Security researchers have discovered a glaring security hole that exposes the home network password of users of a Wi-Fi-enabled video doorbell. The issue – now resolved – underlines how default configurations of IoT components can introduce easy to exploit security holes.

The Ring allows punters to answer people knocking on your door from your mobile phone, even when you’re not at home. The kit acts as a CCTV camera, automatically activating if people approach your door, letting homeowners talk to visitors, delivery couriers and so on.

There’s an optional feature that allows the kit to hook up to some smart door locks, so users can let guests into their home even when they aren’t in. El Reg's review of the $200 device can be found here.

Security researchers at UK consultancy Pen Test Partners were impressed by this functionality but shocked when they carried out a security evaluation of the device.

The major component is the doorbell itself, which comes with electronics and battery and is fitted outside the house. The electronics are connected to a back plate which attaches the doorbell to the wall and can provide power from an AC source.

The device is secured outside a house using two commonly available Torx T4 screws, leaving it vulnerable to theft. Ring offer a free replacement if the kit is stolen, so homeowners are covered in that scenario (at least).

However that’s not the end of the problems with the device. An easy attack makes it all too simple to steal a homeowner's Wi-Fi key. To do this, hackers would need to take the kit off the door mounting, flip it over and press the orange "set up" button.

“Pressing the setup button [puts] the doorbell’s wireless module (a Gainspan wireless unit) into a setup mode, in which it acts as a Wi-Fi access point,” Pen Test Partners consultant David Lodge explains in a blog post.

The doorbell bundles a similar module to the Fitbit Aria bathroom scales and is subject to much the same wireless module-related vulnerability.

“By connecting to a web server running on the Gainspan unit, the wireless configuration is returned including the configured SSID and PSK in cleartext,” Lodge explained.

Something similar happens with the bathroom scales. The massive difference between the Fitbit Aria bug and this particular bug is that the doorbell is outside of the house, making potential attacks far easier.

Lodge writes: “The doorbell is only secured to its back plate by two standard screws. This means that it is possible for an attacker to gain access to the homeowner’s wireless network by unscrewing the Ring, pressing the setup button and accessing the configuration URL.”

The configuration URL is simple, so the attack could be pulled off using only a mobile device and a screwdriver. The device could be screwed back on afterwards, all without leaving any visible signs of tampering, Lodge warns.

“This is quite a fail: walk up to door, remove doorbell, retrieve user's Wi-Fi key, own their network,” he concludes.

The Ring told El Reg that the issue had been resolved via a firmware update released months ago, but apparently not present on the kit tested by Pen Test Partners.

This security vulnerability was remedied with Ring's firmware update 1.5 on August 11, 2015. Ring is now on firmware version 1.6. Every time Ring is activated, whether with motion or a doorbell ring, it automatically searches for available firmware updates. If users are concerned that their firmware may not be up-to-date, they can trigger the Ring; once the call ends, the button will flash white if there is an update. Once it's done flashing, the firmware is updated.

Pen Test Partners bought the doorbell from Amazon in early December. “Even if we were working on old firmware, the issue still stands,” Pen Test Partners Ken Munro told El Reg. ®