Towards Sender Accountability on Email Infrastructure using Sender Identity and Reputation Management
1 online resource (97 pages) : PDF
University of North Carolina at Charlotte
Email Infrastructure has grown exponentially, since the early days of ARPANET, to support millions of users. However, the extensive adoption of the original open design has led to security implications. As claimed in recent statistics, about 95% of the emails are unsolicited and place phishing losses at $500 million. Even though, current email-filtering technologies weed out most of the incoming spam, there is a need to hold senders accountable for their email behavior. Without sender accountability, there is no way to hold senders responsible for their online email behavior. Holding senders accountable helps identify senders who propagate spam, and possibly reduce the spam transmitted.Holding a sender accountable for the sender's online activity requires: first, the sender's identification; and second, maintenance of its historical email activity. Today, widely deployed sender identity techniques counteract email spoofing by authenticating the sender's email server to the receiver organizations. Unfortunately, these techniques are not as effective as originally intended as: a) the senders create their own identity; b) spam-propagating senders have adopted these technologies. Knowledge of the sender's identity alone does not guarantee its adherence to email best practices. Towards establishing sender accountability, this dissertation proposes RepuScore, a collaborative reputation framework that allows participating receiver organizations to share sender's behavioral patterns. In addition, this dissertation also explores Privilege Messaging (P-Messaging) framework, a fine-granular sender-authorization framework where each sender holds a set of credentials (privileges) to send an email; the receivers verify the attached credentials before accepting the emails. P-Messaging attempts to maintain trust among organizations with the help of a central authority, which periodically verifies the participating organization's adherence to good email practices. To create a long-standing history, participating organizations locally collect information about the senders - from users or existing spam classification mechanisms that are submitted to a central RepuScore authority - to compute a global reputation summary. This dissertation discusses the distributed architecture and the algorithms designed to compute reputation based on the sender's a) spam rate (RepuScore) or b) spam rate and email volume (Volume-Enhanced RepuScore). Additionally, the dissertation shares findings from experiments based on a RepuScore prototype using a) simulation logs; and b) deployed SpamAssassin plug-in since 10/9/2007 at three organizations. Based on the deployment, reputation for about 90,000 sender identities and about 12 million IP addresses as of Feb 2009 have been computed. We note that email classification using RepuScore is 97.8% accurate.Finally, this dissertation discusses future directions for Distributed RepuScore that allows organizations to maintain their personal reputation view to be shared among trusted peers. Distributed RepuScore enables a global reputation view while holding senders accountable at each organization instead of deploying it at a central authority.
EMAIL INFRASTRUCTUREPHISHINGREPUSCOREREPUTATION MANAGEMENTSENDER IDENTITYSPAM
Raja, AnitaWu, XintaoCathey, Jack
Thesis (Ph.D.)--University of North Carolina at Charlotte, 2009.
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