Towards sender accountability on email infrastructure using sender identity and reputation management

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

Secure Identity Management Framework for Vehicular Ad-hoc Network using Blockchain

Vehicular Ad Hoc Network (VANET) is a mobile network formed by vehicles, roadside units, and other infrastructures that enable communication between the nodes to improve road safety and traffic control. While this technology promises great benefits to drivers, it has many security concerns that are critical to road safety. It is essential to ensure that only authenticated vehicles transmit data and revoked vehicles do not interfere in this communication. Many current VANET technologies also depend on a central trusted authority that can cost computation and communication overhead and be a single point of failure for the network. By using blockchain technology in VANET, we can take advantage of the decentralized and distributed framework and thereby avoid a single point of trust. Moreover, blockchain technology ensures the immutability of the data strengthening the integrity of the system. In the proposed framework, Hyperledger Fabric, a permissioned blockchain technology, is used for identity management in VANET. All the vehicles with their pseudo IDs are registered, validated, and revoked using the blockchain technology. The vehicles in the network check the validity of the safety messages received from the neighboring nodes, using the services provided by the road side units that have access to the blockchain. This framework works on looking-up the pseudo IDs and public keys on the blockchain for their validity, thus promising a light-weight authentication and reduced computation and communication overhead for vehicles to access the safety messages in the network

Towards secure message systems

Message systems, which transfer information from sender to recipient via communication networks, are indispensable to our modern society. The enormous user base of message systems and their critical role in information delivery make it the top priority to secure message systems. This dissertation focuses on securing the two most representative and dominant messages systems---e-mail and instant messaging (IM)---from two complementary aspects: defending against unwanted messages and ensuring reliable delivery of wanted messages.;To curtail unwanted messages and protect e-mail and instant messaging users, this dissertation proposes two mechanisms DBSpam and HoneyIM, which can effectively thwart e-mail spam laundering and foil malicious instant message spreading, respectively. DBSpam exploits the distinct characteristics of connection correlation and packet symmetry embedded in the behavior of spam laundering and utilizes a simple statistical method, Sequential Probability Ratio Test, to detect and break spam laundering activities inside a customer network in a timely manner. The experimental results demonstrate that DBSpam is effective in quickly and accurately capturing and suppressing e-mail spam laundering activities and is capable of coping with high speed network traffic. HoneyIM leverages the inherent characteristic of spreading of IM malware and applies the honey-pot technology to the detection of malicious instant messages. More specifically, HoneyIM uses decoy accounts in normal users\u27 contact lists as honey-pots to capture malicious messages sent by IM malware and suppresses the spread of malicious instant messages by performing network-wide blocking. The efficacy of HoneyIM has been validated through both simulations and real experiments.;To improve e-mail reliability, that is, prevent losses of wanted e-mail, this dissertation proposes a collaboration-based autonomous e-mail reputation system called CARE. CARE introduces inter-domain collaboration without central authority or third party and enables each e-mail service provider to independently build its reputation database, including frequently contacted and unacquainted sending domains, based on the local e-mail history and the information exchanged with other collaborating domains. The effectiveness of CARE on improving e-mail reliability has been validated through a number of experiments, including a comparison of two large e-mail log traces from two universities, a real experiment of DNS snooping on more than 36,000 domains, and extensive simulation experiments in a large-scale environment

Plugging the “Phishing” Hole: Legislation Versus Technology

This iBrief analyzes the Anti-Phishing Act of 2005, legislation aimed at curbing the problem of phishing. Phishing is the sending of fraudulent emails which appear to be from legitimate businesses and thereby fooling the recipients into divulging personal information such as credit card numbers. While this legislation may provide some assistance in the fight against phishing, it is limited by the global nature of the Internet and the ease with which phishers can hide and avoid judgments. This iBrief therefore concludes that although the Anti-Phishing Act can play a supporting role in the battle, technological solutions are the most effective means of reducing or eliminating phishing attacks

