Street View cars grabbed locations of phones, PCs
eugen at leitl.org
Wed Jul 27 02:52:02 PDT 2011
July 25, 2011 12:14 AM PDT
Street View cars grabbed locations of phones, PCs
by Declan McCullagh
Some locations that Google associated with Wi-Fi devices spotted in a San
Francisco coffee shop.
scoop Google's Street View cars collected the locations of millions of
laptops, cell phones, and other Wi-Fi devices around the world, a practice
that raises novel privacy concerns, CNET has confirmed.
The cars were supposed to collect the locations of Wi-Fi access points. But
Google also recorded the street addresses and unique identifiers of computers
and other devices using those wireless networks and then made the data
publicly available through Google.com until a few weeks ago.
The French data protection authority, known as the Commission Nationale de
l'Informatique et des Libertis (CNIL) recently contacted CNET and said its
investigation confirmed that Street View cars collected these unique hardware
IDs. In March, CNIL's probe resulted in a fine of 100,000 euros, about
The confirmation comes as concerns about location privacy appear to be
growing. Apple came under fire in April for recording logs of approximate
location data on iPhones, and eventually released a fix. That controversy
sparked a series of disclosures about other companies' location privacy
practices, questions and complaints from congressmen, a pair of U.S. Senate
hearings, and the now-inevitable lawsuits seeking class action status.
A previous CNET article, published June 15 and triggered by the research of
security consultant Ashkan Soltani, was the first to report that Google made
these unique hardware IDs--called MAC addresses--publicly available through a
Web interface. Google curbed the practice about a week later.
But it was unclear at the time whether Google's location database included
the hardware IDs of only access points and wireless routers or client
devices, such as computers and mobile phones, as well.
Anecdotal evidence suggested they had been swept up. Alissa Cooper, chief
computer scientist at the Center for Democracy and Technology and co-chair of
an Internet Engineering Task Force on geolocation, said her 2009 home address
was listed in Google's location database. Nick Doty, a lecturer at the
University of California at Berkeley who co-teaches the Technology and Policy
Lab, found that Google listed his former home in the Capitol Hill
neighborhood in Seattle.
"It would be helpful to have some clarity about why and how (a hardware
address) got in there so people can act accordingly," says Soltani, the
Security researcher Ashkan Soltani says a big problem is no opt-out method.
(Credit: Declan McCullagh/CNET)
Google declined repeated requests for comment for this article over a period
of more than a week. In a statement last month, the search company said only
that "we collect the publicly broadcast MAC addresses of Wi-Fi access
points," which addressed only current and not past practices.
Google does not provide any method, sometimes called an opt-out mechanism,
that would allow people who don't want their unique hardware IDs in the
database to remove them. Instead of using Street View cars, Google new
"crowdsources" its location database by using Android phones.
The most likely explanation of how the Wi-Fi devices were included is the
simplest: Just as an accident of programming led to Street View cars
collecting (in relatively few cases) the contents of unencrypted wireless
communications, client hardware addresses were also vacuumed up. Then they
were added to Google's geolocation database, which was publicly available
without access restrictions until late June.
Wi-Fi-enabled devices, including PCs, iPhones, iPads, and Android phones,
transmit a unique hardware identifier to anyone within a radius of
approximately 100 to 200 feet. If someone captured or already knew that
unique address because they had access to the device, Google's application
programming interface, or API, revealed where that device was located, a
practice that can reveal personal information including home or work
addresses or even the addresses of restaurants frequented.
To be sure, it's not always easy to learn a target's MAC address. It's
generally not transmitted over the Internet. But anyone within Wi-Fi range
can record it, and it's easy to narrow down which MAC addresses correspond to
which manufacturer. Someone, such as a suspicious spouse, who can navigate to
the About screen on an iPhone can obtain it that way too.
Kim Cameron, Microsoft's chief identity architect until earlier this year,
had long suspected that Street View cars vacuumed up the hardware addresses
of devices using a Wi-Fi connection. In a June 2010 essay that analyzed an
independent report (PDF) of Street View data collection, Cameron said he
believed that Google recorded the locations and MAC addresses of far more
than just fixed Wi-Fi access points.
Marc Rotenberg, head of the Electronic Privacy Information Center in
Washington, D.C., said he has concerns about the legality of intercepting the
hardware addresses of devices using Wi-Fi connections.
"The fact that other companies such as Skyhook may have engaged in this
behavior, which seems to be Google's best defense, doesn't make it lawful,"
Rotenberg said. "What it does suggest is that there's more to the
investigation of Street View."
In the U.S., the Federal Trade Commission ended its investigation of Street
View's accidentally-broad data collection last October without levying a
Disclosure: McCullagh is married to a Google employee not involved in this
Starting in April, CNET posed a series of questions to Google that have gone
unanswered. A Google spokesman said that "we have talked extensively about
geolocation privacy, before two senate panels and elsewhere," but declined to
elaborate. Here's an abbreviated list of our questions:
- How was this database of client MAC addresses assembled -- Street View
cars or Android phones, or both?
- Are you still adding to this database of client MAC addresses, or was
its collection halted as part of the response to Street View concerns? If you
did stop, when?
- Are you planning to continue to offer this geolocation data? If not,
will you irrevocably delete it?
- For what countries have you collected geolocation data of client MAC
- How many client MAC addresses do you have in your geolocation database?
- The 802.11/WiFi header allows client devices to be differentiated from
access points (APs are reported in the BSSID field of the WiFi header). Why
did Google record and make available client device geolocation information
rather than access point geolocation info?
- Can you tell me how many client (non-AP) MAC addresses you have in your
- It appears that iPhones in AP mode use addresses in the unassigned
range of B2:27:E4, which is not the normal Wi-Fi client MAC address space.
Why don't you filter that range?
- Is Street View the only mechanism through which client (non-AP) MAC
addresses were added to your geolocation database?
- When did you cease adding client MAC addresses to your database?
- Why did you not scrub client MAC addresses, which aren't useful for
geolocation, from your database after the CNIL's investigation?
- Have you permanently deleted client MAC addresses from your database
after my initial CNET article appeared?
- Why doesn't Google randomize those two 16-byte strings (let's call them
the device ID) on an hourly or daily basis? [Ed. Note: This is a reference to
two 16-byte strings representing a device ID unique to each phone.]
- Given a street address or pair of GPS coordinates, is Google able to
produce the complete location logs associated with that device ID, if legally
required to do so?
- Given a device ID, is Google able to produce the complete location logs
associated with it, if legally required to do so?
- Given a MAC address of an access point, is Google able to produce the
device IDs and location data associated with it, if legally required to do
- How long are these location logs and device ID logs kept?
- If they are partially anonymized after a certain time, how is that
done, and can those records be restored from a backup if Google is legally
required to do so?
- How many law enforcement requests or forms of compulsory process have
you received for access to any portion of this database?
- How are the device ID strings calculated?
- If Google knows that a Gmail user is connecting from a home network IP
address every evening, it would be trivial to link that with an Android
phone's device ID that also connects via that IP address. Does Google do
More information about the cypherpunks-legacy