A young Indian analyst has discovered a flaw in WhatsApp that allows you to block a single chat or a group by sending a message. Just a message with 4,000 smileys (emoticons) and the conversation freezes and becomes unusable.

The ” killer smiley faces” bug was discovered by Indian blogger Indrajeet Bhuyan , the same one who had discovered a similar error a few months ago that allowed WhatsApp to be blocked by sending a message of 2,000 words with a set of special characters.

The WhatsApp engineers immediately fixed that flaw, but now he will have to deal with the new bug:

too many smilies crash WhatsApp.

As reported by the 18-year-old blogger on Hackatrick, on WhatsApp Web the character limit for a message is 6,500, but when 4200-4400 emojis are entered the page becomes slow.

The interesting thing happens when you send the message:

both the WhatsApp application of whoever sends this message and that of whoever receives it are blocked.

There is no way to reopen the conversation.

The victim must cancel the chat to be able to talk to that person again.

The bug appears to affect 900 million WhatsApp users. Bhuyan showed that killer smilies can affect both WhatsApp Web  on Firefox and Chrome , as well as mobile versions for Android and iOS .

The difference is that the flaw on Android causes the application to close, while on iOS it causes a block that no longer allows you to use it.

The person receiving this emoticon string must delete the suspicious conversation and clear the chat history. This is the only way to reuse WhatsApp normally.

This security breach can have consequences of varying severity. “Suppose an attacker sent a malicious message or blackmail to the victim. Now, the victim cannot show the message as evidence, ”Bhuyan warns. “I reported the WhatsApp failure. We hope that in the next version it will be fixed ”, he concludes.