Plugging the “Phishing” Hole: Legislation Versus Technology

This iBrief analyzes the Anti-Phishing Act of 2005, legislation aimed at curbing the problem of phishing. Phishing is the sending of fraudulent emails which appear to be from legitimate businesses and thereby fooling the recipients into divulging personal information such as credit card numbers. While this legislation may provide some assistance in the fight against phishing, it is limited by the global nature of the Internet and the ease with which phishers can hide and avoid judgments. This iBrief therefore concludes that although the Anti-Phishing Act can play a supporting role in the battle, technological solutions are the most effective means of reducing or eliminating phishing attacks

Improving privacy in identity management systems for health care scenarios

Privacy is a very complex and subjective concept with different meaning to different people. The meaning depends on the context. Moreover, privacy is close to the user information and thus, present in any ubiquitous computing scenario. In the context of identity management (IdM), privacy is gaining more importance since IdM systems deal with services that requires sharing attributes belonging to users’ identity with different entities across domains. Consequently, privacy is a fundamental aspect to be addressed by IdM to protect the exchange of user attributes between services and identity providers across different networks and security domains in pervasive computing. However, problems such as the effective revocation consent, have not been fully addressed. Furthermore, privacy depends heavily on users and applications requiring some degree of flexibility. This paper analyzes the main current identity models, as well as the privacy support presented by the identity management frameworks. After the main limitations are identified, we propose a delegation protocol for the SAML standard in order to enhance the revocation consent within healthcare scenarios.Proyecto CCG10-UC3M/TIC-4992 de la Comunidad Autónoma de Madrid y la Universidad Carlos III de Madri

Improving and distributing key management on mobile networks

We address the problem of mobile network key management and authentication that negatively affects the handoff performance, adds overhead to the system in terms of key exchange signaling, authentication, and key distribution. We aim to improve the efficiency of the key management subsystem and to reduce investment pressure on core network elements. We address all these problems successfully. Our novel SKC key management mechanism is the best key management mechanism among the ones we found in reducing signaling load from the KD and making the mobility system independent of the AP-KD link delay. It is a significant contribution to the mobile network key management with fast handoffs when separate keys for APs are required and has many useful applications. Our novel receiver and sender ID binding protocol with symmetric keys is new and shows analogy with Identity Based Cryptography. It is a generalization of the identity binding that SKC is using. Furthermore, our distributed AAA architecture with SKC, certificates, and hardware-based security is a disruptive proposal and show how the mobile network KD can be distributed to the edge nodes. Our quantitative analysis and comparison of SKC and LTE key management is new and not seen before. Our research affected the LTE Security standardization and contributes to the research and development of home base stations, community and municipal Wi-Fi access points

Security in heterogeneous wireless networks

The proliferation of a range of wireless devices, from the cheap low power resource starved sensor nodes to the ubiquitous cell phones and PDA\u27s has resulted in their use in many applications. Due to their inherent broadcast nature Security and Privacy in wireless networks is harder than the wired networks. Along with the traditional security requirements like confidentiality, integrity and non-repudiation new requirements like privacy and anonymity are important in wireless networks. These factors combined with the fact that nodes in a wireless network may have different resource availabilities and trust levels makes security in wireless networks extremely challenging. The functional lifetime of sensor networks in general is longer than the operational lifetime of a single node, due to limited battery power. Therefore to keep the network working multiple deployments of sensor nodes are needed. In this thesis, we analyze the vulnerability of the existing key predistribution schemes arising out of the repeated use of fixed key information through multiple deployments. We also develop SCON, an approach for key management that provides a significant improvement in security using multiple key pools. SCON performs better in a heterogeneous environment. We present a key distribution scheme that allows mobile sensor nodes to connect with stationary nodes of several networks. We develop a key distribution scheme for a semi ad-hoc network of cell phones. This scheme ensures that cell phones are able to communicate securely with each other when the phones are unable to connect to the base station. It is different from the traditional ad hoc networks because the phones were part of a centralized network before the base station ceased to work. This allows efficient distribution of key material making the existing schemes for ad hoc networks ineffective. In this thesis we present a mechanism for implementing authenticated broadcasts which ensure non-repudiation using identity based cryptography. We also develop a reputation based mechanism for the distributed detection and revocation of malicious cell phones. Schemes which use the cell phone for secure spatial authentication have also been presented