The digital touch iMessage extension can read out of bounds if a malformed Tap message contains a color array that is shorter than the points array and delta array. The method [ETTapMessage initWithArchiveData:] checks that the points array is twice as long as the deltas array, but only checks that the colors array is longer than eight bytes, even though a color is needed for every point-delta pair that is processed.
To reproduce the issue with the files in tapcrash.zip:
1) install frida (pip3 install frida)
2) open sendMessage.py, and replace the sample receiver with the phone number or email of the target device
3) in injectMessage.js replace the marker "FULL PATH" with the path of the obj file
4) in the local directory, run:
This will lead to a crash in SpringBoard requiring no user interaction.
I've also attached a crash dump and ETencode.m, which is the file that was used to generate the obj file.
Proof of Concept: