This year at Black Hat I’m presenting some short work on breaking electronic door locks. This talk focuses on one particular residential door lock. There was a bit of a flaw in the design, where the front panel/keypad can be removed from the outside.
Once the keypad is off, you have access to a connector that goes into the rear side of the device. You can then make a cool “brute force” board, which was basically the point of this presentation. Finally you can have something that looks like your movie electronic lock hacking mechanism, completed with 7-segment LED displays:
This little device does the following:
Emulates the front-panel keyboard.
Sends a number of guesses into the lock in quick succession.
Resets the backend lock to bypass the timeout mechanism when too many wrong guesses are put in.
The last part of the attack is the one that makes this a “vaguely useful” attack. The reset process is a little slow, but fast enough you could brute-force the 4-digit code in about 85 mins.
If you wanted to replace the external keyboard (so the owner didn’t know you were playing with it), it’s potentially possible but it requires very good conditions at best (i.e., good lighting, good angle, proper tools). For my demos I’ve added some restraints around the connector to make it more stationary such I can replace the keyboard without these tools.
As you can image, any “real” attacker is likely to use existing entry methods (bypass door, drill lock, kick down etc) instead of this slow/exotic attack. Despite this low risk the vendor is working on a fix. It sounds to be a VERY robust fix too, this isn’t a small change to stop only my specific board/attack either.
Hopefully this talk helps show various design teams about where people might be probing their products. Sometimes it’s just a little change in perspective is all it takes. Design engineers are often in the mindset of “design within given parameters”, but attackers are going to be looking outside of those design specs for weaknesses. Once you give the design engineer the perspective of considering the front-panel removable & a hostile environment for example, they may come up with all sorts of other attacks I didn’t think of (and thus will improve the products to prevent this).
Ultimately I think it will help consumers win, since they can be more confident that important products (such as these electronic locks) are at least as strong as an old mechanical lock.
If you’ve seen my presentations anytime over the past few years, you’ll know the introduction about “PhD Student at Dalhousie University finishing ‘soon'” has been the claim for the past several years. Finally ‘soon’ actually happened!
You can see my complete thesis entitled “A Framework for Embedded Hardware Security Analysis” on the DalSpace website. It’s been a ton of fun doing the PhD, and I’ve had a lot of help over the years which I’ve very grateful for. For the foreseeable future I’ll be continuing to spin up NewAE Technology Inc., and keeping my ChipWhisperer project alive.
This is just a quick blog post to update you on some rather interesting research that will be coming out led by Eyal Ronen. At Black Hat USA 2016 I did some teardown of the Philips Hue system, and described the possibility of a lightbulb worm.
Check this landing page which now has a draft PDF of what that became. This draft paper details how you can (1) recover the encryption keys used to encrypt the firmware updates, and thus encrypt/sign your own images, and (2) details a bug specific to a version of a range-checking protocol which allows reflashing of bulbs over longer distances. The end result is this basically solves all the roadblocks I had identified as stopping the lighbulb worm from actually happening [NB: the distance-check bug has been FIXED already in firmware updates which solves this specific spreading vector].
To me the most interesting part is a demonstration of side-channel power analysis being useful for breaking a rather good encrypted bootloader. To be clear the Philips Hue does a great job of implementing a bootloader on an IoT device… it’s one of the better I’ve seen, especially considering we are talking about a lightbulb. But it’s very very difficult to hide from side-channel power analysis and other “hands on” embedded hardware attacks, instead it’s better (but more expensive logistically) to push the solutions to the higher-level architecture. If each bulb had a unique encryption key (maybe derived from the MAC address using an algorithm on a secure server if you don’t want to store all those keys) it would provide an excellent layer of defense.
I’m working on making a description of the AES-CCM attack, which will be posted to the wiki page.
Q: What does that mean to someone using Hue, is it safe?
A: Philips released a OTA update to fix the bug that allows spreading over longer distances (October 3rd update). This is a great example of a fast response by a company who takes this stuff seriously. Basically – if I was choosing a smart light platform, I’d probably use Hue (I have a few of them in my house too).
Q: What’s power analysis?
