Security researcher Charlie Miller has revealed that Apple is working on a patch for a security flaw he identified in the iPhone's SMS implementation. The flaw can actually lead to arbitrary code execution, as he explained to Ars last month. Miller hasn't yet detailed the flaw, citing an agreement with Apple, though he and partner Vincenzo Iozzo plan to detail their discovery later this month at the Black Hat Security Conference in Las Vegas.

During a presentation at the SyScan security conference in Singapore, Miller explained that a vulnerability in the iPhone's handling of SMS messages makes it possible to send code instead of strictly text. Despite SMS's 140 byte size limitation, the iPhone can reassemble larger messages that are broken up to fit the limitation, which allows larger programs to be sent. The iPhone can be instructed to execute SMS data as code instead of text, and when it executes the code it does so with root privileges and without any interaction from the user.