Establishing Browser Security Guarantees through Formal Shim Verification

Web browsers mediate access to valuable private data in domains ranging from health care to banking. Despite this critical role, attackers routinely exploit browser vulnerabilities to exfiltrate private data and take over the underlying system. We present QUARK, a browser whose kernel has been implemented and verified in Coq. We give a specification of our kernel, show that the implementation satisfies the specification, and finally show that the specification implies several security properties, including tab non-interference, cookie integrity and confidentiality, and address bar integrity.