PSE-STRATA Question #122: Real Exam Question with Answer & Explanation

A customer is targeted by a true zero-day, targeted attack. However, the customer is protected by the Palo Alto Networks security platform. The attack leverages a previously unknown vulnerability in IE but utilizes existing hacking techniques on the endpoint. It is transported over standard HTTP traffic and conforms to the HTML standards. It then attempts to download from a website, compromised specifically for this attack, a custom piece of malware to run on the endpoints. Which element of the platform will stop this attack?