Be careful out there, iPhone users: a simple three-character combination, when send as a message, can crash and freeze your friend's iPhone

The trick, publicly unveiled on YouTube channel EverythingApplePro, does not work on every iPhone and is not that simple to pull off, but it works, with pretty nasty results.

The message-of-death consists three visible characters: a white flag, a zero and a rainbow emoji, as well as an invisible character, called variation sector 16 or VS16. When the message is received, the VS16 signals the iPhone's Messages app to combine the two emoji into one, which cannot be done and can cause the app to crash and the phone to freeze.

The worst thing about this bug is that the recipient does not even have to interact with the message; the moment you receive it on your iPhone, it will freeze.

There are two caveats to this trick. First, it doesn't work on the latest version of iOS, 10.2.1 (it works on versions 10.0 through 10.1.1), meaning all you have to do is upgrade your iOS and you'll be safe. Second, it's not as simple as sending a text message from one phone to another; the process requires logging into iCloud, pasting the character string into the online version of Notes, then opening that on a phone and sharing it as a message.

It doesn't end here, though. EverythingApplePro shared another trick that can freeze iPhones, and this one works even on the latest version of iOS. This message involves a longer string of characters, but it can be sent directly from one iPhone to another.

Do not try this; it's not only dangerous for others, but can also be dangerous for your own phone.

The process is much more convoluted, but — in most cases — it does not completely crash the recipient's iPhone, but it slows it down and is generally quite annoying.

We put the second method to the test, sending the killer message from an iPhone 7 to an iPhone 6S, which were both running iOS 10.2. In two trials, we didn't experience anything more than just a slight slowdown in Messages. The 6S received the text and froze momentarily both times, but after a few seconds, the system was running normally as if nothing had happened. It was annoying for a moment, sure — but it wasn't nearly as dramatic as EverythingApplePro claims in the video.

We do not recommend trying either method out unless you're a security researcher, especially not on someone else's phone. If for no other reason, don't do it as it requires going to a third-party web page which might contain malicious code and infect your own iPhone with malware.

We've recently seen several similar bugs that can render an iPhone useless, such as this video or this link, both of which cause an iPhone to crash. Apple generally fixes them fast. In this case, one of the bugs has already been fixed — hopefully Apple will soon find a cure for the other one as well.