How to Prevent a Coffee Shop Wi-Fi Attack

The world just got a bit riskier for us “road warriors.” You see, there’s
this perfect storm of risks lined up to make our lives a little more dangerous.
Here’s why, and here’s what we can do to fight back.

In the last couple years, a new breed of mobile user has sprung up. Thanks in
large part to the iPhone (and the iPhone-wannabees), the world now has a lot
more mobile devices hungry for a live (and free) Wi-Fi connection. Sure, we’ve
been using Wi-Fi for years, but at least for many of us, what was once the
casual and even occasional laptop login has become a more convenient and far
more frequent quick check for email, stock reports, headlines, etc.

We’re using our hyper-mobile devices all the time now. Standing in line at
the coffee shop, we quickly fire up our pocket-sized devices to see what’s going
on in the world.

Now, here’s where the risk storm comes in.

When you point your Wi-Fi interface at a local wireless access point (WAP),
you’re implicitly trusting it. Say, for example, you’re in your favorite coffee
shop and turn on your mobile device and see there’s a Wi-Fi net present—say,
something like “Acme-wireless.” You see it’s not using WEP, so you blindly and
courageously take the leap of faith and connect to it.

Once on the wireless, you bring up your browser and try to connect to a Web
site. Looks fine, so you login to that web site, perhaps providing your login
credentials (or a browser-stored cookie containing your login credentials). Away
you go—and away your login credentials go. You’ve just fallen for the oldest
trick in the book, the dreaded “man in the middle attack,” and your attacker now
has your credentials/cookie.

How could that have happened, you ask? Well, when you signed onto
“Acme-wireless,” you trusted that it was indeed “Acme-wireless” and that it is
operated by an honest business. The only proof you had that it was indeed
“Acme-wireless” was that it said so.

You’ve been duped.

Yes, it’s easy to do. It would be absolutely simple to configure a laptop PC
to masquerade as “Acme-wireless” and then to collect login credentials from
unsuspecting mobile users seeking a free Wi-Fi fix. After all, the Wi-Fi
standard provides no mechanism for the user to authenticate the server. None.
Nada. Zip.

And that’s just one kind of Wi-Fi-based attack. It gets worse. When you
connect over Wi-Fi, a lot of relatively sensitive information (e.g., passwords,
session IDs, cookies) is routinely passed unencrypted and is thus open to being
trivially sniffed by anyone else on the same Wi-Fi site. That person sitting
next to you in the coffee shop could well be running a sniffing tool like Wireshark and collecting anything sensitive
that your browser or email client emits.

Now, combine all that with the fact that our hyper-mobile devices are getting
smaller and smaller, while at the same time becoming more and more capable as
powerful computing devices. Further, we’re starting to trust them more and more
for connecting to sensitive network services, including financial services and
such. That is to say that they are without a doubt becoming serious targets by
the miscreants of the world who want to liberate your money from your wallet.

Next page: How to Protect Yourself

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