Researchers at Pen Test Partners took up the challenge to hack a smart fridge at Defcon's IoT Village, and discovered that they could man-in-the-middle your Google login credentials from Samsung fridges.
The fridges use your Google login to display your calendar. They incorrectly implement SSL: when presented with an incorrect certificate, they fail to validate it. This lets someone on your network — say, someone who's broken your wifi password — to get your Google login. With more work, the researchers believe they could overwrite the fridge's firmware and the mobile app that lets you control it.
Whilst the fridge implements SSL, it FAILS to validate SSL certificates, thereby enabling man-in-the-middle attacks against most connections. This includes those made to Google's servers to download Gmail calendar information for the on-screen display.
So, MITM the victim's fridge from next door, or on the road outside and you can potentially steal their Google credentials.
The notable exception to the rule above is when the terminal connects to the update server – we were able to isolate the URL https://www.samsungotn.net which is the same used by TVs, etc. We generated a set of certificates with the exact same contents as those on the real website (fake server cert + fake CA signing cert) in the hope that the validation was weak but it failed.
The terminal must have a copy of the CA and is making sure that the server's cert is signed against that one. We can't hack this without access to the file system where we could replace the CA it is validating against. Long story short we couldn't intercept communications between the fridge terminal and the update server.