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This device is clever: it’s a three-digit combination lock that prevents a USB drive from being read. It’s not going to keep out anyone serious, but is a great solution for the sort of casual security that most people need.
EDITED TO ADD (11/15): Similar products.
Someone recently noticed a Washington Post story on the TSA that originally contained a detailed photograph of all the TSA master keys. It’s now blurred out of the Washington Post story, but the image is still floating around the Internet. The whole thing neatly illustrates one of the main problems with backdoors, whether in cryptographic systems or physical systems: they’re fragile.
Nicholas Weaver wrote:
TSA “Travel Sentry” luggage locks contain a disclosed backdoor which is similar in spirit to what Director Comey desires for encrypted phones. In theory, only the Transportation Security Agency or other screeners should be able to open a TSA lock using one of their master keys. All others, notably baggage handlers and hotel staff, should be unable to surreptitiously open these locks.
Unfortunately for everyone, a TSA agent and the Washington Post revealed the secret. All it takes to duplicate a physical key is a photograph, since it is the pattern of the teeth, not the key itself, that tells you how to open the lock. So by simply including a pretty picture of the complete spread of TSA keys in the Washington Post’s paean to the TSA, the Washington Post enabled anyone to make their own TSA keys.
So the TSA backdoor has failed: we must assume any adversary can open any TSA “lock”. If you want to at least know your luggage has been tampered with, forget the TSA lock and use a zip-tie or tamper-evident seal instead, or attach a real lock and force the TSA to use their bolt cutters.
It’s the third photo on this page, reproduced here. There’s also this set of photos. Get your copy now, in case they disappear.
Reddit thread. BoingBoing post. Engadget article.
EDITED TO ADD (9/10): Someone has published a set of CAD files so you can make your own master keys.
Marte Løge, a 2015 graduate of the Norwegian University of Science and Technology, recently collected and analyzed almost 4,000 ALPs as part of her master’s thesis. She found that a large percentage of them—44 percent—started in the top left-most node of the screen. A full 77 percent of them started in one of the four corners. The average number of nodes was about five, meaning there were fewer than 9,000 possible pattern combinations. A significant percentage of patterns had just four nodes, shrinking the pool of available combinations to 1,624. More often than not, patterns moved from left to right and top to bottom, another factor that makes guessing easier.
EDITED TO ADD (9/10): Similar research on this sort of thing.
Brink’s sells an Internet-enabled smart safe called the CompuSafe Galileo. Despite being sold as a more secure safe, it’s wildly insecure:
Vulnerabilities found in CompuSafe Galileo safes, smart safes made by the ever-reliable Brinks company that are used by retailers, restaurants, and convenience stores, would allow a rogue employee or anyone else with physical access to them to command their doors to open and relinquish their cash….
The hack has the makings of the perfect crime, because a thief could also erase any evidence that the theft occurred simply by altering data in a back-end database where the smartsafe logs how much money is inside and who accessed it.
Nothing about these vulnerabilities is a surprise to anyone who works in computer security:
But the safes have an external USB port on the side of the touchscreens that allows service technicians to troubleshoot and obtain a backup of the database. This, unfortunately, creates an easy entrypoint for thieves to take complete, administrative control of the devices.
“Once you’re able to plug into that USB port, you’re able to access lots of things that you shouldn’t normally be able to access,” Petro told WIRED. “There is a full operating system…that you’re able to…fully take over…and make [the safe] do whatever you want it to do.”
The researchers created a malicious script that, once inserted into a safe on a USB stick, lets a thief automatically open the safe doors by emulating certain mouse and keyboard actions and bypassing standard application controls. “You plug in this little gizmo, wait about 60 seconds, and the door just pops open,” says Petro.
If it sounds like the people who designed this e-safe ignored all of the things we’ve learned about computer security in the last few decades, you’re right. And that’s the problem with Internet-of-Things security: it’s often designed by people who don’t know computer or Internet security.
They also haven’t learned the lessons of full disclosure or rapid patching:
They notified Brinks about the vulnerabilities more than a year ago, but say the company appears to have done nothing to resolve the issues. Although Brinks could disable driver software associated with the USB port to prevent someone from controlling the safes in this way, or lock down the system and database so it’s not running in administrative mode and the database can’t be changed, but so far the company appears to have done none of these.
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Again, this all sounds familiar. The computer industry learned its lessons over a decade ago. Before then they ignored security vulnerabilities, threatened researchers, and generally behaved very badly. I expect the same things to happen with Internet-of-Things companies.
Kamkar told Ars his Master Lock exploit started with a well-known vulnerability that allows Master Lock combinations to be cracked in 100 or fewer tries. He then physically broke open a combination lock and noticed the resistance he observed was caused by two lock parts that touched in a way that revealed important clues about the combination. (He likened the Master Lock design to a side channel in cryptographic devices that can be exploited to obtain the secret key.) Kamkar then made a third observation that was instrumental to his Master Lock exploit: the first and third digit of the combination, when divided by four, always return the same remainder. By combining the insights from all three weaknesses he devised the attack laid out in the video.
Neat, but I’ll bet it can be hacked.
From Betty Medsger’s book on the 1971 FBI burglary (page 22):
As burglars, they used some unusual techniques, ones Davidon enjoyed recalling years later, such as what some of them did in 1970 at a draft board office in Delaware. During their casing, they had noticed that the interior door that opened to the draft board office was always locked. There was no padlock to replace, as they had done at a draft board raid in Philadelphia a few months earlier, and no one in the group was able to pick the lock. The break-in technique they settled on at that office must be unique in the annals of burglary. Several hours before the burglary was to take place, one of them wrote a note and tacked it to the door they wanted to enter: “Please don’t lock this door tonight.” Sure enough, when the burglars arrived that night, someone had obediently left the door unlocked. The burglars entered the office with ease, stole the Selective Service records, and left. They were so pleased with themselves that one of them proposed leaving a thank-you note on the door. More cautious minds prevailed. Miss Manners be damned, they did not leave a note.
The UK has banned researchers from revealing details of security vulnerabilities in car locks. In 2008, Phillips brought a similar suit against researchers who broke the Mifare chip. That time, they lost. This time, Volkswagen sued and won.
This is bad news for security researchers. (Remember back in 2001 when security researcher Ed Felten sued the RIAA in the US to be able to publish his research results?) We’re not going to improve security unless we’re allowed to publish our results. And we can’t start suppressing scientific results, just because a big corporation doesn’t like what it does to their reputation.
EDITED TO ADD (8/14): Here’s the ruling.
Here is a new lock that you can control via Bluetooth and an iPhone app.
That’s pretty cool, and I can imagine all sorts of reasons to get one of those. But I’m sure there are all sorts of unforeseen security vulnerabilities in this system. And even worse, a single vulnerability can affect all the locks. Remember that vulnerability found last year in hotel electronic locks?
Anyone care to guess how long before some researcher finds a way to hack this one? And how well the maker anticipated the need to update the firmware to fix the vulnerability once someone finds it?
I’m not saying that you shouldn’t use this lock, only that you understand that new technology brings new security risks, and electronic technology brings new kinds of security risks. Security is a trade-off, and the trade-off is particularly stark in this case.
Sidebar photo of Bruce Schneier by Joe MacInnis.