Mainframe systems continue to drive global economic activity despite the “legacy” label they are often associated with. In fact, mainframes are responsible for business-critical functions across 70 percent of Fortune 500 companies. If you have ever withdrawn cash at an ATM, done your taxes online, or booked a flight for your next holiday, you have likely interacted with a mainframe application. As with all business-critical systems, ensuring they are secure is imperative. This talk is designed for anyone interested in the security of these mainframe applications. We will go over how mainframe systems work, why they are so important, how the applications work, how they are used, and how the researchers were able to exploit a number of vulnerabilities in real world mainframe applications.