The detected spyware was Israel-based NSO Group's Pegasus.
WhatsApp has reportedly fixed a bug that allowed hackers to remotely install WhatsApp on phones.
The vulnerability, documented on Facebook, describes the vulnerability in WhatsApp VOIP stack that allowed the caller to allow the installation of commercial-grade spyware on the target number whether the call was answered or not, TechCrunch explained.
The detected spyware was Israel-based NSO Group's Pegasus, which is licensed to governments looking to infect targets of investigations. WhatsApp has closed the loophole that affected Android, iOS, Windows, and Tizen.