Lyft’s whole app experience is geared towards getting new users from the App Store or the Play Store to their first ride as quickly as possible. This streamlined process is great for users, but presents an ever-present problem — how do we prevent bad actors from abusing the lightweight onboarding process? In this talk, Dr. King will discuss how the best way to protect accounts is by changing products. He will describe the systems and techniques used at Twitter and Lyft to secure user's accounts, as well as extract general principles on how one should go about changing products to improve security. He will also discuss his research lab's recent work on preventing card-not-present - credit card fraud, where deep learning is used to create and detect fake credit cards.