WhatsApp security flaw could have hijacked users' computers, just by knowing their phone numbers

We all know that the WhatsApp messaging service is available for smartphones – there are hundreds of millions of mobile users of the service.

But some people want to have WhatsApp conversations on their desktop computer rather than their smartphone – and that’s why the Facebook-owned service has WhatsApp Web.

From WhatsApp Web you can send and receive messages, images, videos, audio files, even your location and contact cards. All from the comfort of your desktop browser.

So far, so good.

But security researchers at Check Point have discovered a serious vulnerability on the web-based WhatsApp that could be exploited by malicious attackers to infect the computers of users.

According to security researcher Kasif Dekel, all a malicious hacker needs to do is send a boobytrapped contact card (known as a vCard) to their intended victim. Once opened, the malicious code executes and infects the recipient’s PC.

Dekel gave the example of a message claiming to contain the contact details of Hollywood actress Angelina Jolie.

In the demonstration, attempting to open the contact card executes code which displays the word “HACKED” in a pop-up message box.

Thankfully, WhatsApp took the problem seriously when it was reported to them in August, and a patched version of WhatsApp was rolled out just six days later. Check Point waited a further 12 days before disclosing the vulnerability publicly, presumably to ensure that as many people as possible had benefited from the secured software.

This, it feels to me, is a responsible way to handle vulnerabilities. A security researcher stumbles across a serious flaw that definitely needs to be fixed – but rather than racing to Twitter to declare how clever he or she is, they instead contact the software manufacturer privately and work with them to get the issue resolved. They then wait until there is a good chance that no-one else will be able to actively exploit the flaw before releasing details and having their moment in the spotlight.

If only more vulnerability researchers worked this way, caring about the internet community as a whole rather than their personal glory.