It said it was aware that the issue may have been exploited and cited Citizen Lab. Still, Apple said in a blog post it was issuing a security update for iPhones and iPads because a “maliciously crafted” PDF file could lead to them being hacked. Although security experts say that average iPhone, iPad and Mac user generally need not worry - such attacks tend to be highly targeted. The flaw discovered by Citizen Lab affected all of Apple’s operating systems, the researchers said. They said they had high confidence the Israeli company NSO Group was behind the attack, adding that the targeted activist asked to remain anonymous. It was the first time a so-called “zero-click” exploit had been caught and analyzed, said the researchers, who found the malicious code on Sept. The flaw was detected by researchers at the University of Toronto’s Citizen Lab, who noticed spyware from the world’s most infamous hacker-for-hire firm, NSO Group, had infected the iPhone of a Saudi activist. New details on Akron deadly fire that claimed lives of 3 children, 2 adults