Adding specific symbols to a message makes it possible to crash Whatsapp on Android smartphones. The symbols that make Whatsapp crash are normally used to tell the smartphone to reverse the text direction. In the worst cases, it might even make the phone hang or reboot.
It’s not the first time Whatsapp can be made to crash with specific characters, emoji or symbols. In February this year a method appeared that made it possible to crash iPhones with an obscure Indian character. This time the Whatsapp messages don’t contain any strange looking characters, the symbols that make Whatsapp crash on Android are not visible to the user, they are hidden.
When the user is tricked into tapping the hidden symbols, which is done by asking the user to tap on something close to the hidden symbol, the symbols are normally expanded and for some reason this crashes Whatsapp and in some cases, even the phone.
There are currently two variants making the rounds on Whatsapp, one message contains a message stating, “If you touch this black dot then your WhatsApp will hang.”
Next to the message is a finger emoji pointing to a black dot emoji. In between, the special symbols are hidden, so that when the user taps near the black dot, Whatsapp will indeed hang. Another variant shows the message, “This is very interesting,” followed by an emoji. Again the special symbols are close the emoji and when tapped, Whatsapp or the entire phone will hang.
The special symbols are “&rlml;” and “‏” which are used to reverse text direction. In English, and many other languages, text is read from left to right. But in e.g. Arabic and Hebrew, this is from right to left. By adding either symbol, the text direction for a specific word can be reversed. That’s also why it isn’t visible, it’s not intended for the user’s eyes, it’s only there to command the phone to display the text in the reverse direction.
While most English-speaking users will normally never use the symbols, they are now hidden in message with a single purpose, to crash Whatsapp of the recipient.