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Text ‘bomb’ crashes iPhones, iPads, Macs and Apple Watches – what you need to know

Text 'bomb' crashes iPhones, iPads, Macs and Apple Watches - what you need to know

An innocent-looking message, containing characters in the Sindhi language, can cause your
iPhone, iPad, Mac, or even Apple Watch to crash without warning.

The problem appears to exists in how the latest shipping versions of Apple’s operating system handle a Unicode symbol representing specific characters written in Sindhi, an official language in part of Pakistan.

The problem occurs most irritatingly when your device attempts to display a message notification. If you have configured your iPhone, for instance, to display a new message notification which includes a preview of the message, then iOS fails to properly render the characters and crashes with unpredictable results.

You may find the only way to get around the problem is to completely reboot your device – but there is always the risk that you will receive a new boobytrapped notification.

The problem can also manifest itself inside apps. For instance, some mischievous Twitter users have tweeted the offending characters causing other users to have their devices crash.

Android users, meanwhile, are unaffected – and can watch the chaos with bemusement.

Some of the earliest reports suggested that for the attack to work the Sindhi characters had to be used in conjunction with an Italian flag emoji. However, others have claimed that an Italian flag is not required to be in the message for devices to crash.

Clearly such a flaw is irritating, especially if you happen to find yourself receiving a barrage of text ‘bombs’.

If all this sounds like a familiar problem to you, that’s because Apple has had problems in the past with Unicode characters crashing its operating systems.

For instance, way back in 2013 it was found that Macs and iPhones could be crashed by a simple string of Arabic characters.

In 2015, an attack called “Effective Power” saw iPhones being remotely rebooted when pranksters sent a sequence of characters via iMessage.

And in 2018 we saw both Apple devices crash as they attempted to display letters from the south Indian language of Telugu, and the so-called chaiOS bug made it possible to crash iOS and macOS with a single text message.

The answer in all these cases has been for Apple to push out a fix to its operating systems to better handle the Unicode symbol.

And that’s what, I’m sure, will happen this time. According to those who have tested it, the latest beta version of iOS already incorporates a fix for the problem – so we may only be days away from having it pushed out to our vulnerable devices.

In the meantime, if you are worried or think you might be targeted by a mischief-maker who delights in crashing your device, you might be wise to disable message previews on your iPhone.

About the author

Graham CLULEY

Graham Cluley is an award-winning security blogger, researcher and public speaker. He has been working in the computer security industry since the early 1990s, having been employed by companies such as Sophos, McAfee and Dr Solomon's. He has given talks about computer security for some of the world's largest companies, worked with law enforcement agencies on investigations into hacking groups, and regularly appears on TV and radio explaining computer security threats.

Graham Cluley was inducted into the InfoSecurity Europe Hall of Fame in 2011, and was given an honorary mention in the "10 Greatest Britons in IT History" for his contribution as a leading authority in internet security.