Once the spyware is installed, it allows hackers to listen in to calls made using WhatsApp's voice function. Attackers are exploiting a software flaw to wiretap people's phones.
The flaw reportedly allows attackers/hackers to install malicious code, known as "spyware", on iPhones and Android phones by ringing up the target device.
The code can be transmitted even if the user does not answer the phone and a log of the call often disappears.