A Crash You Can Type

Vincent Desmurs, a French iOS developer with the right kind of idle curiosity, found a combination of four characters that would instantly crash any iPhone running the then-current iOS. White flag emoji. Zero. Rainbow flag emoji. One invisible Unicode character your keyboard will never show you. Send that string to someone and their phone locks up cold.

The mechanism is almost charming in its stupidity: iOS attempts to fuse the white flag and the rainbow emoji into a rainbow flag, gets confused by the zero sitting between them, fails to resolve the contradiction, and just falls over. It’s not an exploit. It’s not a memory attack. It’s the software equivalent of asking someone to simultaneously pat their head and rub their stomach—except the someone is a phone that costs more than a month’s rent and the result is a hard reboot.

I’m not going to tell you exactly where to find the string. Partly because you already know where to look, and partly because you’re sending it to three people before dinner regardless. The bug was documented and reported, a patch eventually arrived, and the window closed. But for a brief, stupid moment, a text message could kill a phone. The internet, as always, found this absolutely delightful.