Hacking the Silvercrest (Lidl) Smart Home Gateway
paulbanks.org
paulbanks.org
Excellent! This is the way security should be done if you have to use a password like here.
Too many devices either don't have brute force detection, or don't persist their intervals meaning a reboot gives you new attempts.
When a remote login fails on these devices, it kills its ssh server process, waits a certain amount of (time * how many failed attempts)ms, then starts it back up?
But if you truly hammer at one of these devices you could force it to reboot, which makes it forget the counter, so an attackers gets an unlimited number of the “cheapest” guesses (though it’d still slow it down a bit).
The solution is the machine physically writes the memory from RAM into onboard FLASH mem, and is reading/writing the count variable to a file instead of just using a variable.
FLASH memory is the type that keeps state as long as it has a trickle of power, so as long as the device is plugged in, this is essentially “long term” storage (but not truly like a hdd would be).
A reboot will wipe the systems RAM (because you don’t want any bad state from behaviour lurking around), but not the FLASH. And because it doesn’t ever physically cut the power the FLASH persists and the intended increasingly harsh punishment for failed logins works.
Lower level stuff is awesome.
Or is the point that the counter only counts time when the device is on? Kinda of like anacron vs cron
Former home automation software developer speaking here.
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I definitely dont like the look of it.. Black chips on a black background.. makes the board harder to 'read' at a glance imo.
Edit: Answered my own question.. https://www.quick-pcba.com/pcb-news/questions-about-black-pc...
It is simply fashion + this : Anti-plagiarism. Because the traces of black PCB are difficult to distinguish with the naked eye.
Also seems there are some disadvantages of not using green.
Kind of makes me nostalgic and want to build a high-end PC with only “retro” green PCB components
It won't slow down anyone seriously trying to copy your product, since they'll just depopulate the board and use "bed of nails" or "fly wire" scanning technology to recover the netlist automatically. It does frustrate repair attempts, however.
High-end server-oriented stuff still tends to be "boring" green.
25 euros at Lidl de
Here's some more data about the CPU and RF module used:
http://www.hytic.net/upload/files/2015/09/REALTEK-RTL8196E.p...
https://developer.tuya.com/en/docs/iot/zigbeetyzs4module?id=...
(last one needs login for full datasheet)
Considering it is basically an ethernet<=>Zigbee bridge, and never needs to send more than a few bytes at a time, I would have designed it with a Wifi ESP8266 connected to a zigbee module.
With that setup you could probably cut the retail price in half, which has to be important for a device nobody really wants (People get excited about their new smart bulbs... Nobody cares about the pesky gateway device)
I don't feel like the on-device code is the expensive bit of this.
Any user support (extreme example: dealing with user who brick their devices or play with it in unintended way) cuts into profit.