WhatsApp's logo on a smartphone. Picture: EPA/RITCHIE B TONGO
WhatsApp's logo on a smartphone. Picture: EPA/RITCHIE B TONGO

Paris — Researchers at an Israeli cybersecurity firm say they have found a flaw in WhatsApp that could allow hackers to modify and send fake messages in the popular social messaging app.

The vulnerability could make it possible for a hacker "to intercept and manipulate messages sent by those in a group or private conversation" as well as "create and spread misinformation", CheckPoint said on Wednesday.

The Facebook-owned company is coming under increasing scrutiny as a means of spreading misinformation, due to its popularity and convenience for forwarding messages to groups.

In July WhatsApp announced limits on forwarding messages, in response to threats by the Indian government to take action.

That followed the killings of more than 20 people by crazed mobs, after they were accused of child kidnapping and other crimes in viral messages circulated wildly on WhatsApp.

WhatsApp said on Wednesday: "We carefully reviewed this issue and it’s the equivalent of altering an e-mail to make it look like something a person never wrote."

However, WhatsApps said: "This claim has nothing to do with the security of end-to-end encryption, which ensures only the sender and recipient can read messages sent on WhatsApp."

WhatsApp said it had recently placed a limit on forwarding content, added a label to forwarded messages, and made a series of changes to group chats in order to tackle the challenge of misinformation.

Founded in 2009 and purchased by Facebook in 2014, WhatsApp said that at the beginning of the year it had more than 1.5-billion users who exchanged 65-billion messages per day.