1,720,961 research outputs found
Trust Extension as a Mechanism for Secure Code Execution on Commodity Computers
No full textAs society rushes to digitize sensitive information and services, it is imperative to adopt adequate security protections. However, such protections fundamentally conflict with the benefits we expect from commodity computers. In other words, consumers and businessesvalue commodity computers because they provide good performance and an abundance offeatures at relatively low costs. Meanwhile, attempts to build secure systems from the groundup typically abandon such goals, and hence are seldom adopted .
In this dissertation, I argue that we can resolve the tension between security and featuresby leveraging the trust a user has in one device to enable her to securely use anothercommodity device or service, without sacrificing the performance and features expected ofcommodity systems. At a high level, we support this premise by developing techniques to allowa user to employ a small, trusted, portable device to securely learn what code is executingon her local computer. Rather than entrusting her data to the mountain of buggy code likelyrunning on her computer, we construct an on-demand secure execution environment whichcan perform security-sensitive tasks and handle private data in complete isolation from allother soware (and most hardware) on the system. Meanwhile, non-security-sensitive software retains the same abundance of features and performance it enjoys today.Having established an environment for secure code execution on an individual computer,we then show how to extend trust in this environment to network elements in a secure andefficient manner.this allows us to reexamine the design of network protocols and defenses,since we can now execute code on endhosts and trust the results within the network. Lastly,we extend the user’s trust onemore step to encompass computations performed on a remotehost (e.g., in the cloud). We design, analyze, and prove secure a protocol that allows a userto outsource arbitrary computations to commodity computers run by an untrusted remoteparty (or parties) who may subject the computers to both soware and hardware attacks.Our protocol guarantees that the user can both verify that the results returned are indeedthe correct results of the specied computations on the inputs provided, and protect thesecrecy of both the inputs and outputs of the computations. These guarantees are providedin a non-interactive, asymptotically optimal (with respect to CPU and bandwidth) manner.Thus, extending a user’s trust, via soware, hardware, and cryptographic techniques,allows us to provide strong security protections for both local and remote computations onsensitive data, while still preserving the performance and features of commodity computers.</p
Phoolproof Phishing Prevention
No full textPhishing, or web spoofing, is a growing problem: the Anti-Phishing Working Group (APWG) received almost 14,000 unique phishing reports in August 2005, a 56% jump over the number of reports in December 2004. For financial institutions, phishing is a particularly insidious problem, since trust forms the foundation for customer relationships, and phishing attacks undermine confidence in an institution. Phishing attacks succeed by exploiting a user’s inability to distinguish legitimate sites from spoofed sites. Prior research focuses on assisting the user in making this distinction, but they require the user to make the right security decision every time. A single mistake results in a total compromise of the user’s online account. Unfortunately, humans are ill-suited for performing the security checks necessary for secure authentication. Fundamentally, users should be authenticated using information that they cannot readily reveal to malicious parties. Our system eliminates reliance on perfect user behavior and protects a user’s account even in the presence of keyloggers and other forms of spyware. We demonstrate the practicality of our system with a working prototype. Ultimately, placing less reliance on the user during the authentication process will enhance security and eliminate many forms of fraud
SNAPP: Stateless Network-Authenticated Path Pinning
No full textThis paper examines a new building block for next-generation networks: SNAPP, or Stateless Network-Authenticated Path Pinning. SNAPP-enabled routers securely embed their routing decisions in the packet headers of a stream of traffic, effectively pinning a flow’s path between sender and receiver. A sender can use the pinned path (even if routes subsequently change) by including the path embedding in later packet headers. This architectural building block decouples routing from forwarding, which greatly enhances the availability of a path in the face of routing misconfigurations or malicious attacks. To demonstrate the extreme flexibility of SNAPP, we show how it can support a wide range of applications, including sender-controlled paths, expensive route lookups, sender anonymity, and sender accountability. Our analysis shows that SNAPP’s overhead is low, and the system is easily implemented in hardware. We believe that SNAPP is a worthy addition to the network architect’s toolbox, enabling a variety of new designs and trade-offs
Help Me Help You: Using Trustworthy Host-Based Information in the Network (CMU-CyLab-09-016)
No full textAs hardware support for improved endhost security
becomes ubiquitous, it is important to consider how
network security and performance can benefit from these
improvements. If endhosts (or at least portions of each endhost)
can be trusted, then network infrastructure no longer needs
to arduously and imprecisely reconstruct data already known
by the endhosts. Through the design of a general-purpose
architecture we call Assayer, we explore the issues in providing
trusted host-based data, including the balance between useful
information and user privacy, and the tradeoffs between
security and efficiency. We also evaluate the usefulness of such
information in three case studies.
To gain insight into the performance we could expect from
such a system, we implement and evaluate a basic Assayer
prototype. Our prototype requires fewer than 1,000 lines of
code on the endhost. Endhosts can annotate their outbound
traffic in a few microseconds, and these annotations can be
checked efficiently; even packet-level annotations on a gigabit
link can be checked with a loss in throughput of only 3.7-18.3%
Don’t Talk to Zombies: Mitigating DDoS Attacks via Attestation (CMU-CyLab-09-009)
No full textDistributed Denial-of-Service (DDoS) attacks typically originate from exploited endhosts controlled by a remote attacker. Current network-based DDoS defenses can only filter out malicious traffic based on the traffic’s inherent properties; they cannot filter based on properties of the endhost that generated the traffic. We observe that the identity of the code that has generated a packet offers powerful predicates for filtering, and we develop a secure, general architecture, Assayer, for in-network filtering based on endhost properties. Our proposed Assayer architecture leverages hardwarebased attestation mechanisms to enable legitimate endhosts to embed secure proofs of code identity in packets. Receivers can specify traffic policies, which are enforced by on-path prioritizers. We design Assayer to achieve scalability, efficiency, and incremental deployability. We implement and evaluate a basic Assayer prototype and find that the perceived application overhead, felt only during periods of significant network congestion, is less than 12%. Our simulations indicate that our architecture, even when deployed only at the victim’s ISP, provides excellent protection against a botnet of 100,000 attacking hosts
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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