Source Link Privacy.
Tarlogic Security has detected a backdoor in the ESP32, a microcontroller that enables WiFi and Bluetooth connection and is present in millions of mass-market IoT devices. Exploitation of this backdoor would allow hostile actors to conduct impersonation attacks and permanently infect sensitive devices such as mobile phones, computers, smart locks or medical equipment by bypassing code audit controls.
Update: The ESP32 “backdoor” that wasn’t.
At this point I welcome them to come through.
Come through with what though?
welp, TL;DR from comments says its fear mongering at best, physical access required right?
Does anyone know where it is that we can find these new commands? I have an esp32 dev kit just a few feet away from me as i read this. It might be interesting to know what these new product “features” are.
This isn’t a backdoor. Just a company trying to make a name for themselves by sensationalizing a much smaller discovery.
Seriously this. Every single IC which has digital logic contains some number of undocumented test commands used to ensure it meets all the required specifications during production. They’re not intended to be used for normal operation and almost never included in datasheets.
If anyone’s ever followed console emulator development, they know those undocumented commands are everywhere. There’s still people finding new ones for the N64 hardware
Edit: I should say undocumented behavior, not necessarily new commands
The rebuttal wasn’t as comforting as some are making it out to be. They seem to be more interested in the semantics of it not being a backdoor tied to a specific product, which appears to be true.
Rather it is a potential for vulnerability that exists in all wireless implementation, which seems to me to be a bigger issue.
The issue is where the undocumented commands are. They aren’t just allowing any old external person to send payloads to this.
It’s kind of like noticing that someone unexpectedly hid a spare key next to the door… On the inside of the house. Like, sure, maybe the owner would have like to know about that key, but since you have to be inside the house to get to it, it doesn’t really make a difference.
It’s a vulnerability where an attacker already needs code execution on the device/physical access.
If you have that you’re already compromised no matter what.
I was reading someone else’s explanation and they said it’s the equivalent of every computer possibly having a backdoor because there is code in a computer that a bad actor can use. There are extra commands that could possibly be used for a backdoor if a malicious actor found a way to use those bits of code. It’s much less oh here is a security vulnerability that is being used and more of a if a robber breaks into our house which is possible they will rob us situation.
Please update the title of this post to mention the update
How so?
Idk maybe specify that it was determined to not be a backdoor. Right now it reads as anti-china fear mongering.
Thank you, I keep getting down voted because I said the same, but obviously other get it. Appreciate you and the sanity check!
Could be propaganda as well - why not scare the monkeys with the bad Chinese? Without ESPs the market is so much easier to control.
Note:I use both the ES8266ex and different ESP32s in my projects.
You can edit post titles as well as content (even images!) on Lemmy.
Weird that they removed the reference to ESP32, one of the most common and widely known microcontrollers, from the headline.
It’s because the security company basically lied about this being a vulnerability, and probably opened themselves up to a lawsuit.
Gotta blame China to get upvoted on Lemmy.
Yeah, one of those is factually correct and got upvoted…
You’re kidding, right?
Or use a precise title. It’s not a backdoor or a “backdoor”.
This sounds like there are some undocumented opcodes on the HCI side – the Host Computer Interface – not the wireless side. By itself, it’s not that big a deal. If someone can prove that there’s some sort of custom BLE packet that gives access to those HCI opcodes wirelessly, I’d be REALLY concerned.
But if it’s just on the host side, you can only get to it if you’ve cracked the box and have access to the wiring. If someone has that kind of access, they’re likely to be able to flash their own firmware and take over the whole device anyway.
Not sure this disclosure increases the risk any. I wouldn’t start panicking.
So explained to me, a tech illiterate in comparison, this is China bad scaremongering?
‘Backdoor’ sounds malicious with intent.Pull up a chair and pour yourself a stiff beverage…
TLDR: Don’t Panic.
If you have a regular old processor (MCU) and want to give it wireless capability, you can buy a wireless chip and stick it next to the processor, then have the MCU talk to it through a wired connection (typically UART or SPI). Think of it as the old ATDT commands that had your PC control your old screeching modems.
To standardize this communication protocol, folks came up with the Host Controller Interface (HCI) so you didn’t have to reinvent that protocol for every new chip. This was handy for people on the MCU side, since they could write firmware that worked with any wireless chip out there, and could swap out for a cheaper/faster one with minimal change.
