A security research called Trevor Spiniolas has just published information about a bug he claims has existed in Apple’s iOS operating system since at least version 14.7.

The bug affects the Home app, Apple’s home automation software that lets you control home devices – webcams, doorbells, thermostats, light bulbs, and so on – that support Apple’s HomeKit ecosystem.

Spiniolas has dubbed the bug doorLock, giving it both a logo and a dedicated web page, claiming that although he disclosed it to Apple back in August 2021, the company’s attempts to patch it so far have been incomplete, and his specified deadline of 01 January 2022 for “going live” with details of the flaw has now passed:

I believe this bug is being handled inappropriately as it poses a serious risk to users and many months have passed without a comprehensive fix. The public should be aware of this vulnerability and how to prevent it from being exploited, rather than being kept in the dark.

You’ll have to make your own mind up about whether this bug truly “poses a serious risk”, but in this article we’ll tell you how to deal with the issue anyway.

The good news is that the bug doesn’t let attackers spy on your phone (or your HomeKit devices), steal data such as passwords or personal messages, install malware, rack up fraudulent online charges, or mess with your network.

Also, there are some easy ways to avoid getting bitten by this bug in the first place while you wait for Apple to come up with a complete fix.

The bad news is that if an attacker does trick you into triggering the bug, you could end up with a phone that’s so unresponsive that you have to do a firmware reset to get back into the device.

And, as you probably already knew – or, if you didn’t, you know now! – using Device Recovery or DFU (a direct firmware update, where you completely reinitialise the firmware of a recalcitrant iDevice over a USB cable) automatically wipes out all your personal data first.

Wiping your data when reinitialising the device is a feature, not a bug: it stops thieves simply grabbing your phone, doing a hard reset and a DFU of their own, and then reading off the old data from the device they’ve just ‘recovered’. Wiping your data is quick and reliable because Apple mobile devices always encrypt your data, even if you don’t set a lock code of your own, using a randomly chosen passphrase kept in secure storage. Wiping just this passphrase from the device is therefore enough to render all your data useless in one go, without having to wait for a overwrite of all the flash storage in the device, and without the uncertainty of whether any unencrypted data got left behind.