Open-source modules on the NPM ecosystem are undoubtedly awesome. However, they also represent an undeniable and massive risk. You’re introducing someone else’s code into your system, often with little or no scrutiny. The wrong package can introduce severe vulnerabilities into your application, exposing your application and your user’s data. This talk will use a sample application, Goof, which uses various vulnerable dependencies, which we will exploit as an attacker would. For each issue, we’ll explain why it happened, show its impact, and – most importantly – see how to avoid or fix it.