[BreachExchange] Strava’s privacy PR nightmare shows why you can’t trust social fitness apps to protect your data

Audrey McNeil audrey at riskbasedsecurity.com
Mon Jan 29 21:15:14 EST 2018


For years, I used the popular activity-tracking app Strava to log my bike
rides, almost all of which started and ended at my San Francisco apartment.
At some point I thought, hey, maybe it’s not a great idea to share such
precise data about my location, so I set up an online perimeter several
blocks in diameter around my home to make the beginning and end of my
journey a little less obvious. That way, the app wouldn’t show my movements
once I’d entered that zone.

Millions of Strava’s other users clearly aren’t as wary. Late last year,
the company released a searchable heat map based on a billion
activitieslogged publicly by its users. Researchers have now shown that the
data can be used to reveal the location of sensitive sites like US military
basesin countries such as Afghanistan and Syria, as well as the exercise
routines of their occupants. Chances are that most of the people using
Strava in these places are soldiers and other military personnel, so it
stands to reason that the handful of little bright areas on otherwise dark
portions of a map show where they’re hanging out and moving around. Strava
did not return a request for comment.

This is a security risk for the military, which in response is apparently
updating its rules about how gadgets are used at its sites. For the rest of
us, it’s an important reminder that tech companies that urge you to track
aspects of your life and share them with other people really don’t want you
to keep those tidbits private. Many, like Strava, Facebook, and Twitter,
have made sharing a cornerstone of their business models. For the
foreseeable future, you’ll need to figure out for yourself what to keep
private and what is safe to share—which is often quite difficult to
determine, much less act upon.

Strava needs its users to share their rides, runs, and swims. After all,
the more activities they share—currently users post over 1.3 million
activities per day—the more evidence Strava has to encourage others to keep
using the app, and perhaps even trade up from the free version to an
$8-per-month one. More shared data also means more to feed into Strava’s
Metro business, which sells anonymized commuter data to cities. The company
wasn’t profitable as of this past fall, but its CEO, James Quarles, clearly
sees these two lines of business as the main paths to growth, assuming it
gets more and more information from its users.

And, frankly, using Strava in a very social way can be addicting. Since it
began, in 2009, the company has perfected the art of fitness gamification
and competitive sharing. Its app lets you see basic stats from your and
your friends’ workouts; it encourages you to give each other kudos for
completing activities; it gives awards for things like getting your best
time on a specific segment of a bike ride or completing it faster than
other riders. You can drill down on specific bits of a ride or run to see
how you or others stack up. And this is all stuff you can do without even
paying for the app—the premium version gives you access to additional
features like a “suffer score” that analyzes your heart rate.

You might not want to share everything you’re doing on Strava, though. This
isn’t only a matter of personal privacy. As Beau Woods, cyber safety
innovation fellow at the Atlantic Council, points out, there are
significant implications when it comes to sharing collective data,
especially if a person or group of people traces the same path over and
over. The military has just had a big wake-up call about this risk.

Doing something about this isn’t that easy. While Strava includes tons of
straightforward ways to look at the data its community has collected, it’s
actually rather difficult to find, understand, and use its privacy
settings. For instance, in Strava’s iOS app you can tap the “More” tab at
the bottom right of the app, then tap “Settings,” and then “Privacy,” to
find a bunch of sliders. (You can also get there by tapping the “Feed” tab
and then hitting “You” to see a prompt to go to your privacy settings.)
Prominently placed at the top of the privacy settings page is an “Enhanced
Privacy” option. This is turned off by default, and when it’s off it means
anyone can see your Strava profile and photos. Other Strava users who are
logged in can follow you and, perhaps most important, view and download any
activities you log with the app.

That’s not to say that turning on “Enhanced Privacy,” as I’ve done, means
you are hidden on the site. Your activities won’t show up on your profile
page, but you’ll still need to mark them as private to ensure they don’t
show up in other parts of Strava’s data-rich universe—for example, in the
leaderboards that are connected to run and ride segments. To make
activities private by default, you’ll have to use that slider (and it will
only make new activities private by default). You can’t set up a perimeter
around your home base to cloak it unless you go onto Strava’s website,
which is a pain if, like many of us, you’re mostly using the service on
your phone.

Part of the reason I share on fitness apps is that it feels good to let
people know I got out there and had fun (and suffered!) doing something
good for my body and my mind. And it feels good to get the kudos,
especially from friends with much more impressive levels of fitness. Yet
there’s a very real cost to this sharing, so it’s vital that we take the
time to slog through our apps and figure out what we’re getting and what
we’re giving up, and then adjust how we use them (and how they use us)

Which reminds me—since I recently moved, I need to go onto Strava’s website
and create a new safety perimeter before I head out on my next ride.
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