NATIONWIDE — Anyone using the popular communications tool What's App should update it immediately. 

Tech researchers say the software could use the microphone and camera on cellphones to listen to and even look at users through the phone.

Spyware crafted by a sophisticated group of hackers-for-hire took advantage of a flaw in WhatsApp to remotely hijack dozens of phones without any user interaction.

The Financial Times identified the hacking group as Israel’s NSO Group, which has been widely condemned for selling surveillance tools to repressive governments.

WhatsApp all but confirmed the identification, describing hackers as "a private company that has been known to work with governments to deliver spyware."

A spokesman for the Facebook subsidiary later said: "We’re certainly not refuting any of the coverage you’ve seen."

WhatsApp has released a new version of the app containing a fix.

The spyware did not directly affect the end-to-end encryption that makes WhatsApp chats and calls private. It merely used a bug in the WhatsApp software as an infection vehicle. 

The malware allows spies to effectively take control of a phone — remotely and surreptitiously controlling its cameras and microphones and vacuuming up personal and location data. Encryption is worthless once a phone’s operating system has been violated.

Hackers are always looking for flaws in apps and operating systems that they can exploit to deliver spyware. State-run intelligence agencies including the U.S. National Security Agency invest tens of millions of dollars on it. 

Indeed, Google’s ProjectZero bug-hunting team scoured WhatsApp last year looking for vulnerabilities but did not find any. 

Instead, it was WhatsApp’s security team that found the flaw.

Although WhatsApp urged all users to update the program on their phones, only a minuscule percentage run the risk of being targeted by such malware.

Information from the Associated Press was used in this report.