A: This isn’t a FAQ type answer – but you can see an intro video I made. Basically we use tiny variations in power consumption of a device as it’s running to determine information about secrets held within the device.
Q: What if I want more information?
A: Please contact Eyal for more details, if you want to discuss specific questions, etc. Note the Philips-specific details (such as scripts, keys, etc) will never be released, please don’t ask for them.
Q: Does a worm exist?
A: NO. It would be extremely reckless to make such a worm, as it would be VERY hard to contain the spread should you have a bunch of Hue devices around you. Instead that research paper demo’d all the pieces, but stopped short of putting them together (we wouldn’t want a criticality accident).
If you were at the talk, you would have also seen mention that you’ll want to keep your eyes out for future publications by Eyal Ronen. You can see his website for more research related to the Hue as well, and follow him on twitter @eyalr0. He’s been doing some work in parallel that I think will do more than just R.E. the bulbs (as I did), and actually bring some of my `possible’ attacks to become real proof-of-concepts.
Summary of the work (to make it clear):
I did NOT make a worm. The title was a question someone asked me, and the talk is about the security of the Hue.
The mention of a possible ‘Long Range Take Over’ was new/unreleased research by Eyal Ronen – do not credit me with that. It’s part of a larger research publication that will get released at some point.
Philips did a rather good job (all things considered). The only trade-off I really call out is reuse of encryption keys across all FW updates for all devices, which is basically what makes a theoretical worm possible.
Rooting the Hue (earlier post) is a local attack and very nice for hardware hackers. There are unique root passwords which is a great security step, so far I haven’t found flaws in the Hue Bridge 2.0 besides that.
There’s a lot of “interesting vectors” which the talk goes over. Given enough time some of them may give, but it’s a question of who is motivated enough to spend a lot of time on them.
This is a quick post to link to slides from my Black Hat USA 2016 work.
This work stands directly on the work done by Joffrey Czarny & Raphaël Rigo presented at HardWear.io last year (2015). They discovered the issues w.r.t. the stream-mode cipher being used by all manufactures on the MB86C311A, and the fact that secrets are stored on the HD itself. Their work is available at:
This post will briefly show you how to get a root console on the new Philips Hue Bridges (the square ones). It’s rather easy, the only special tools you require are a USB-Serial cable & a torx screwdriver.
There’s a video with full details, this post is just the specifics if you don’t want a very boring walk-through:
For the serial cable (a standard 3.3V type one, DO NOT use a 5V cable), there is a 6-pin header along the bottom. Pin ‘1’ has a square footprint, and counting from pin 1 the connections are:
Pin 1 = GND
Pin 4 = RX In (connect to TX Out of your serial cable)
Pin 5 = TX Out (connect to RX in of your serial cable).
The bottom left-corner of the 2-row header is GND. You’ll have to short that with a wire to the following test point:
To get the system working, check you are getting boot messages. Now, restart the system and after you get a bit of output, short the pin. You might see some output like this:
U-Boot 1.1.4 (Sep 8 2015 - 04:08:21)
bsb002 - Honey Bee 2.0DRAM:
Honey Bee 2.0
ath_ddr_initial_config(195): (16bit) ddr2 init
tap = 0x00000003
Tap (low, high) = (0x8, 0x22)
Tap values = (0x15, 0x15, 0x15, 0x15)
