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23 Feb 2014: Hacking a Wifi Kettle

Here is a quick writeup of the protocol for the iKettle taken from my Google+ post earlier this month. This protocol allows you to write your own software to control your iKettle or get notifications from it, so you can integrate it into your desktop or existing home automation system.

The iKettle is advertised as the first wifi kettle, available in UK since February 2014. I bought mine on pre-order back in October 2013. When you first turn on the kettle it acts as a wifi hotspot and they supply an app for Android and iPhone that reconfigures the kettle to then connect to your local wifi hotspot instead. The app then communicates with the kettle on your local network enabling you to turn it on, set some temperature options, and get notification when it has boiled.

Once connected to your local network the device responds to ping requests and listens on two tcp ports, 23 and 2000. The wifi connectivity is enabled by a third party serial to wifi interface board and it responds similar to a HLK-WIFI-M03. Port 23 is used to configure the wifi board itself (to tell it what network to connect to and so on). Port 2000 is passed through to the processor in the iKettle to handle the main interface to the kettle.

Port 2000, main kettle interface

The iKettle wifi interface listens on tcp port 2000; all devices that connect to port 2000 share the same interface and therefore receive the same messages. The specification for the wifi serial board state that the device can only handle a few connections to this port at a time. The iKettle app also uses this port to do the initial discovery of the kettle on your network.

Discovery

Sending the string "HELLOKETTLE\n" to port 2000 will return with "HELLOAPP\n". You can use this to check you are talking to a kettle (and if the kettle has moved addresses due to dhcp you could scan the entire local network looking for devices that respond in this way. You might receive other HELLOAPP commands at later points as other apps on the network connect to the kettle.

Initial Status

Once connected you need to figure out if the kettle is currently doing anything as you will have missed any previous status messages. To do this you send the string "get sys status\n". The kettle will respond with the string "sys status key=\n" or "sys status key=X\n" where X is a single character. bitfields in character X tell you what buttons are currently active:

Bit 6	Bit 5	Bit 4	Bit 3	Bit 2	Bit 1
100C	95C	80C	65C	Warm	On

So, for example if you receive "sys status key=!" then buttons "100C" and "On" are currently active (and the kettle is therefore turned on and heating up to 100C).

Status messages

As the state of the kettle changes, either by someone pushing the physical button on the unit, using an app, or sending the command directly you will get async status messages. Note that although the status messages start with "0x" they are not really hex. Here are all the messages you could see:

sys status 0x100	100C selected
sys status 0x95	95C selected
sys status 0x80	80C selected
sys status 0x100	65C selected
sys status 0x11	Warm selected
sys status 0x10	Warm has ended
sys status 0x5	Turned on
sys status 0x0	Turned off
sys status 0x8005	Warm length is 5 minutes
sys status 0x8010	Warm length is 10 minutes
sys status 0x8020	Warm length is 20 minutes
sys status 0x3	Reached temperature
sys status 0x2	Problem (boiled dry?)
sys status 0x1	Kettle was removed (whilst on)

You can receive multiple status messages given one action, for example if you turn the kettle on you should get a "sys status 0x5" and a "sys status 0x100" showing the "on" and "100C" buttons are selected. When the kettle boils and turns off you'd get a "sys status 0x3" to notify you it boiled, followed by a "sys status 0x0" to indicate all the buttons are now off.

Sending an action

To send an action to the kettle you send one or more action messages corresponding to the physical keys on the unit. After sending an action you'll get status messages to confirm them.

set sys output 0x80	Select 100C button
set sys output 0x2	Select 95C button
set sys output 0x4000	Select 80C button
set sys output 0x200	Select 65C button
set sys output 0x8	Select Warm button
set sys output 0x8005	Warm option is 5 mins
set sys output 0x8010	Warm option is 10 mins
set sys output 0x8020	Warm option is 20 mins
set sys output 0x4	Select On button
set sys output 0x0	Turn off

Port 23, wifi interface

The user manual for this document is available online, so no need to repeat the document here. The iKettle uses the device with the default password of "000000" and disables the web interface.

If you're interested in looking at the web interface you can enable it by connecting to port 23 using telnet or nc, entering the password, then issuing the commands "AT+WEBS=1\n" then "AT+PMTF\n" then "AT+Z\n" and then you can open up a webserver on port 80 of the kettle and change or review the settings. I would not recommend you mess around with this interface, you could easily break the iKettle in a way that you can't easily fix. The interface gives you the option of uploading new firmware, but if you do this you could get into a state where the kettle processor can't correctly configure the interface and you're left with a broken kettle. Also the firmware is just for the wifi serial interface, not for the kettle control (the port 2000 stuff above), so there probably isn't much point.

Missing functions

The kettle processor knows the temperature but it doesn't expose that in any status message. I did try brute forcing the port 2000 interface using combinations of words in the dictionary, but I found no hidden features (and the folks behind the kettle confirmed there is no temperature read out). This is a shame since you could combine the temperature reading with time and figure out how full the kettle is whilst it is heating up. Hopefully they'll address this in a future revision.

Security Implications

The iKettle is designed to be contacted only through the local network - you don't want to be port forwarding to it through your firewall for example because the wifi serial interface is easily crashed by too many connections or bad packets. If you have access to a local network on which there is an iKettle you can certainly cause mischief by boiling the kettle, resetting it to factory settings, and probably even bricking it forever. However the cleverly designed segmentation between the kettle control and wifi interface means it's pretty unlikely you can do something more serious like overiding safety (i.e. keeping the kettle element on until something physically breaks).

Created: 23 Feb 2014
Tagged as: electronics, ha, security