The revelation adds to the questions over the reach of the Israeli company's powerful spyware, which can hijack mobile phones, control their cameras and effectively turn them into pocket-sized surveillance devices.
The spyware gave hackers the ability to take over the functions of mobile phone operating systems remotely. The spyware, called Pegasus, has also been implicated in the tragic killing of Saudi journalist Jamal Khashoggi who was killed in the Saudi consulate in Israel past year and whose body is yet to be found. "It is an unprecedented security flaw in terms of its potential to run high-profile targeted attacks".
Under My apps and games, tap update next to WhatsApp Messenger.
John Scott-Railton, a researcher with the internet watchdog Citizen Lab, called the hack "a very scary vulnerability".More news: Trump raises tariffs on $200 billion of Chinese goods, prompting Chinese warning
"There's nothing a user could have done here, short of not having the app", he said. The vast majority of hacks involve some sort of user interaction, such as clicking on an infected link. At first, engineers were surprised by the information that many users got calls from an unfamiliar number.
WhatsApp said it has notified European data privacy regulators of the breach and has also provided USA law enforcement information to conduct an investigation. "That's really where our highest concern is", a WhatsApp spokesman said.
If you received a unusual phone call on your WhatsApp in recent weeks, you may have been the victim of a cyber crime - even if you didn't answer the call.
The NSO denies any links to the attack and insists that "under no circumstances" would it be involved in "the operating or identifying of targets of its technology".More news: Campaigning in WB to end tomorrow after EC's unprecedented action
Many journalists, dissidents, activists, and lawyers have reported attacks by NSO's spyware.
In a January interview with Israeli daily Maariv, Hulio was asked about reports that telephone spyware was used to bug Jamal Khashoggi prior to the Saudi journalist´s killing last October in Istanbul.
NSO Group describes itself as a developer of "technology that helps government agencies prevent and investigate terrorism and crime to save thousands of lives around the globe".
Human rights groups filed a petition in an Israeli court this week asking the government to revoke the license of a cybersecurity firm that reportedly created a type of malware that enabled attackers to spy on users of the popular messaging platform WhatsApp.More news: Reynolds leads Rockies past Red Sox in 11th
Ireland's Data Protection Commission, which supervises Facebook's activities in Europe, said it had been informed of the vulnerability on Monday, adding it was unclear at this stage whether any European Union user data had been affected.