6G vulnerabilities provides an opportunity to incorporate security measures early, according to Alexandra Seymour, associate fellow for the Technology and National Security Program at the Center for New American Security.

“When…we’re able to test technologies and these environments, we’re able to figure out where those vulnerabilities are, so that we’re able to improve them,” Seymour told IT Brew. “So that, by the time we actually do get to deployment, we’ve mitigated a lot of those vulnerabilities.”—BH

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