Replicating the bug is easy but not something the average user would ever do accidentally. Setting the system clock back to January 1st, 1970 and then rebooting the device as prompted leaves it dead and unusable. The iPhone or iPad will fail to start up after every subsequent boot.
Users who have attempted to restore or repair their phone using iTunes on their computer have failed to get the device working again. Although it is detected correctly by the software, iOS still refuses to load after the reset, 9to5Mac reports.
Only some recent devices are affected. The iPhone or iPad has to be running iOS 8 or newer and be based on a 64-bit processor. These include Apple’s A7, A8, A8X, A9 and A9X processors which have been used in its products since the launch of the iPhone 5s.
It is highly unlikely that a typical iPhone user would be able to accidentally brick their phone because of the bug. The date has to be manually changed, a process which involves repetitively scrolling back in time and then confirming a prompt.
As usual, Apple hasn’t commented on the cause. The issue appears to be related to time zones though with current speculation suggesting the date can cause the system clock to have a “negative” time, leaving the software unusable.
Programmers know January 1st, 1970 to be a special time as it represents the start of “Unix time.” This system was first used by Unix-based operating systems as the basis for their clock, setting January 1st, 1970 as the epoch and counting the seconds elapsed since. Unix time has stuck in computing and is now generally used as the start of time in software programs.
By setting the date to January 1st, 1970, iOS is led to believe it is at the start of time. Depending on the specified time zone, it is possible it then ends up calculating the current time as being before the Unix epoch, creating a negative value of time that is unusable by the software.
Further credence is added to this theory by unverified reports of “bricked” devices becoming usable again several hours after the date is set. 9to5Mac reports that one Twitter user could successfully boot their phone 5 hours after experiencing the bug, suggesting that as time moves forward the device’s clock sets itself to a value after the epoch and is able to boot up. This doesn’t seem to be the case for every user though.
Apple hasn’t provided any indication it is working on a fix but most people shouldn’t be affected by this bug and its severe effects. It could be used as a cruel prank amongst friends but is unlikely to start randomly propagating across iPhones, unless a hacker in a public place works out how to force iOS to change its date over a network.