Fast forward to the era of integrated MCU+wireless, where you had a little ARM or other lightweight processor plus a little radio, and the processor could run programs in a high-level API that abstracted out the low level wireless stuff. Plus, you could use the same radio for multiple wireless protocols, like BLE, wifi, ANT, etc. Nordic and TI were early adopters of this method.
Typically, it was the vendor’s own processor talking to their own wireless module, but they still implemented the full HCI interface and let it be accessed externally. Why? So if your design needed an extra beefy processor and used the MCU+wireless chip as a simple communication module, this would still work. The teeny MCU could be used to run something extra in parallel, or it could just sit idle. A typical example could be a laptop or cell phone. The little MCU is too small for everything else, so you pair it with a big chip and the big chip drives the little chip through HCI.
Sure, it would be cheaper if you just went with a basic ‘dumb’ wireless chip, as folks from CSR, Broadcom, and Dialog kept pointing out. But the market demanded integrated chips so we could have $10 activity trackers, fancy overpriced lightbulbs, and Twerking Santas (https://www.amazon.com/twerking-santa-claus/s?k=twerking+santa+claus).
For integrated MCU+wireless chips, most vendors didn’t release the super low-level firmware that ran between them. There was no need. It was internal plumbing. They exposed SDKs so you could control the wireless chip, or high-level Bluetooth/wifi APIs so you could connect and talk to the outside world in a few lines of code. These SDKs were unique to each vendor (like Nordic’s nRF Connect library, or TI’s SimpleLink SDK).
Then along came Espressif out of Shanghai, China with a combo chip (ESP8266) that offered processor + wifi and was so cheap and easy to program that it took the hobbyist market by storm. Oh, god… so many LED light strips, perfect for Christmas and blinky EDM lightup outfits (hello, Adafruit: https://www.adafruit.com/category/65).
Fast forward and Espressif drops the ESP32. A bigger, faster Tensilica Xtensa processor, with built-in flash storage, plus wifi, Bluetooth, and BLE in one place. Plus lots of peripherals, busses, and IO pins. Also, running FreeRTOS and eventually Arduino SDKs, and MicroPython. All for less than $5! It took off like a rocket. So many products. Plus, you could run them as little webservers. Who doesn’l love a little webserver in their pocket?
It’s gone through a few variations, including swapping out the Tensilica with an open-source RISC-V MCU, but otherwise it’s a massive seller and the gateway drug for most IoT/Smarthome nerds.
So along come these Tarlogic researchers, looking to build a direct USB to bluetooth library. This way, you can drive the wireless from, say Linux, directly. There are already BLE to USB stacks, but this one is giving access at the HCI level, in a C library. Handy if you’re doing research or developing drivers, but not the sort of thing your typical DIY person needs.
As part of their process, the researchers decide to dump the really low level ESP32 firmware and reverse engineer it.
A typical HCI implementation is a giant event loop that handles HCI opcodes and parameters. Host wants to talk to the outside world, it sets up some registers, configures the unique MAC address, then opens a channel and starts sending/receiving (hopefully without the modem screeching tones). There are typical packet encoders and decoders, multiple ISO/TCP layers, and the sort of thing that most people assume somebody else has gotten right.
For fancier implementations, there may be interrupt or DMA support. Sometimes, there’s a multi-tasking part under the hood so they can time-slice between wifi, bluetooth, and ble (aka Fusion or Coexistence support). Not that you should care. The internals of this stuff is usually nobody’s business and the vendors just include a binary blob as part of their SDK that handles things. The host systems just talk HCI. The wireless side talks HCI on the wired side, and wireless on the radio side. Everyone’s happy.
In the process of reverse engineering the low-level HCI blob, these researchers found a few extra undocumented HCI opcodes. They’re not sure what they’re for, but according to their presentation (https://www.documentcloud.org/documents/25554812-2025-rootedcon-bluetoothtools/) if my super rusty Spanish holds up, it has to do with setting MAC addresses and handling low-level Link-Level Control Protocol communications (https://www.ellisys.com/technology/een_bt10.pdf).
Now in an of itself, this is no big deal. ESP32s already let you easily set your own temporary MAC address (https://randomnerdtutorials.com/get-change-esp32-esp8266-mac-address-arduino/), so there has to be a way to override the manufacturer one. And LLCP management is a totally geeky low-level thing that the MCU needs when handling wireless packets. There are perfectly good reasons why the opcodes would be there and why Espressif may not have documented them (for example, they could be used only during manufacturing QA).
