In this course, we will wear many hats. With our Attacker Hats on, we will exploit Injection issues that allow us to steal data, exploit Cross Site Scripting issues to compromise a users browser, break authentication to gain access to data and functionality reserved for the 'Admins', and even exploit vulnerable components to run our code on a remote server and access some secrets. We will also wear Defender Hats. We will dive deep in the code to fix the root cause of these issues and discuss various mitigation strategies. We do this by exploiting WebGoat, an OWASP project designed to teach penetration testing. WebGoat is a deliberately vulnerable application with many flaws and we take aim at fixing some of these issues. Finally we fix these issues in WebGoat and build our patched binaries. Together we will discuss online resources to help us along and find meaningful ways to give back to the larger Application Security community.