Top of RAM usable for U-Boot at: 84000000
Reserving 214k for U-Boot at: 83fc8000
Reserving 192k for malloc() at: 83f98000
Reserving 44 Bytes for Board Info at: 83f97fd4
Reserving 36 Bytes for Global Data at: 83f97fb0
Reserving 128k for boot params() at: 83f77fb0
Stack Pointer at: 83f77f98
Now running in RAM - U-Boot at: 83fc8000
Flash Manuf Id 0xc8, DeviceId0 0x40, DeviceId1 0x13
flash size 0MB, sector count = 8
Flash: 512 kB
*** Warning *** : PCIe WLAN Module not found !!!
Fetching MAC Address from 0x83febe80
Fetching MAC Address from 0x83febe80
ath_gmac_enet_initialize: reset mask:c02200
Scorpion ---->S27 PHY*
S27 reg init
: cfg1 0x800c0000 cfg2 0x7114
athrs27_phy_setup ATHR_PHY_CONTROL 4 :1000
athrs27_phy_setup ATHR_PHY_SPEC_STAUS 4 :10
Which will then fall back to a prompt:
Good news! We can now get everything working for you. You can print the existing variables if you wish:
Set a boot delay such we can enter the menu without the boot hack:
setenv bootdelay 3
Check it works with
and confirm you get a line like this:
Finally, save the setting with:
You can now reset the system (use the ‘reset’ command), and confirm there is a count-down that gives you time to hit “enter” and get this prompt again.
Now let’s fix the root password. Before doing this, I suggest you keep a copy of the old value:
This would let you restore things back to default. Then the following will set the root password to ‘toor’:
You may have to copy this into notepad first to ensure it all fits on one line! The quotes are critical here. Again check it works with printenv, then type saveenv to store things to disk.
If you want your own password, simply use the ‘mkpasswd’ command in Linux to generate an appropriate string.
NOTE: My original instructions (and the video) had a different ‘setenv’ command, which used SHA1 to hash the password. It turns out this stops ssh from working, so instead as suggested in the comments you can use the above MD5 hash which should work better. For posterity my original instructions were:
This will open the telnet port & start the daemon on boot. Write the file and quit with :wq. You may also want to add the /etc/rc.local to the /etc/sysupgrade.conf file to avoid it being overwritten in the future.
See the comments below – someone found a way to get ‘dropbear’ to allow root login too. It’s great as SSH is much nicer to work with than telnet! This requires a different password hash than my original instructions/video.
Try using telnet to connect now. You can find the IP of the bridge using ifconfig, but you can also get it through the Hue app.You can also try using “Philips-hue.local”, which I’d first check via ping to see if it resolves:
I’ve done the 25-July-2016 update without issue too (after first rooting the hub with an earlier version). I’ll continue to update this as updates happen.
BONUS – How did I figure this out?
The “bomb out to uboot prompt” is a known bug. Once in the prompt, I could edit the bootarg command with this:
This gives me a shell which doesn’t require a login. But many things are broken/disabled in this mode. It was however enough to find that there is another script that runs on startup which uses the uboot env variable, and copies it into the shadow file for the root password.
With this knowledge it’s easy to use mkpasswd to make an appropriate shadow file entry. Easy!
I also checked with two different Hue Bridge v2.0 devices. They contained different root passwords (at least different salts). I’ve been told the root passwords are indeed unique per device, which is a good step to stop someone from attacking your virgin Philips Hue 2.0 bridge.
As an interesting note – other people have also discovered this independently of me. Between writing this post & actually linking it from anywhere (i.e., so you could actually find it) pepe2k figured out the same thing on a forum post.
As well someone else did this same “overwrite root” attack already, but had used an external programmer to write the FLASH memory chip:
@colinoflynn Nice! I broke into mine by modifying the u-boot env in flash (before first turning it on). I’m guessing your way in was cooler?
This summer, our summer intern Greg d’Eon made a quick project to build a X-Y Scanner from a 3D printer (by ‘quick’, I mean it took him less than 2 days!). You can see the source code up on GitHub. Anyway, 3D printers are very nice as they have fairly high resolution and fairly low cost. Here’s a quick video:
We’re using it to measure EM emissions frequencies over a PCB, but you could also use this for side-channel emissions, or fault injection. While the resolution might not be high enough for getting at specific features on a chip surface, it can still be used for general positioning.
With your EM emissions, you can graph X-Y vs. amplitude – here I’ve constrained the range to get an idea where the 96 MHz emissions are concentrated. Probably more interesting would have been to use a 2D plot with colour overlaid over the PCB design:You can also do things like plot frequency vs. position with strength of the signal given by color. In the following graph the X position is fixed, and only the Y position is varied. You can see here the 96MHz oscillator of the SAM3U microcontroller on the ChipWhisperer-Lite for example:
The following blog post shows some details of my SMD soldering process. This was based on a larger video I did (linked below) showing the entire soldering process.
