Security research firm Rhino Security Labs found a vulnerability in the Amazon Key in-home delivery service's security procedures that could allow either the courier or even a savvy and malicious bystander to enter your home undetected after the delivery is completed. Amazon has promised to change how Key works in order to make it easier for you to tell when something unusual is happening in this event, but the changes proposed by Amazon don't necessarily resolve the vulnerability.

Amazon Key is available to Amazon customers who have bought and installed Amazon's own Cloud Cam security camera and installed it at their front door. If you're one of those customers, you can select "in-home delivery" as a delivery method when purchasing something on Amazon. Amazon couriers can then authenticate themselves with your Cloud Cam to unlock the door and enter your home to leave the package. However, they can only do this at a home to which they're assigned to make a delivery and only at the scheduled time. They are recorded by your security camera as they make the delivery, and they must lock the door when they leave. Amazon also tracks which courier is assigned to the delivery, and only that courier has access.

Rhino Labs discovered that a courier equipped with a simple program can use their laptop to fake a command from your Wi-Fi router to disconnect the Cloud Cam from your network. This causes the camera to stop functioning by freezing the image at the last frame. At that point, the courier could re-enter your home, do whatever it is that they want there, and then exit, reactivate the camera, and lock the door as usual. This re-entry would be undetectable by the resident, and it would appear like a normal delivery in Amazon's data.

In theory, a bystander could also do this as a courier is leaving, but this is less likely for a few reasons. First, the bystander would have to know that delivery was scheduled and that it was to be an in-home delivery. Second, they'd have to do it before the courier locked the door, but the hack prevents the door from locking, and the courier is instructed not to leave until they've locked up.

Amazon’s response

Camera functionality is a critical part of Amazon's security pitch for Key. The company issued the following statement in response to reports about this issue:

We currently notify customers if the camera is offline for an extended period... Later this week, we will deploy an update to more quickly provide notifications if the camera goes offline during delivery.

This could help Amazon Key customers know when something is amiss, but it doesn't prevent the event from happening to begin with. Of course, the Amazon courier would likely be the prime suspect if a robbery or other crime was discovered, but small thefts might not be noticed soon enough to correlate them with the delivery.

Customers and lawyers had already raised concerns about using Amazon Key before Rhino Labs discovered this camera flaw. Rhino Labs founder Ben Caudill told Wired that fully fixing the loophole would need to involve caching video locally even if the camera is disconnected from the network. The Cloud Cam doesn't currently cache video locally.