A simple text will bring your iPhone to its knees [Update]
It does not take sophisticated software or advanced knowledge of iOS to cause an iPhone and its Messages app to crash, as a simple text message can do the job just fine. As an iPhone 6 Plus user, this is the first time that I am feeling vulnerable for using an Apple smartphone.
And I am not alone, as an increasing number of iPhone users are taking to Twitter to complain about this bug, which can be triggered with anyone who is also using an iPhone. The text that has to be sent contains a specific sequence, which triggers the crash.
I asked my colleague Wayne Williams, who is rocking an iPhone 5s, to help me identify where and when that text message triggers the bug. What I have found out is that the bug rears its ugly head while my iPhone 6 Plus is unlocked and showing the homescreen, at the lockscreen, and even locked, with the screen obviously turned off. My iPhone 6 Plus is running the latest version of iOS, 8.3.
When my iPhone 6 Plus is showing the Messages app receiving the message does not cause any crash. However, in the aforementioned scenarios, the device will show the Apple logo, like it is rebooting, and recover after a couple of seconds, at which point it goes straight to the lockscreen.
I have mentioned above that the bug surfaces in iPhone to iPhone communication; sending a message from a Samsung Galaxy S5 (and likely any other smartphone or phone) will not cause any crashes. This leads me to believe that iMessages is likely the culprit -- seeing as iPhone to iPhone communication is done straight through iMessages.
The exact moment when my iPhone 6 Plus crashes is most probably -- most probably because I cannot verify this with absolute accuracy -- the time when notifications have to be shown -- or are triggered -- on the screen. In the Messages app this is not necessary, so receiving that text message has not caused any problems there for me.
The crashes are noticeable when my iPhone 6 Plus is showing the homescreen or lockscreen. While it is locked, and the screen is off, it will not show the Apple logo, like it is going through the reboot sequence, but it will turn the screen on and show the lockscreen. This leads me to believe that it is going through the same sequence as before, only in the background. In this scenario, as opposed to the other two, the Messages app will not show an updated notification counter, to reflect the arrival of the new message.
Until Apple sorts this problem out, you can get around this bug or reduce your chances of encountering it by disabling iMessage or -- I have not tested this to be sure, so I cannot say whether it really helps -- enable the "Filter unknown senders" option under Messages, in Settings, respectively. 9to5Mac suggests that you can also send yourself a message using Siri, the share menu or from your Mac, to recover your iPhone, which might come in handy in case the outcome is even worse than I described.
We do not want to make it easier for iPhone users to crash other users' iPhones, so I will not include the problematic text message in this article. Of course, those of you who want to wreak a bit of havoc, will surely find it.
Update: After a couple more tries, it looks like the bug can also be triggered from other smartphones, not just iPhones. That said, it does not seem to always result in a crash when sending the message from those devices, which is likely why it did not work in my initial testing. That also means that iMessage is likely not the culprit as I initially suspected.