by @frohoff and @gebl
Note: see the more recent presentation on Java Deserialization: Deserialize My Shorts: Or How I Learned To Start Worrying and Hate Java Object Deserialization
Object serialization technologies allow programs to easily convert in-memory objects to and from various binary and textual data formats for storage or transfer – but with great power comes great responsibility, because deserializing objects from untrusted data can ruin your day. We will look at historical and modern vulnerabilities across different languages and serialization technologies, including Python, Ruby, and Java, and show how to exploit these issues to achieve code execution. We will also cover some strategies to protect applications from these types of attacks.
ysoserial is a collection of utilities and property-oriented programming "gadget chains" discovered in common java libraries that can, under the right conditions, exploit Java applications performing unsafe deserialization of objects. The main driver program takes a user-specified command and wraps it in the user-specified gadget chain, then serializes these objects to stdout. When an application with the required gadgets on the classpath unsafely deserializes this data, the chain will automatically be invoked and cause the command to be executed on the application host.