A researcher has recently disclosed a DoS bug in Apple HomeKit which he coined ‘doorLock.’ Exploiting this bug renders the HomeKit devices non-functional as it continues to trigger even after rebooting. This bug likely affects all iOS devices from iOS 14.7 to iOS 15.2. However, it has still not received a patch from Apple.
Apple HomeKit ‘doorLock’ DoS Flaw
Security researcher Trevor Spiniolas has shared a detailed post about a denial-of-service vulnerability affecting Apple users. Identified as ‘doorLock,’ this DoS bug affects many iPhones and iPads, thereby putting a considerable userbase at risk.
Briefly, the issue resides in how the operating system renders the name of an Apple HomeKit device. Setting up a long device name (such as a 500,000-character string that the researcher tested) will trigger a Dos state on the affected iOS device.
This vulnerability typically exists in iOS versions earlier than iOS 15 because Apple since introduced a character limit on the name. However, this bug also affects iOS 15 devices since it will occur if a vulnerable device shares HomeKit data with a non-vulnerable device.
What’s worse is that the bug doesn’t resolve with a reboot. Instead, it will keep triggering right after the user signs in to the iCloud account linked with the HomeKit device.
The researcher demonstrated the exploit in this video.
The following video shows how an adversary can trigger the bug via fake invitations. This exploit can even trick users with no HomeKit device.
Spiniolas has also shared an app on GitHub that triggers this bug. (Use it for testing purposes only).
Patch Still Awaited
After discovering the vulnerability, the researcher contacted Apple to report the matter in August 2021. Unfortunately, while the Cupertino giant acknowledged the bug, they didn’t exhibit promptness to address it.
According to the researcher, Apple kept delaying the fix, eventually promising it for “early 2022”. However, given the flaw’s seriousness upon exploitation, the researcher went for public disclosure to alert users. As stated in his post,
This bug poses a significant risk to the data of iOS users, but the public can protect themselves from the worst of its effects by disabling Home devices in control center in order to protect local data.
While a definitive solution to this denial-of-service bug is yet to arrive, the researcher recommends the affected users to recover their device via the DFU Mode, setting it up as normal without signing in to the iCloud account and then logging into the iCloud via Settings. Users can then choose to disable “Home” immediately to render the device and iCloud account function again.
Whereas, for those who still want to access Home Data, the researcher advises the following step after signing into their iCloud account via Settings.
-Press the back button and then press Control Center settings again to reload the page, and repeat this until a setting labeled “Show Home Controls” is visible. Immediately disable the setting.
-Install the test application and run it with a short string to rename all associated Home devices.
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