Arabic Text String Taking Down Apps, Clients, Browsers on iOS, Mac OS X

A bug in Apple’s Core Text technology is at the core of denial of service conditions on iOS and Mac OS X caused by a string of Arabic text making the rounds online.

A string of Arabic text is causing some chaos with iOS and Mac OS X users. It seems wherever the text sequence shows up, whether in a tweet, webpage, or a SMS message on the Apple platform, it’s crashing apps or Safari browser sessions.

The problem has been traced to the Apple Core Text technology which handles page layout and font rendering and has been available since OS X v10.5 and iOS 3.2.

From the online Apple programming guide: “The Core Text layout engine is designed specifically to make simple text layout operations easy to do and to avoid side effects. The Core Text font programming interface is complementary to the Core Text layout engine and is designed to handle Unicode fonts natively, unifying disparate OS X font facilities into a single comprehensive programming interface.”

A post on a Russian site,, said crashes are happening on Mac OS 10.8 and iOS 6; newer beta versions of both are not affected, the site said. The post also confirmed that SMS message, iMessages, and opening pages using Safari on iOS or OS X will crash the browser. It also said that renaming a Wi-Fi SSID with the text string will also result in errors while scanning for networks.

The site also said that Apple has known about the bug for six months. Apparently until yesterday, the string had been limited to the Russian site, but it’s quickly spread to social media today causing some denial-of-service angst as Twitter apps, browsers and SMS clients crash. Facebook, meanwhile, has already taken steps to block the code from wall posts and timelines.

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