2,837 research outputs found
Keys in the Clouds: Auditable Multi-device Access to Cryptographic Credentials
Personal cryptographic keys are the foundation of many secure services, but
storing these keys securely is a challenge, especially if they are used from
multiple devices. Storing keys in a centralized location, like an
Internet-accessible server, raises serious security concerns (e.g. server
compromise). Hardware-based Trusted Execution Environments (TEEs) are a
well-known solution for protecting sensitive data in untrusted environments,
and are now becoming available on commodity server platforms.
Although the idea of protecting keys using a server-side TEE is
straight-forward, in this paper we validate this approach and show that it
enables new desirable functionality. We describe the design, implementation,
and evaluation of a TEE-based Cloud Key Store (CKS), an online service for
securely generating, storing, and using personal cryptographic keys. Using
remote attestation, users receive strong assurance about the behaviour of the
CKS, and can authenticate themselves using passwords while avoiding typical
risks of password-based authentication like password theft or phishing. In
addition, this design allows users to i) define policy-based access controls
for keys; ii) delegate keys to other CKS users for a specified time and/or a
limited number of uses; and iii) audit all key usages via a secure audit log.
We have implemented a proof of concept CKS using Intel SGX and integrated this
into GnuPG on Linux and OpenKeychain on Android. Our CKS implementation
performs approximately 6,000 signature operations per second on a single
desktop PC. The latency is in the same order of magnitude as using
locally-stored keys, and 20x faster than smart cards.Comment: Extended version of a paper to appear in the 3rd Workshop on
Security, Privacy, and Identity Management in the Cloud (SECPID) 201
Web Tracking: Mechanisms, Implications, and Defenses
This articles surveys the existing literature on the methods currently used
by web services to track the user online as well as their purposes,
implications, and possible user's defenses. A significant majority of reviewed
articles and web resources are from years 2012-2014. Privacy seems to be the
Achilles' heel of today's web. Web services make continuous efforts to obtain
as much information as they can about the things we search, the sites we visit,
the people with who we contact, and the products we buy. Tracking is usually
performed for commercial purposes. We present 5 main groups of methods used for
user tracking, which are based on sessions, client storage, client cache,
fingerprinting, or yet other approaches. A special focus is placed on
mechanisms that use web caches, operational caches, and fingerprinting, as they
are usually very rich in terms of using various creative methodologies. We also
show how the users can be identified on the web and associated with their real
names, e-mail addresses, phone numbers, or even street addresses. We show why
tracking is being used and its possible implications for the users (price
discrimination, assessing financial credibility, determining insurance
coverage, government surveillance, and identity theft). For each of the
tracking methods, we present possible defenses. Apart from describing the
methods and tools used for keeping the personal data away from being tracked,
we also present several tools that were used for research purposes - their main
goal is to discover how and by which entity the users are being tracked on
their desktop computers or smartphones, provide this information to the users,
and visualize it in an accessible and easy to follow way. Finally, we present
the currently proposed future approaches to track the user and show that they
can potentially pose significant threats to the users' privacy.Comment: 29 pages, 212 reference
Spoiled Onions: Exposing Malicious Tor Exit Relays
Several hundred Tor exit relays together push more than 1 GiB/s of network
traffic. However, it is easy for exit relays to snoop and tamper with
anonymised network traffic and as all relays are run by independent volunteers,
not all of them are innocuous.
In this paper, we seek to expose malicious exit relays and document their
actions. First, we monitored the Tor network after developing a fast and
modular exit relay scanner. We implemented several scanning modules for
detecting common attacks and used them to probe all exit relays over a period
of four months. We discovered numerous malicious exit relays engaging in
different attacks. To reduce the attack surface users are exposed to, we
further discuss the design and implementation of a browser extension patch
which fetches and compares suspicious X.509 certificates over independent Tor
circuits.
Our work makes it possible to continuously monitor Tor exit relays. We are
able to detect and thwart many man-in-the-middle attacks which makes the
network safer for its users. All our code is available under a free license
Security Challenges from Abuse of Cloud Service Threat
Cloud computing is an ever-growing technology that leverages dynamic and versatile provision of computational resources and services. In spite of countless benefits that cloud service has to offer, there is always a security concern for new threats and risks. The paper provides a useful introduction to the rising security issues of Abuse of cloud service threat, which has no standard security measures to mitigate its risks and vulnerabilities. The threat can result an unbearable system gridlock and can make cloud services unavailable or even complete shutdown. The study has identified the potential challenges, as BotNet, BotCloud, Shared Technology Vulnerability and Malicious Insiders, from Abuse of cloud service threat. It has further described the attacking methods, impacts and the reasons due to the identified challenges. The study has evaluated the current available solutions and proposed mitigating security controls for the security risks and challenges from Abuse of cloud services threat
Conscript Your Friends into Larger Anonymity Sets with JavaScript
We present the design and prototype implementation of ConScript, a framework
for using JavaScript to allow casual Web users to participate in an anonymous
communication system. When a Web user visits a cooperative Web site, the site
serves a JavaScript application that instructs the browser to create and submit
"dummy" messages into the anonymity system. Users who want to send non-dummy
messages through the anonymity system use a browser plug-in to replace these
dummy messages with real messages. Creating such conscripted anonymity sets can
increase the anonymity set size available to users of remailer, e-voting, and
verifiable shuffle-style anonymity systems. We outline ConScript's
architecture, we address a number of potential attacks against ConScript, and
we discuss the ethical issues related to deploying such a system. Our
implementation results demonstrate the practicality of ConScript: a workstation
running our ConScript prototype JavaScript client generates a dummy message for
a mix-net in 81 milliseconds and it generates a dummy message for a
DoS-resistant DC-net in 156 milliseconds.Comment: An abbreviated version of this paper will appear at the WPES 2013
worksho
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