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Last week the Washington Post reported on how the NSA tracks mobile phones worldwide, and this week they followed up with source documents and more detail.
Barton Gellman and Ashkan Soltani are doing some fantastic reporting on the Snowden NSA documents. I hope to be able to do the same again, once Pierre Omidyar’s media venture gets up and running.
This article talks about applications in retail, but the possibilities are endless.
Every smartphone these days comes equipped with a WiFi card. When the card is on and looking for networks to join, it’s detectable by local routers. In your home, the router connects to your device, and then voila you have the Internet on your phone. But in a retail environment, other in-store equipment can pick up your WiFi card, learn your device’s unique ID number and use it to keep tabs on that device over time as you move through the store.
This gives offline companies the power to get incredibly specific data about how their customers behave. You could say it’s the physical version of what Web-based vendors have spent millions of dollars trying to perfect the science of behavioral tracking.
Basically, the system is using the MAC address to identify individual devices. Another article on the system is here.
There seems to be a bunch of research into uniquely identifying cell phones through unique analog characteristics of the various embedded sensors. These sorts of things could replace cookies as surveillance tools.
Slashdot and MetaFilter threads.
The new iPhone has a motion sensor chip, and that opens up new opportunities for surveillance:
The M7 coprocessors introduce functionality that some may instinctively identify as “creepy.” Even Apple’s own description hints at eerie omniscience: “M7 knows when you’re walking, running, or even driving…” While it’s quietly implemented within iOS, it’s not secret for third party apps (which require an opt-in through pop-up notification, and management through the phone’s Privacy settings). But as we know, most users blindly accept these permissions.
It all comes down to a question of agency in tracking our physical bodies.
The fact that my Fitbit tracks activity without matching it up with all my other data sources, like GPS location or my calendar, is comforting. These data silos can sometimes be frustrating when I want to query across my QS datasets, but the built-in divisions between data about my body —and data about the rest of my digital life—leave room for my intentional inquiry and interpretation.
It’s hard not to poke fun at this press release for Safeslinger, a new cell phone security app from Carnegie Mellon.
“SafeSlinger provides you with the confidence that the person you are communicating with is actually the person they have represented themselves to be,” said Michael W. Farb, a research programmer at Carnegie Mellon CyLab. “The most important feature is that SafeSlinger provides secure messaging and file transfer without trusting the phone company or any device other than my own smartphone.”
Oddly, Farb believes that he can trust his smart phone.
This headline claims that “even [the] NSA can’t crack” it, but it’s unclear where that claim came from.
Still, it’s good to have encrypted chat programs. This one joins Cryptocat, Silent Circle, and my favorite: OTR.
In one of the documents recently released by the NSA as a result of an EFF lawsuit, there’s discussion of a specific capability of a call records database to identify disposable “burner” phones.
Let’s consider, then, the very specific data this query tool was designed to return: The times and dates of the first and last call events, but apparently not the times and dates of calls between those endpoints. In other words, this tool is supporting analytic software that only cares when a phone went online, and when it stopped being used. It also gets the total number of calls, and the ratio of unique contacts to calls, but not the specific numbers contacted. Why, exactly, would this limited set of information be useful? And why, in particular, might you want to compare that information across a large number of phones there’s not yet any particular reason to suspect?
One possibility that jumps out at me—and perhaps anyone else who’s a fan of The Wire—is that this is the kind of information you would want if you were trying to identify disposable prepaid “burner” phones being used by a target who routinely cycles through cell phones as a countersurveillance tactic. The number of unique contacts and call/contact ratio would act as a kind of rough fingerprint—you’d assume a phone being used for dedicated clandestine purposes to be fairly consistent on that score—while the first/last call dates help build a timeline: You’re looking for a series of phones that are used for a standard amount of time, and then go dead just as the next phone goes online.
Consider this another illustration of the value of metadata.
Neat project. The reason it works is that the Android system doesn’t start putting in very long delays between PIN attempts after a whole bunch of unsuccessful attempts. The iPhone does.
Nice hack from the Chaos Computer Club:
The method follows the steps outlined in this how-to with materials that can be found in almost every household: First, the fingerprint of the enrolled user is photographed with 2400 dpi resolution. The resulting image is then cleaned up, inverted and laser printed with 1200 dpi onto transparent sheet with a thick toner setting. Finally, pink latex milk or white woodglue is smeared into the pattern created by the toner onto the transparent sheet. After it cures, the thin latex sheet is lifted from the sheet, breathed on to make it a tiny bit moist and then placed onto the sensor to unlock the phone. This process has been used with minor refinements and variations against the vast majority of fingerprint sensors on the market.