So the original presentation is a teeny bit of an exaggeration. Yes, the opcodes exists. But are they nefarious? Should we stick all our ESP32s inside Faraday cages? Is this a secret plan for the CCP to remotely control our lights and plunge the world into chaos?
As I said before, ONLY if there’s a secret as-yet-undiscovered wireless handshake that gives remote wireless access to these (or really, pretty much any other published HCI opcode). That presentation most definitely doesn’t claim that.
To see if there is a REAL backdoor, you should wait for an analysis from fine professional wireless debugging vendors like Ellisys (starting models run $30K and up), Frontline, or Spanalytics.
Incidentally, Tarlogic, the group that put out that paper have their own BLE analyzer product (https://www.tarlogic.com/es/productos/analizador-bluetooth-le/). They look to know their stuff, so they should know better than putting out clickbait-y hair-on-fire reports. But come on, who can resist a good CCP/backdoor headline? Will media run with this and blow it out of proportion? No way!
If you’ve read this far, you must safely be on your third drink or the edible’s just kicked in. Stop panicking, and wait until the pro sniffer and Bluetooth forum people give their opinions.
If it turns out there is an actual WIRELESS backdoor, then by all means, feel free to panic and toss out all your Smarthome plugs. Go ahead and revert to getting up and flicking on your light switch like a peasant. Have a sad, twerk-free Christmas.
But over a few undocumented HCI opcodes? Have another drink and relax.
Happy Sunday.
PS: controversy already up on wikipedia: https://en.m.wikipedia.org/wiki/ESP32
PPS: you may want to stock up on ESP32s for your light-up Christmas light project. Don’t be surprised if Espressif gets smacked with some hard tariffs or an outright ban, based on these ragebait headlines 🤷🏻♂️
Edit: DarkMentor offers a little more detail on the nature of the opcodes: https://darkmentor.com/blog/esp32_non-backdoor/
what a fantastic write up. thank you so much for taking the time <3
This is a very good comment. I’d give you Lemmy Gold if such a thing existed. Thanks for posting it!
The article is a security company trying to hype their company with a theoretical attack that currently has no hypothetical way to be abused
The article has an update now fixing the wording to “hidden feature” but, spoilers, every BT device has vendor specific commands.
The documentation of the part just wasn’t complete and this companies “fuzzing” tool found some vendor commands that weren’t in the data sheet
The China part just came from OP
The article is a security company
trying to hype their companyruining their reputation in an incredibly ill-thought out attack that companies will ABSOLUTELY remember.Even worse, it just makes this security company look incompetent. Like a home security company that announces a huge vulnerability in Schlage locks- there’s a key that can unlock the lock included with every lock sold!!11!!!11!one!
I agree, but unfortunately, this has become common since Heartbleed, and they seem to be able to sell their snake oil to CTOs…
thank you
Fukin dmnit! I just spent the last several months fine tuning a PCB design supporting this platform. I have , what i believe to be my last iteration, being sent to fab now. I have to look i to this. My solution isnt using bluetooth, so i dont know if im vulnerable.
Go for it. It’s a bullshit attention grab. No backdoor, just some undocumented vendor commands (which is the norm for virtually every chip out there).
The exploit requires physical access. It’s not exploitable in 99% of cases
Its not a backdoor, you’re most likely fine.
I hate it when an attacker who already has root access to my device gets sightly more access to the firmware. Definitely spin up a website and a logo, maybe a post in Bloomberg.
Haha. I wear cheap Chinese bluetooth literally on my skull like 95% of the time, web when sleeping.
Hope they enjoy my thoughts.
We really should be pushing for fully open source stack (firmware, os) in all iot devices. They are not very complicated so this should be entirely possible. Probably will need a EU law though.
Open source stack will not prevent this. It’s not even a backdoor, it’s functionality that these researches think should be hidden from programmers for whatever reason.
Open source devices would have this functionality readily available for programmers. Look at rtl-sdr, using the words of these researches, it has a “backdoor” where a TV dongle may be used to listen to garage key fobs gasp everyone panic now!
thats a very fair point, I had not seen anyone else make this one But the problem is that in this case, this functionality was entirely undocumented. I dont think it was intended for programmers.
