The Trident is a chain of zero-day exploits that aim to infect iPhone with commercial spyware. Researchers say its belonging to an exploit infrastructure connected to the NSO group. Apple worked extremely quickly to patch these vulnerabilities and it has released iOS 9.3.5 to address them. In short, we want to give you a description and some technical information about the inner logic of the Trident exploit instead of the attack received by Ahmed Mansoor. The exploit seems to contain the logic to remote jailbreak an iPhone to install arbitrary applications and then deliver spyware called Pegasus as an espionage software to track the victim.”]
Source: http://securityaffairs.co/wordpress/50788/mobile-2/ios-9-3-4-trident-exploit.html