Morris exploited vulnerabilities in the programming logic of an application by employing input validation attacks such as XSS (Cross-Site Scripting). The presentation layer is responsible for handling user interfaces, rendering content, and managing interactions between users and the application. It deals with how data is presented to users and how user input is processed. By manipulating the presentation layer, Morris was able to compromise the application’s security. References: EC-Council Certified Security Specialist (E|CSS) documents and study guide 12.