MENLO PARK, Calif. (AP/CBS) - Spyware created by a sophisticated group of hackers-for-hire took advantage of a flaw in the WhatsApp communications program used by more than 1.5 billion people worldwide to remotely hijack dozens of phones, the company said late Monday.
The Financial Times identified the firm as Israel's NSO Group, and WhatsApp all but confirmed the identification.
WhatsApp described the hackers to CBS News as having "all the hallmarks of a private company that works with a number of governments around the world," adding to The Associated Press that they do so "to deliver spyware." A spokesman for the Facebook subsidiary later told the AP: "We're certainly not refuting any of the coverage you've seen."
WhatsApp also told CBS News, "We have made information available to U.S. law enforcement for further review. We may make additional information available as appropriate."
"WhatsApp encourages people to upgrade to the latest version of our app, as well as keep their mobile operating system up to date, to protect against potential targeted exploits designed to compromise information stored on mobile devices," the spokesman said to CBS News. "We are constantly working alongside industry partners to provide the latest security enhancements to help protect our users."
The malware was able to penetrate phones through missed calls alone via the app's voice calling function, the spokesman told AP. An unknown number of people - an amount in the dozens at least would not be inaccurate - were infected with the malware, which the company discovered in early May, said the spokesman, who was not authorized to be quoted by name.
In the past, NSO's spyware has repeatedly been found deployed to hack journalists, lawyers, human rights activists and dissidents.
John Scott-Railton, a researcher with the internet watchdog Citizen Lab, called the latest hack "a very scary vulnerability."
"There's nothing a user could have done here, short of not having the app," he said.
The spokesman said the flaw was discovered while "our team was putting some additional security enhancements to our voice calls" and that engineers found that people targeted for infection "might get one or two calls from a number that is not familiar to them. In the process of calling, this code gets shipped."
WhatsApp immediately contacted Citizen Lab and human rights groups, quickly fixed the issue and pushed out a patch. "We are deeply concerned about the abuse of such capabilities," WhatsApp said in a statement.