Controlling spam and spear phishing via peered network overlays and non-repudiable traceback

Despite 30 years of on-going effort, spam remains a significant problem. While technology has abated the deluge of spam invading the average user's email inbox, spam still facilitates the sale of counterfeited products, distribution of malware, and other criminal activities - as well as the more insidious use of spear phishing to leverage attacks into corporate and government networks. The value of email arises directly from its anyone-to-anyone message-passing capability. Hence, anti-spam techniques based on end-point encryption have met with limited success. Furthermore, due to geopolitical concerns, most traceback techniques only work effectively within - and not across - geopolitical boundaries; and while targeted removal of spam-friendly ISPs and botnets has had significant impacts on spam rates, these gains have tended to be short lived. This work proposes a novel approach to control spam and spear phishing through combining peer-level quality-of-service (QoS) agreements with a ProVerif verified, non-repudiable traceback protocol to enact spam resistant overlays that are: i) scalable, ii) enforceable over geopolitical boundaries, and iii) do not require technological sea changes. Simulation results on an Internet-style network of 3,000 ISPs show that even in the presence of aggressive spammers, it is possible to reduce the spam versus normal email equilibrium from 90:10 to 20:80. Furthermore, this approach can be used to aid in controlling spear phishing attacks targeting federated organizations.