WebAssembly is the new binary instruction format for the web, finally giving an alternative to JavaScript as the only portable programming language supported by web browsers. An important way of analyzing WebAssembly applications will be dynamic analyses, but implementing a dynamic analysis from scratch is non-trivial.

This tutorial gives a gentle introduction to Wasabi, a general-purpose framework for easily implementing heavyweight dynamic analyses of WebAssembly code. Wasabi is based on ahead-of-time byte code instrumentation, which inserts calls to analysis hooks in between the original program’s instructions. These hooks, written in JavaScript by the analysis author, enable the implementation of powerful dynamic analyses, e.g., taint analysis, memory profilers, coverage measurements, or detectors of cryptocurrency mining.

The tutorial will explain the design of Wasabi and give a hands-on introduction to writing dynamic analysis for WebAssembly. Participants will run a simple web application containing WebAssembly code, apply Wasabi to it, and implement a sequence of increasingly complex analyses under the guidance of the creators of Wasabi.

For more information about the tutorial, please refer to http://wasabi.software-lab.org/tutorial-pldi2019/.