Hackers could remotely control the latest IoT-equipped Aga ovens by just sending a text message, according to security researchers.
The latest Aga ovens feature an IoT device called Total Control, which allows users to access the oven's functions through a mobile or web app. The device connects to the internet via a SIM card and a cellular radio connected to a mobile phone network. This enables Aga ovens to receive and send text messages from anywhere in the world.
But according to Ken Munro, partner at Pen Test Partners, hackers can quite easily operate the cooker without the owner's knowledge.
In a blog post, he said the mobile app passes messages onto an API, but the app communicates over plain text HTTP. He added that the Android app explicitly disables certificate validation through use of ALLOW_ALL_HOSTNAME_VERIFIER. "Even if it did offer SSL, it would thus be trivial for rogues to intercept and modify traffic," he said.
He found that the physical module connected to the oven contained a GSM SIM, which costs 6 per month to maintain mobile connectivity.
But the main issue was the web app that allowed plain text over HTTP, which said Munro, didn't protect customer data in transit. The app enumerates the SIM card phone number, mistype a number and an error will appear.
"Put in a valid number (i.e. +44 845 712 52 as suggested by the app when you make an invalid entry) and you'll see that it's already registered. It's not actually a valid phone number, so likely someone has been interfering with this website!" he said.
"So those with nefarious intentions could enumerate a list of all the valid Aga cooker phone numbers. Time consuming, but likely effective."
He added that the app's password policy is only five characters. "This is starting to get pretty irresponsible of Aga; customers will have their cookers compromised," said Munro.
Munro said the app also had no validation of the number and authentication of messages, meaning that hackers could simply send a text to a cooker and turn them off or on at will.
"One could also power up people's Agas when they're not looking, wasting electricity. They draw around 30 Amps in full heat-up mode, so if you could switch enough Agas on at once, one could cause power spikes," said Munro.
He added that the web interface lends itself to "spamming the hell out of people using SMS at Aga's expense".
Munro said that the disclosure process with Aga was a "train wreck".
"We tried Twitter, every email address we could find and then rang them up. No response to any of the messages we left."
He urged the firm to ditch the SMS based remote control module and put in a secure Wi-Fi enabled module with mobile app.
He also noted that the SIM module is made by Tekelek and this company has a history in remote monitoring of oil storage tanks, heating systems, process control and medical devices among many things.
"These appear to be monitored using SMS, so I wonder where else this bizarre unauthenticated text messaging process might lead," said Munro.
IT Pro has approached Aga for comment.
