Reported by Google Project Zero, the security researcher found a new iOS12 bug and vulnerability on iMessange, the issue relates to a specific type of malformed message that is sent out to a victim device. The bug was kept from the public to keep the devices safe but now after 90 days had pass apple fix the issue. Apple’s release a new ipsw update firmware iOS 12.3 fixing the bug and allowing for it to be revealed.
On a MacOS, this causes a crash and respawn, but on an iPhone, this code is in Springboard. Receiving this message will make Springboard to crash and respawn repeatedly, causing the UI not to be displayed and the phone to stop responding to input. This means a boot loop.
This condition survives a hard reset and causes the phone to be unusable as soon as it is unlocked. The only way to find to fix the iPhone is to reboot into recovery mode and do a clean restore. This causes the data on the device to be lost though.
How to fix bootloop imessage bug
This was fixed in the 12.3 update.
There are three ways that I found to unbrick the device:
- wipe the device using ‘Find my iPhone’ icloud.com page.
- Put the device in recovery mode and update via iTunes and update to the latest version.
- Remove the SIM card and go out of Wifi range and wipe the device from menu settings factory restore.