Entries Tagged "cell phones"

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Identifying People from Mobile Phone Location Data

Turns out that it’s pretty easy:

Researchers at the Massachusetts Institute of Technology (MIT) and the Catholic University of Louvain studied 15 months’ worth of anonymised mobile phone records for 1.5 million individuals.

They found from the “mobility traces” – the evident paths of each mobile phone – that only four locations and times were enough to identify a particular user.

“In the 1930s, it was shown that you need 12 points to uniquely identify and characterise a fingerprint,” said the study’s lead author Yves-Alexandre de Montjoye of MIT.

“What we did here is the exact same thing but with mobility traces. The way we move and the behaviour is so unique that four points are enough to identify 95% of people,” he told BBC News.

Here’s the study.

EFF maintains a good page on the issues surrounding location privacy.

Posted on March 26, 2013 at 6:38 AM • View Comments

Text Message Retention Policies

The FBI wants cell phone carriers to store SMS messages for a long time, enabling them to conduct surveillance backwards in time. Nothing new there—data retention laws are being debated in many countries around the world—but this was something I did not know:

Wireless providers’ current SMS retention policies vary. An internal Justice Department document (PDF) that the ACLU obtained through the Freedom of Information Act shows that, as of 2010, AT&T, T-Mobile, and Sprint did not store the contents of text messages. Verizon did for up to five days, a change from its earlier no-logs-at-all position, and Virgin Mobile kept them for 90 days. The carriers generally kept metadata such as the phone numbers associated with the text for 90 days to 18 months; AT&T was an outlier, keeping it for as long as seven years.

An e-mail message from a detective in the Baltimore County Police Department, leaked by Antisec and reproduced in a 2011 Wired article, says that Verizon keeps “text message content on their servers for 3-5 days.” And: “Sprint stores their text message content going back 12 days and Nextel content for 7 days. AT&T/Cingular do not preserve content at all. Us Cellular: 3-5 days Boost Mobile LLC: 7 days”

That second set of data is from 2009.

Leaks seems to be the primary way we learn how our privacy is being violated these days—we need more of them.

EDITED TO ADD (4/12): Discussion of Canadian policy.

Posted on March 21, 2013 at 1:17 PM • View Comments

How the FBI Intercepts Cell Phone Data

Good article on “Stingrays,” which the FBI uses to monitor cell phone data. Basically, they trick the phone into joining a fake network. And, since cell phones inherently trust the network—as opposed to computers which inherently do not trust the Internet—it’s easy to track people and collect data. There are lots of questions about whether or not it is illegal for the FBI to do this without a warrant. We know that the FBI has been doing this for almost twenty years, and that they know that they’re on shaky legal ground.

The latest release, amounting to some 300 selectively redacted pages, not only suggests that sophisticated cellphone spy gear has been widely deployed since the mid-’90s. It reveals that the FBI conducted training sessions on cell tracking techniques in 2007 and around the same time was operating an internal “secret” website with the purpose of sharing information and interactive media about “effective tools” for surveillance. There are also some previously classified emails between FBI agents that show the feds joking about using the spy gear. “Are you smart enough to turn the knobs by yourself?” one agent asks a colleague.

Of course, if a policeman actually has your phone, he can suck pretty much everything out of it—again, without a warrant.

Using a single “data extraction session” they were able to pull:

  • call activity
  • phone book directory information
  • stored voicemails and text messages
  • photos and videos
  • apps
  • eight different passwords
  • 659 geolocation points, including 227 cell towers and 403 WiFi networks with which the cell phone had previously connected.

Posted on March 7, 2013 at 1:39 PM • View Comments

Guessing Smart Phone PINs by Monitoring the Accelerometer

“Practicality of Accelerometer Side Channels on Smartphones,” by Adam J. Aviv. Benjamin Sapp, Matt Blaze, and Jonathan M. Smith.

Abstract: Modern smartphones are equipped with a plethora of sensors that enable a wide range of interactions, but some of these sensors can be employed as a side channel to surreptitiously learn about user input. In this paper, we show that the accelerometer sensor can also be employed as a high-bandwidth side channel; particularly, we demonstrate how to use the accelerometer sensor to learn user tap and gesture-based input as required to unlock smartphones using a PIN/password or Android’s graphical password pattern. Using data collected from a diverse group of 24 users in controlled (while sitting) and uncontrolled (while walking) settings, we develop sample rate independent features for accelerometer readings based on signal processing and polynomial fitting techniques. In controlled settings, our prediction model can on average classify the PIN entered 43% of the time and pattern 73% of the time within 5 attempts when selecting from a test set of 50 PINs and 50 patterns. In uncontrolled settings, while users are walking, our model can still classify 20% of the PINs and 40% of the patterns within 5 attempts. We additionally explore the possibility of constructing an accelerometer-reading-to-input dictionary and find that such dictionaries would be greatly challenged by movement-noise and cross-user training.

Article.

Posted on February 15, 2013 at 6:48 AM • View Comments

Anti-Surveillance Clothing

It’s both an art project and a practical clothing line.

…Harvey’s line of “Stealth Wear” clothing includes an “anti-drone hoodie” that uses metalized material designed to counter thermal imaging used by drones to spot people on the ground. He’s also created a cellphone pouch made of a special “signal attenuating fabric.” The pocket blocks your phone signal so that it can’t be tracked or intercepted by devices like the covert “Stingray” tool used by law enforcement agencies like the FBI.

Posted on January 14, 2013 at 1:27 PM • View Comments

Apple Turns on iPhone Tracking in iOS6

This is important:

Previously, Apple had all but disabled tracking of iPhone users by advertisers when it stopped app developers from utilizing Apple mobile device data via UDID, the unique, permanent, non-deletable serial number that previously identified every Apple device.

For the last few months, iPhone users have enjoyed an unusual environment in which advertisers have been largely unable to track and target them in any meaningful way.

In iOS 6, however, tracking is most definitely back on, and it’s more effective than ever, multiple mobile advertising executives familiar with IFA tell us. (Note that Apple doesn’t mention IFA in its iOS 6 launch page).

EDITED TO ADD (10/15): Apple has provided a way to opt out of the targeted ads and also to disable the location information being sent.

Posted on October 15, 2012 at 1:21 PM • View Comments

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Sidebar photo of Bruce Schneier by Joe MacInnis.