I’m not surprised. In my essay on Apple’s technology, I wrote: “I’m sure that someone with a good enough copy of your fingerprint and some rudimentary materials engineering capability—or maybe just a good enough printer—can authenticate his way into your iPhone.”
I don’t agree with CCC’s conclusion, though:
“We hope that this finally puts to rest the illusions people have about fingerprint biometrics. It is plain stupid to use something that you can´t change and that you leave everywhere every day as a security token”, said Frank Rieger, spokesperson of the CCC. “The public should no longer be fooled by the biometrics industry with false security claims. Biometrics is fundamentally a technology designed for oppression and control, not for securing everyday device access.”
Apple is trying to balance security with convenience. This is a cell phone, not a ICBM launcher or even a bank account withdrawal device. Apple is offering an option to replace a four-digit PIN—something that a lot of iPhone users don’t even bother with—with a fingerprint. Despite its drawbacks, I think it’s a good trade-off for a lot of people.
EDITED TO ADD (10/13): The print for the CCC hack was lifted from the iPhone.
This article points out that as people are logging into Wi-Fi networks from their Android phones, and backing up those passwords along with everything else into Google’s cloud, that Google is amassing an enormous database of the world’s Wi-Fi passwords. And while it’s not every Wi-Fi password in the world, it’s almost certainly a large percentage of them.
Leaving aside Google’s intentions regarding this database, it is certainly something that the US government could force Google to turn over with a National Security Letter.
Something else to think about.
When Apple bought AuthenTec for its biometrics technology—reported as one of its most expensive purchases—there was a lot of speculation about how the company would incorporate biometrics in its product line. Many speculate that the new Apple iPhone to be announced tomorrow will come with a fingerprint authentication system, and there are several ways it could work, such as swiping your finger over a slit-sized reader to have the phone recognize you.
Apple would be smart to add biometric technology to the iPhone. Fingerprint authentication is a good balance between convenience and security for a mobile device.
Biometric systems are seductive, but the reality isn’t that simple. They have complicated security properties. For example, they are not keys. Your fingerprint isn’t a secret; you leave it everywhere you touch.
And fingerprint readers have a long history of vulnerabilities as well. Some are better than others. The simplest ones just check the ridges of a finger; some of those can be fooled with a good photocopy. Others check for pores as well. The better ones verify pulse, or finger temperature. Fooling them with rubber fingers is harder, but often possible. A Japanese researcher had good luck doing this over a decade ago with the gelatin mixture that’s used to make Gummi bears.
The best system I’ve ever seen was at the entry gates of a secure government facility. Maybe you could have fooled it with a fake finger, but a Marine guard with a big gun was making sure you didn’t get the opportunity to try. Disney World uses a similar system at its park gates—but without the Marine guards.
A biometric system that authenticates you and you alone is easier to design than a biometric system that is supposed to identify unknown people. That is, the question “Is this the finger belonging to the owner of this iPhone?” is a much easier question for the system to answer than “Whose finger is this?”
There are two ways an authentication system can fail. It can mistakenly allow an unauthorized person access, or it can mistakenly deny access to an authorized person. In any consumer system, the second failure is far worse than the first. Yes, it can be problematic if an iPhone fingerprint system occasionally allows someone else access to your phone. But it’s much worse if you can’t reliably access your own phone—you’d junk the system after a week.
If it’s true that Apple’s new iPhone will have biometric security, the designers have presumably erred on the side of ensuring that the user can always get in. Failures will be more common in cold weather, when your shriveled fingers just got out of the shower, and so on. But there will certainly still be the traditional PIN system to fall back on.
So…can biometric authentication be hacked?
Almost certainly. I’m sure that someone with a good enough copy of your fingerprint and some rudimentary materials engineering capability—or maybe just a good enough printer—can authenticate his way into your iPhone. But, honestly, if some bad guy has your iPhone and your fingerprint, you’ve probably got bigger problems to worry about.
The final problem with biometric systems is the database. If the system is centralized, there will be a large database of biometric information that’s vulnerable to hacking. A system by Apple will almost certainly be local—you authenticate yourself to the phone, not to any network—so there’s no requirement for a centralized fingerprint database.
Apple’s move is likely to bring fingerprint readers into the mainstream. But all applications are not equal. It’s fine if your fingers unlock your phone. It’s a different matter entirely if your fingerprint is used to authenticate your iCloud account. The centralized database required for that application would create an enormous security risk.
This essay previously appeared on Wired.com.
EDITED TO ADD: The new iPhone does have a fingerprint reader.
Sidebar photo of Bruce Schneier by Joe MacInnis.