Pareto-Optimal Defenses for the Web Infrastructure: Theory and Practice

Abstract

The integrity of the content a user is exposed to when browsing the web relies on a plethora of non-web technologies and an infrastructure of interdependent hosts, communication technologies, and trust relations. Incidents like the Chinese Great Cannon or the MyEtherWallet attack make it painfully clear: the security of end users hinges on the security of the surrounding infrastructure: routing, DNS, content delivery, and the PKI. There are many competing, but isolated proposals to increase security, from the network up to the application layer. So far, researchers have focus on analyzing attacks and defenses on specific layers. We still lack an evaluation of how, given the status quo of the web, these proposals can be combined, how effective they are, and at what cost the increase of security comes. In this work, we propose a graph-based analysis based on Stackelberg planning that considers a rich attacker model and a multitude of proposals from IPsec to DNSSEC and SRI. Our threat model considers the security of billions of users against attackers ranging from small hacker groups to nation-state actors. Analyzing the infrastructure of the Top 5k Alexa domains, we discover that the security mechanisms currently deployed are ineffective and that some infrastructure providers have a comparable threat potential to nations. We find a considerable increase of security (up to 13% protected web visits) is possible at relatively modest cost, due to the effectiveness of mitigations at the application and transport layer, which dominate expensive infrastructure enhancements such as DNSSEC and IPsec.