Smart contract security is a brave, new, and sometimes terrible field. This presentation will take you through some of the most famous vulnerabilities of these first few years (from the Dao hack, to the Parity wallet vulnerabilities ... and including less-well-known but very interesting events like the DDOS attacks from late 2016). We'll explain the details of how these attacks work(ed), some of the idiosyncrasies of Ethereum, and through these examples some general principles of smart contract security.