Systematization of threats and requirements for private messaging with untrusted servers. The case of E-mailing and instant messaging

Modern email and instant messaging applications often offer private communications. In doing so, they share common concerns about how security and privacy can be compromised, how they should face similar threats, and how to comply with comparable system requirements. Assuming a scenario where servers may not be trusted, we review and analyze a list of threats specifically against message delivering, archiving, and contact synchronization. We also describe a list of requirements intended for whom undertakes the task of implementing secure and private messaging. The cryptographic solutions available to mitigate the threats and to comply with the requirements may differ, as the two applications are built on different assumptions and technologies

GTmoPass: Two-factor Authentication on Public Displays Using Gaze-touch Passwords and Personal Mobile Devices

As public displays continue to deliver increasingly private and personalized content, there is a need to ensure that only the legitimate users can access private information in sensitive contexts. While public displays can adopt similar authentication concepts like those used on public terminals (e.g., ATMs), authentication in public is subject to a number of risks. Namely, adversaries can uncover a user's password through (1) shoulder surfing, (2) thermal attacks, or (3) smudge attacks. To address this problem we propose GTmoPass, an authentication architecture that enables Multi-factor user authentication on public displays. The first factor is a knowledge-factor: we employ a shoulder-surfing resilient multimodal scheme that combines gaze and touch input for password entry. The second factor is a possession-factor: users utilize their personal mobile devices, on which they enter the password. Credentials are securely transmitted to a server via Bluetooth beacons. We describe the implementation of GTmoPass and report on an evaluation of its usability and security, which shows that although authentication using GTmoPass is slightly slower than traditional methods, it protects against the three aforementioned threats

Authentication and Key Management Automation in Decentralized Secure Email and Messaging via Low-Entropy Secrets

We revisit the problem of entity authentication in decentralized end-to-end encrypted email and secure messaging to propose a practical and self-sustaining cryptographic solution based on password-authenticated key exchange (PAKE). This not only allows users to authenticate each other via shared low-entropy secrets, e.g., memorable words, without a public key infrastructure or a trusted third party, but it also paves the way for automation and a series of cryptographic enhancements; improves security by minimizing the impact of human error and potentially improves usability. First, we study a few vulnerabilities in voice-based out-of-band authentication, in particular a combinatorial attack against lazy users, which we analyze in the context of a secure email solution. Next, we propose solving the problem of secure equality test using PAKE to achieve entity authentication and to establish a shared high-entropy secret key. Our solution lends itself to offline settings, compatible with the inherently asynchronous nature of email and modern messaging systems. The suggested approach enables enhancements in key management such as automated key renewal and future key pair authentications, multi-device synchronization, secure secret storage and retrieval, and the possibility of post-quantum security as well as facilitating forward secrecy and deniability in a primarily symmetric-key setting. We also discuss the use of auditable PAKEs for mitigating a class of online guess and abort attacks in authentication protocols

Mitigating Denial-of-Service Attacks on VoIP Environment

IP telephony refers to the use of Internet protocols to provide voice, video, and data in one integrated service over LANs, BNs, MANs, not WANs. VoIP provides three key benefits compared to traditional voice telephone services. First, it minimizes the need fro extra wiring in new buildings. Second, it provides easy movement of telephones and the ability of phone numbers to move with the individual. Finally, VoIP is generally cheaper to operate because it requires less network capacity to transmit the same voice telephone call over an increasingly digital telephone network (FitzGerald & Dennis, 2007 p. 519). Unfortunately, benefits of new electronic communications come with proportionate risks. Companies experience losses resulting from attacks on data networks. There are direct losses like economic theft, theft of trade secrets and digital data, as well as indirect losses that include loss of sales, loss of competitive advantage etc. The companies need to develop their security policies to protect their businesses. But the practice of information security has become more complex than ever. The research paper will be about the major DoS threats the company’s VoIP environment can experience as well as best countermeasures that can be used to prevent them and make the VoIP environment and, therefore, company’s networking environment more secure

Multifaceted Faculty Network Design and Management: Practice and Experience Report

We report on our experience on multidimensional aspects of our faculty's network design and management, including some unique aspects such as campus-wide VLANs and ghosting, security and monitoring, switching and routing, and others. We outline a historical perspective on certain research, design, and development decisions and discuss the network topology, its scalability, and management in detail; the services our network provides, and its evolution. We overview the security aspects of the management as well as data management and automation and the use of the data by other members of the IT group in the faculty.Comment: 19 pages, 11 figures, TOC and index; a short version presented at C3S2E'11; v6: more proofreading, index, TOC, reference

Fine-grained reasoning about the security and usability trade-off in modern security tools