Video of Soldering Setup
The following shows me soldering a complete board with BGA device.
In the above video, there are several pieces of equipment used. The following shows you some of the important ones.
I’m using a T962A reflow oven. I recommend this over the T962, which is a smaller version. The T962A has 3 heat lamps so has a more even heat distribution. Be aware you can’t use the full surface area – about the middle half I find is successful, but depends a little on complexity of the PCB.
I specifically purchased mine from this seller on AliExpress, check other sellers as prices change over time. You might turn it on quickly to confirm it works, but before doing much there are some important fixes:
Removing masking tape, replace with Kapton (Polymide) tape. See instructables post for details.
Updating the firmware and adding a cold-junction sensor. This is the most complex task, and requires soldering a DS18B20 to the mainboard, then using a USB-Serial adapter to reflash the firmware. See the front page of the T962-Improvements Github Repo, which has links to the required soldering. There is also an optional fix to reduce the very noisy small fan.
I built a fume hood out of the following:
2×4’s for frame.
Thick plastic drop-sheet.
Powerful vent booster fan with variable speed control.
Active charcoal oven range hood filter (mounted in top of fume hood).
Active charcoal filter for car cabin (mounted in cardboard box used as exhaust).
You can also improve one out of a range hood from an oven. See video for general fume hood construction.
This requires three things:
Vacuum pump, which you can make from a Tetra Whisper pump (see instructables link). Get some of the nice silicon tubing at the same time (like $3 from Amazon).
Syringe with hole drilled into body. You can get syringes (don’t need the pointy bit!) from pharmacy, or order from Newark/Digikey. When you cover the hole, you force the vacuum through the tip, picking up the part. Release your finger from the hole to drop the part. See the above video for details.
The tips for pick and place, which are “Luer Lock” needles bent slightly (for small parts) or commercially available tips (for larger parts).
The tips are the only somewhat tricky thing. I had a good selection from a previous SMD picker tool, something like this kit for example (which is Chip Quick Inc. part #V8910). These tips are actually the same “Luer Lock” that fits into syringes, check E-Bay for cheaper kits:
You can also buy Chip Quik Inc part #VCS-9-B which has a bunch of these tips. It’s not the cheapest way, but if you are in a hurry will do! But all of these tips are for larger parts (i.e. maybe SOT23-3 at smallest). If you get into chip resistors, you need to go smaller.
For the small parts, you can bend “needle tips” slightly. You can buy packs of 50 from Digikey (search “Luer Lock”), but might find it cheaper to get individual ones from either medical supply places, or buying products which use them. For example some static-safe squeeze bottles come with a few tips. Again the expensive but easy route is Chip Quik part # SMDTA200 which has a bunch of different sized tips.
There is three main options for stencils:
Laser cut stainless steel.
Third-party cut Kapton film.
Self-cut Kapton/Mylar film.
For laser-cut stainless steel, this can typically be ordered with your PCB fab. For example 3PCB.com and Dirty PCBs offer them very cheaply (~$25) when ordering PCBs. This is almost always the best choice, as the stainless steel stencils are very reliable and I’ve had great success with BGA devices.
You can also use third-party services to cut Mylar or Kapton film for you. OSHStencils is one example of a supplier.
Finally, you can make your own. You’ll need some practice to cut BGA parts, but it’s quite easy to cut stencils for less demanding applications. I have a previous blog post on my method.
I’ve been making my own stencils with this process for some time with great success.
I generally just buy solder past from Digikey. Digikey does a great job of cheaply shipping to Canada, and the paste comes in an awesome cold pack thingy that keeps it cool during the trip. Chip Quik (again with the Chip Quik sorry, I don’t have a connection with them but just end up using their stuff!) sells some nice small syringes. Be aware it does have a shelf life… I’ve used past about 6-12 months paste that date, but you will eventually see issues (balling, flux separates). I recommend keeping to the suggested date to avoid giving yourself the headache of discovering your paste is bad after you’ve tried soldering your PCB. The cost of all your parts is probably a lot more expensive than the cost of replacing your paste.