Which single digit has the highest value in the hexadecimal number system?

Scenario: 1. victim opens the attacker's web site. 2. attacker sets up a web site which contains interesting and attractive content like 'do you want to make $1000 in a day? '. 3. victim clicks to the interesting and attractive content url. 4. attacker creates a transparent 'iframe' in front of the url which victim attempt to click, so victim thinks that he/she clicks to the 'do you want to make $1000 in a day? ' url but actually he/she clicks to the content or url that exists in the transparent 'iframe' which is setup by the attacker. what is the name of the attack which is mentioned in the scenario?