All the Ways Your Wi-Fi Router Can Spy on You
GrayRider
Warning: Sensitive/Creepy Material
City dwellers spend nearly every moment of every day awash
in Wi-Fi signals. Homes, streets, businesses, and office buildings are
constantly blasting wireless signals every which way for the benefit of
nearby phones, tablets, laptops, wearables, and other connected
paraphernalia.
When those devices connect to a router, they send requests
for information—a weather forecast, the latest sports scores, a news
article—and, in turn, receive that data, all over the air. As it
communicates with the devices, the router is also gathering information
about how its signals are traveling through the air, and whether they’re
being disrupted by obstacles or interference. With that data, the
router can make small adjustments to communicate more reliably with the
devices it’s connected to.
But it can also be used to monitor humans—and in surprisingly detailed ways.
As people move through a space with a Wi-Fi signal, their
bodies affect it, absorbing some waves and reflecting others in various
directions. By analyzing the exact ways that a Wi-Fi signal is altered
when a human moves through it, researchers can “see” what someone writes
with their finger in the air, identify a particular person by the way
that they walk, and even read a person’s lips with startling accuracy—in
some cases even if a router isn’t in the same room as the person
performing the actions.
Several recent experiments have focused on using Wi-Fi
signals to identify people, either based on their body shape or the
specific way they tend to move. Earlier this month, a group of
computer-science researchers at Northwestern Polytechnical University in
China posted a paper
to an online archive of scientific research, detailing a system that
can accurately identify humans as they walk through a door nine times
out of ten.
The system must first be trained: It has to learn
individuals’ body shapes so that it can identify them later. After
memorizing body shapes, the system, which the researchers named
FreeSense, watches for people walking across its line of sight. If it’s
told that the next passerby will be one of two people, the system can
correctly identify which it is 95 percent of the time. If it’s choosing
between six people, it identifies the right one 89 percent of the time.
The researchers proposed using their technology in a
smart-home setting: If the router senses one person’s entry into a room,
it could communicate with other connected devices—lights, appliances,
window shades—to customize the room to that person’s preferences.
FreeSense mirrored another Wi-Fi-based identification system that a group of researchers from Australia and the UK presented at a conference
earlier this year. Their system, Wi-Fi ID, focused on gait as a way to
identify people from among a small group. It achieved 93 percent
accuracy when choosing among two people, and 77 percent when choosing
from among six. Eventually, the researchers wrote, the system could
become accurate enough that it could sound an alarm if an unrecognized
intruder entered.
Something in the way? No problem. A pair of MIT researchers
wrote in 2013 that they could use a router to detect the number of
humans in a room and identify some basic arm gestures, even through a wall.
They could tell how many people were in a room from behind a solid
wooden door, a 6-inch hollow wall supported by steel beams, or an 8-inch
concrete wall—and detect messages drawn in the air from a distance of
five meters (but still in another room) with 100 percent accuracy.
(Using more precise sensors, the same MIT researchers went on to develop systems that can distinguish between different people standing behind walls, and remotely monitor breathing and heart rates
with 99 percent accuracy. President Obama got a glimpse of the latter
technology during last year’s White House Demo Day in the form of Emerald,
a device geared towards elderly people that can detect physical
activity and falls throughout an entire home. The device even tries to
predict falls before they happen by monitoring a person’s movement
patterns.)
Beyond human identification and general gesture
recognition, Wi-Fi signals can be used to discern even the slightest of
movements with extreme precision.
A system called “WiKey” presented at a conference last year could tell what keys a user was pressing on a keyboard
by monitoring minute finger movements. Once trained, WiKey could
recognize a sentence as it was typed with 93.5 percent accuracy—all
using nothing but a commercially available router and some custom code
created by the researchers.
And a group of researchers led by a Berkeley Ph.D. student presented technology at a 2014 conference that could “hear” what people were saying
by analyzing the distortions and reflections in Wi-Fi signals created
by their moving mouths. The system could determine which words from a
list of lip-readable vocabulary were being said with 91 percent accuracy
when one person was speaking, and 74 percent accuracy when three people
were speaking at the same time.
Many researchers presented their Wi-Fi sensing technology
as a way to preserve privacy while still capturing important data.
Instead of using cameras to monitor a space—recording and preserving
everything that happens in detail—a router-based system could detect
movements or actions without intruding too much, they said.
I asked the lead researcher behind WiKey, Kamran Ali,
whether his technology could be used to secretly steal sensitive data.
Ali said the system only works in controlled environments, and with
rigorous training. “So, it is not a big privacy concern for now, no
worries there,” wrote Ali, a Ph.D. student at Michigan State University,
in an email.
But as Wi-Fi “vision” evolves, it may become more adaptable
and need less training. And if a hacker is able to gain access to a
router and install a WiKey-like software package—or trick a user into
connecting to a malicious router—he or she can try to eavesdrop on
what’s being typed nearby without the user ever knowing.
Since all of these ideas piggyback on one of the most ubiquitous
wireless signals, they’re ripe for wide distribution once they’re
refined, without the need for any new or expensive equipment. Routers
could soon keep kids and older adults safe, log daily activities, or
make a smart home run more smoothly—but, if invaded by a malicious
hacker, they could also be turned into incredibly sophisticated hubs for
monitoring and surveillance.http://www.theatlantic.com/technology/archive/2016/08/wi-fi-surveillance/497132/
