If you receive an iPhone text message with a "single square character," be afraid. Be very afraid. It's could be hackers using a iewly discovered iPhone SMS bug to infiltrate your precious phone. According to CBS 5. "Famed hacker Charlie Miller discovered the flaw and told Apple about it six weeks ago. The company has not issued a fix, so Miller will pressure Apple by showing exactly how to hijack the iPhone at a cybersecurity conference on Thursday." Miller warned yesterday, "Someone could pretty quickly take over every iPhone in the world with this." IntoMobile explains how it works: "Using the exploit, hackers could send a succession of SMS text messages to an iPhone, allowing them to gain complete control of the handset. Hackers can then commandeer the iPhone to send similar text message strings to other iPhones, spreading like wildfire." If you get this square-character message, there's not much you can do other than turn your phone off.