By the time you've seen this text, it's probably too late. If you're using an Apple product, that is.
A strange but simple bug in an essential part of Apple's desktop and mobile operating systems is crashing computers, phones, and tablets across the internet, as Windows and Firefox users, both immune, repost it for kicks. It's shown up on Reddit, 4Chan, YouTube, and Twitter, where it caused temporary chaos, and has already been banned from Facebook.
More damaging, and mostly invisible, is its potential spread via text — sending this string in iMessage in iOS 6 causes a crash that can leave phones severely disabled, and, for most users, prompt a trip to the genius bar.
This string of Arabic characters, which has no meaning, exploits a problem with Apple's Core Text rendering engine, which is the part of its operating system software that draws, smooths, and lays out text. To fix the bug users will have to update their operating systems, either in a small increment or to iOS 7 or the next version of OS X, Mavericks, neither of which have been released to the public but both of which are protected from the problem.
This exploit has limits as a destructive tool on its own. It's unlikely to go viral on its own given the percentage of viewers whose browsers it will crash. But as a part of an actual hack — the kind that the Syrian Electronic Army has been undertaking lately — it could cause serious inconvenience. Imagine the New York Times hadn't just been hacked last week, but that its homepage had redirected to this text. And as a tool for trolls, it's hard to beat.
For now, the best recourse for Mac users is to install Firefox and keep an eye out for incoming system updates.