Defense techniques detect or prevent attacks based on their ability to model the attacks. A balance between security and usability should always be established in any kind of defense technique. Attacks that exploit the weak points in security tools are very powerful and thus can go undetected. One source of those weak points in security tools comes when security is compromised for usability reasons, where if a security tool completely secures a system against attacks the whole system will not be usable because of the large false alarms or the very restricted policies it will create, or if the security tool decides not to secure a system against certain attacks, those attacks will simply and easily succeed. The key contribution of this dissertation is that it digs deeply into modern security tools and reasons about the inherent security and usability trade-offs based on identifying the low-level, contributing factors to known issues. This is accomplished by implementing full systems and then testing those systems in realistic scenarios. The thesis that this dissertation tests is that we can reason about security and usability trade-offs in fine-grained ways by building and testing full systems. Furthermore, this dissertation provides practical solutions and suggestions to reach a good balance between security and usability. We study two modern security tools, Dynamic Information Flow Tracking (DIFT) and Antivirus (AV) software, for their importance and wide usage. DIFT is a powerful technique that is used in various aspects of security systems. It works by tagging certain inputs and propagating the tags along with the inputs in the target system. However, current DIFT systems do not track implicit information flow because if all DIFT propagation rules are directly applied in a conservative way, the target system will be full of tagged data (a problem called overtagging) and thus useless because the tags tell us very little about the actual information flow of the system. So, current DIFT systems drop some security for usability. In this dissertation, we reason about the sources of the overtagging problem and provide practical ways to deal with it, while previous approaches have focused on abstract descriptions of the main causes of the problem based on limited experiments. The second security tool we consider in this dissertation is antivirus (AV) software. AV is a very important tool that protects systems against worms and viruses by scanning data against a database of signatures. Despite its importance and wide usage, AV has received little attention from the security research community. In this dissertation, we examine the AV internals and reason about the possibility of creating timing channel attacks against AV software. The attacker could infer information about the AV based only on the scanning time the AV spends to scan benign inputs. The other aspect of AV this dissertation explores is the low-level AV performance impact on systems. Even though the performance overhead of AV is a well known issue, the exact reasons behind this overhead are not well-studied. In this dissertation, we design a methodology that utilizes Event Tracing for Windows technology (ETW), a technology that accounts for all OS events, to reason about AV performance impact from the OS point of view. We show that the main performance impact of the AV on a task is the longer waiting time the task spends waiting on events

Peer-to-Peer Communication Across Network Address Translators

Network Address Translation (NAT) causes well-known difficulties for peer-to-peer (P2P) communication, since the peers involved may not be reachable at any globally valid IP address. Several NAT traversal techniques are known, but their documentation is slim, and data about their robustness or relative merits is slimmer. This paper documents and analyzes one of the simplest but most robust and practical NAT traversal techniques, commonly known as "hole punching." Hole punching is moderately well-understood for UDP communication, but we show how it can be reliably used to set up peer-to-peer TCP streams as well. After gathering data on the reliability of this technique on a wide variety of deployed NATs, we find that about 82% of the NATs tested support hole punching for UDP, and about 64% support hole punching for TCP streams. As NAT vendors become increasingly conscious of the needs of important P2P applications such as Voice over IP and online gaming protocols, support for hole punching is likely to increase in the future.Comment: 8 figures, 1 tabl

FriendlyMail: Confidential and Verified Emails among Friends

Despite being one of the most basic and popular Internet applications, email still largely lacks user-to-user cryptographic protections. From a research perspective, designing privacy-preserving techniques for email services is complicated by the requirement of balancing security and ease-of-use needs of everyday users. For example, users cannot be expected to manage long-term keys (e.g., PGP key-pair), or understand crypto primitives. To enable intuitive email protections for a large number of users, we design FriendlyMail by leveraging existing relationships between a sender and receiver on an online social networking (OSN) site. FriendlyMail can pro- vide integrity, authentication and confidentiality guarantees for user-selected messages among OSN friends. A confidentiality-protected email is encrypted by a randomly-generated key, and the key and hash of the encrypted content are privately shared with the receiver via the OSN site. Our implementation consists of a Firefox addon and a Facebook app, and can secure the web-based Gmail service using Facebook as the OSN site; the addon is available at: https://madiba.encs.concordia.ca/software/friendlymail/. However, the design can be implemented for preferred email/OSN services as long as the email and OSN providers are non-colluding parties. FriendlyMail is a client-end solution and does not require changes to email or OSN servers. In contrast to most other solutions, we limit our target user base to existing OSN users, to facilitate ease of adoption. In this paper, the focus of our discussion includes: the design, implementation and security analysis of the proposed solution. We acknowledge that a user study will be required to validate usability-related features of FriendlyMail. We are currently considering a comprehensive user study as separate future work; cf. past such studies of PGP (Whitten and Tygar, USENIX Security 1999), S/MIME (Garfinkel and Miller, SOUPS 2005)