Now if the firmware was open source, people would have gotten to know about this much sooner even if not documented. Also such functionality should ideally be gated somehow through some auth mechanism.
Also just like how the linux kernel allows decades old devices to be at the very least patched for security risks, open firmware would allow users of this chip to patch it themselves for bugs, security issues.
Yeah, of course, it would be better in many ways if the firmware wasn’t closed.
I 100% believe firmware should be open source no question about it. There’s so many devices out there especially phones and iot devices that just become e-waste because you can’t do anything with it once it’s not supported if it was open source and documented in some way then it could be used. I have like five cheap phones that I got because they were so cheap but once they lost support they’ve become completely useless even though they still work.
But then big companies wouldn’t be able to keep milking the consumer via planned obsolescence. Won’t somebody think of the shareholders?
This is about silicon. Undocumented instructions have just been found in it but they are not executable unless the ESP32’s firmware uses them. Firmware cannot be edited to use them unless you have an existing vulnerability such as physical access or insecure OTA in existing firmware (as far as researchers know).
Backdoored devices are useful for people who can impede that.
And the way EU is approaching privacy, surveillance and all such, - oh-hoh-ho, I don’t think there will be a EU law.
Yeah tons of weird little private softwares never get updates, but they aren’t making anyone money either
Well… Shit.
There are so, so, so, many ESP32’s in not just my house, but practically everyone I know.
There outta be fines for this BS.
You’re fine. This isn’t something that can be exploited over wifi. You literally need physical access to the device to exploit it as it’s commands over USB that allow flashing the chip.
This is a security firm making everything sound scary because they want you to buy their testing device.
You literally need physical access to the device to exploit it
You don’t need physical access. Read the article. The researcher used physical USB to discover that the Bluetooth firmware has backdoors. It doesn’t require physical access to exploit.
It’s Bluetooth that’s vulnerable.
I just re-read the article and yes, you still need physical access.
The exploit is one that bypasses OS protections to writing to the firmware. In otherwords, you need to get the device to run a malicious piece of code or exploit a vulnerability in already running code that also interacts with the bluetooth stack.
The exploit, explicitly, is not one that can be carried out with a drive-by Bluetooth connection. You also need faulty software running on the device.
“Depending on how Bluetooth stacks handle HCI commands on the device, remote exploitation of the backdoor might be possible via malicious firmware or rogue Bluetooth connections.”
I of course don’t know details but I’m basing my post on that sentence. “Backdoor may be possible via … rogue Bluetooth connections.”
Looking at the article, the exploit requires you to be able to send arbitrary data to the Bluetooth device over a physical connection. This means that a properly secure application will be protected from drive by connections, but if the application has an exploit that either lets an attacker write arbitrary values to the Bluetooth controller, or more likely contains a general arbitrary code execution exploit, then you could use this to rewrite values to the chip that would let you “persist” certain changes to the Bluetooth chip that would be difficult to notice.
I would consider this a moderate concern, as this will definitely increase your options if you’re looking to be able to make an attack that targets a specific device and this gives you a few additional persistence options, but any attack would have to be designed for a particular program running connected to a Bluetooth chip.
A more likely concern in my opinion would be the possibility of a supply chain attack, where someone compromises a Bluetooth chip that they know will be used to construct a particular part.
I don’t think that it’s super likely that either of these will affect the average person, only corporations and governments where espionage is an actual threat, as if you can find a Bluetooth IOT device that you want to mess with, like a Bluetooth enabled door lock, then you’re more likely to be able to find an arbitrary code execution attack which causes it to unlock immediately. Being able to spoof a different Bluetooth device isn’t likely to give you that big of an advantage when you’re working with a device that was already vulnerable for a different reason.
thank you for the nice analysis. this should really be voted highest.
Thank you for the analysis, very insightful!
Do you reckon this is more of an oversight or bug in the BT stack, or a deliberately places backdoor as the title seems to suggest?
From what I can tell from looking at it, this seems like something deliberately left in, but not for malicious reasons. The op codes referenced simply give access to lower level parts of the boards programming. ESP32’s are already a user programmable board, a valid use case is to run your entire application on one if the code being run is lightweight enough to not interfere with the Bluetooth code. Either during development, or during runtime, these undocumented codes are likely used to run specific commands on the board.
