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.