Apple issued a patch on Thursday to fix a security flaw in iPhones and iPads after researchers discovered that a prominent United Arab Emirates dissident's phone had been targeted with a previously unknown method of hacking. The spyware takes advantage of three previously undisclosed weaknesses in Apple's mobile operating system to take complete control of iPhone handsets.

Two reports published Thursday by the San Francisco-based Lookout and University of Toronto's Citizen Lab outlined how the spyware could compromise an iPhone with the tap of a finger, a trick so coveted in the world of cyberespionage that one spyware broker said last year that it had paid a $1 million dollar bounty to programmers who'd found a way to do it.

The attack on the human rights activist, Ahmed Mansoor, used a text message that invited him to click on a web link. Instead of clicking, he forwarded the message to researchers at the University of Toronto's Citizen Lab.

The hack is the first known case of software that can remotely take over a fully up-to-date iPhone 6.

"Once infected, Mansoor’s phone would have become a digital spy in his pocket, capable of employing his iPhone’s camera and microphone to snoop on activity in the vicinity of the device, recording his WhatsApp and Viber calls, logging messages sent in mobile chat apps, and tracking his movements," Citizen Lab wrote in a report released on Thursday.

The researchers said they had alerted Apple a week and a half ago, and the company developed a fix and distributed it as an automatic update to iPhone 6 owners.

Apple said in a statement that it fixed the vulnerability immediately after learning about it. The latest iOS version 9.3.5 fixes the issues.