The actual issue as far as I can tell, since normally it’s valid usage to rewrite the board over USB, is that ESP32 boards also offer ways to encrypt device code, and require it to be signed, and you are presumably able to mess with this in order to dump code that was expected to be securely encrypted, and overwrite code on devices that was intended to require signing. (https://docs.espressif.com/projects/esp-idf/en/latest/esp32s3/security/secure-boot-v2.html#background)
Proving what someone was thinking when they programmed something is extremely difficult unless you can find written evidence of someone specifically saying if they did something or not, but this all seems like a legitimate minor exploit in a device that wasn’t built by, or intended for, people who are working against highly resourced attackers. This is still not a concern for normal people who aren’t concerned about being attacked by spies, and if a nation state wanted to hide a vulnerability in something then there are far easier paths to take than one that only works if you can steal a microcontroller so you can connect to it over USB.
Depending on how Bluetooth stacks handle HCI commands on the device, remote exploitation of the backdoor might be possible via malicious firmware or rogue Bluetooth connections.
I really wish these articles just tell us what these scenarios are. I understand companies need publicity or need to sell software but if it isn’t replicatable and the article says “might be possible” it kind of sounds like a secuity sales pitch.
This is especially the case if an attacker already has root access, planted malware, or pushed a malicious update on the device that opens up low-level access.
This part basically sounds more like a software issue where the attacker has a way in already. The system is already vulernable at this point before using the exploit found.
I don’t think there’s enough information out yet.
It is very interesting though.
This is about silicon. Undocumented instructions have just been found in it but they are not executable unless the ESP32’s firmware uses them. Firmware cannot be edited to use them unless you have an existing vulnerability such as physical access or insecure OTA in existing firmware (as far as researchers know).
I do have a few outside. Probably not the best security-wise. Haha. Those are the first to get patched when one comes out.
Security wise, unless you are being specifically targeted by someone, you are almost certainly fine. And if you are being specifically targeted, I think someone hacking your ESPs is the least of your worries. A malicious attacker that knows your physical location can do a lot more scary things than just spying through ESPs.
Just wait until a jester creates a software that sends an erase flash backdoor command to any BT device it sees.
One of my friends is a type I diabetic. He had some sort of smart thingamajig in his teenage years for measuring blood sugar, so you could monitor it over time or warn your family if you’re in some critical situation.
The jester may mean simply to prank, but they may well have blood on their hands if they fuck up medical devices such as that one.
And runs with an USB cable flashing other peoples ESPs to ruin everyone’s day
In that case, how long til some open source project uses it to make a custom firmware to bypass the manufacturer bs and integrate my cheap IoTs seamlessly into Home assistant?
You can already reflash a lot of devices for this purpose. And you could use esp-home to customise once reflashed
Really? Where can I find this
Heres the top google link i found: https://randomnerdtutorials.com/how-to-flash-a-custom-firmware-to-sonoff/
Esp-home is available as a HA addin, docs here: https://esphome.io/
Thanks
Esp-home also works with the older esp-01 - it was released as a wifi module so there are only two gpio’s, but thats enough for a lot of home automation stuff.
Here’s one i have connected to HA, where HA uses rest-api to capture some data from a game called tacticus, and it shows my available tokens for guild raid and arena
Tasmota is another option if they have your specific device in their list. Otherwise you have to do some debugging to figure out what gpio or i2c address to use.
I think we are basically already there with ESPs :D.
Wrong. Read the analysis. It is a BT vulnerability. One can probably design a cheap attack system that just sends a erase flash command to any BT device in reach, instantly bricking every BT enabled ESP32 device.
Just reread it and no, it’s not a BT vulnerability. The “erase flash” command is something that has to be done by software running outside the BT stack. You can even see that inside the slides. The
UsbBluetoothsoftware is connected to the device with the flawed bluetooth chipset.The vulnerability is that if you have this chipset and compromised software, someone can flash the chipset with compromised flash. They even say that it’s not an easy attack to pull off in the article.
In general, though, physical access to the device’s USB or UART interface would be far riskier and a more realistic attack scenario.
In otherwords, the attack is something that can only be pulled off if there’s also a security vulnerability within other parts of the hardware stack.
Yeah, that’s not the main concern.
Too much fanfare and too little real info shared to be of any value. Sounds more like an ad than infosec
Exactly what it is. A gross example of company trying to get their name out their by sensationalizing their findings.
Seriously wtf did I just try to read? It sounded like AI slop.
