Tripping on a Cracked Sidewalk

Sun, May 30, 2021 2-minute read

Amazon Sidewalk is a new project which allows Amazon devices (like Alexa, Ring doorbells, etc.) with different owners to share their Internet connections. In short, your Alexa talks to your neighbor's Alexa. If your Internet connection goes down, your neighbor's device will relay messages for your device so that it can keep working. Similarly, if your Ring doorbell is closer to your neighbor's Alexa than to your own WiFi router, it can send alerts to you through their Alexa.

This is a terrible idea.

This means that a device on your home network — a device you bought and paid for yourself — is letting other devices you don't control borrow your Internet connection. Amazon claims to have designed this as a secure system, but people in infosec know that a new security protocol written and implemented by a single company is going to be a mess. When (not if, but when) an attacker finds a flaw in the Sidewalk protocol or the devices it runs on, 2 terrible scenarios seem likely to happen:

  • However good and strong your WiFi password is, if an attacker can access your neighbor's network, they can hack your neighbor's Alexa and then use it to gain access to your own wireless network.
  • A braver attacker could sit outside your house with a hacked Alexa, or an app on their laptop that acts like one, and use it to connect to your Ring doorbell and then attack the other computers on your network.

If you have any Amazon devices, I strongly recommend you follow their instructions to turn off Sidewalk immediately. Because Amazon plans to turn this on for everyone who hasn't explicitly asked them not to, if you don't follow those instructions, you'll be allowing people near your home to use your WiFi. Some owners have claimed that they turned off Sidewalk but that it turned itself back on after a software update. If this happens in my home, I will literally throw our Alexas out in the trash.

Amazon Sidewalk is a solution without a problem. Turn it off. This is a potential disaster in the making.