Security researchers Charlie Miller and Collin Mulliner have announced that they will unveil a security hole that could allow the bad guys to hack "every iPhone in the world," and do so with relative ease. The issue involves an unpatched SMS Texting -- the technology used to send text messages between mobile phones -- buffer overflow hole that would allow a hacker to take over your iPhone by sending you 512 SMS messages, only one of which would be seen.

Worse, the visible message would show up as a single square character, and even that is subject to improvement (from the bad guys' perspective) to invisible characters, or something more benign.

Mr. Miller told Forbes magazine that he told Apple more than a month ago, but that the hole still had not been patched. He intends to demonstrate and publish it on Thursday at the Black hat cybersecurity conference in Las Vegas.

"This is serious. The only thing you can do to prevent it is turn off your phone," Miller told Forbes. "Someone could pretty quickly take over every iPhone in the world with this."

He added, "I've given them more time to patch this than I've ever given a company to patch a bug."

Once in control, the hacker could make phone calls with your phone (for instance, to 1.900 numbers that cost by the minute), send e-mails, or perpetrate the same attack against everyone in your Address Book, allowing it to spread quickly and easily.

Until the hole is patched, the only solution once you are infected is to turn your iPhone off.

Mr. Miller also said that a similar hole exists in the Windows Mobile, but that he had only discovered that on Monday, and had not yet notified Microsoft.

Mr. Miller has often made headlines in the Mac and iPhone press for publishing and demonstrating security holes in Mac OS X and the iPhone, and by winning multiple pwn2own contests that challenge hackers to take over a computing device remotely.