6,878 research outputs found
Experimental round-robin differential phase-shift quantum key distribution
In conventional quantum key distribution (QKD) protocols, security is
guaranteed by estimating the amount of leaked information through monitoring
signal disturbance, which, in practice, is generally caused by environmental
noise and device imperfections rather than eavesdropping. Such estimation
therefore tends to overrate the amount of leaked information in practice, leads
to a fundamental threshold of the bit error rate. The threshold becomes a
bottleneck of the development of practical QKD systems. In classical
communication, according to Shannon's communication theory, information can
transform through a noisy channel even if the background noise is very strong
compare to the signal and hence the threshold of the bit error rate tends to
50%. One might wonder whether a QKD scheme can also tolerate error rate as high
as 50%. The question is answered affirmatively with the recent work of
round-robin differential phase-shift (RRDPS) protocol, which breaks through the
fundamental threshold of the bit error rate and indicates another potential
direction in the field of quantum cryptography. The key challenge to realize
the RRDPS scheme lies on the measurement device, which requires a
variable-delay interferometer. The delay needs to be chosen from a set of
predetermined values randomly. Such measurement can be realized by switching
between many interferometers with different delays at a high speed in
accordance with the system repetition rate. The more delay values can be chosen
from, the higher error rate can be tolerated. By designing an optical system
with multiple switches and employing an active phase stabilization technology,
we successfully construct a variable-delay interferometer with 128 actively
selectable delays. With this measurement, we experimentally demonstrate the
RRDPS QKD protocol and obtain a final key rate of 15.54 bps via a total loss of
18 dB and 8.9% error rate.Comment: comments are welcom
Ransomware in Windows and Android Platforms
Malware proliferation and sophistication have drastically increased and
evolved continuously. Recent indiscriminate ransomware victimizations have
imposed critical needs of effective detection techniques to prevent damages.
Therefore, ransomware has drawn attention among cyberspace researchers. This
paper contributes a comprehensive overview of ransomware attacks and summarizes
existing detection and prevention techniques in both Windows and Android
platforms. Moreover, it highlights the strengths and shortcomings of those
techniques and provides a comparison between them. Furthermore, it gives
recommendations to users and system administrators.Comment: 21 pages, 7 figures, 5 table
Enabling Privacy-Preserving, Compute- and Data-Intensive Computing using Heterogeneous Trusted Execution Environment
There is an urgent demand for privacy-preserving techniques capable of
supporting compute and data intensive (CDI) computing in the era of big data.
However, none of existing TEEs can truly support CDI computing tasks, as CDI
requires high throughput accelerators like GPU and TPU but TEEs do not offer
security protection of such accelerators. This paper present HETEE
(Heterogeneous TEE), the first design of TEE capable of strongly protecting
heterogeneous computing with unsecure accelerators. HETEE is uniquely
constructed to work with today's servers, and does not require any changes for
existing commercial CPUs or accelerators. The key idea of our design runs
security controller as a stand-alone computing system to dynamically adjust the
boundary of between secure and insecure worlds through the PCIe switches,
rendering the control of an accelerator to the host OS when it is not needed
for secure computing, and shifting it back when it is. The controller is the
only trust unit in the system and it runs the custom OS and accelerator
runtimes, together with the encryption, authentication and remote attestation
components. The host server and other computing systems communicate with
controller through an in memory task queue that accommodates the computing
tasks offloaded to HETEE, in the form of encrypted and signed code and data.
Also, HETEE offers a generic and efficient programming model to the host CPU.
We have implemented the HETEE design on a hardware prototype system, and
evaluated it with large-scale Neural Networks inference and training tasks. Our
evaluations show that HETEE can easily support such secure computing tasks and
only incurs a 12.34% throughput overhead for inference and 9.87% overhead for
training on average.Comment: 16 pages, 7 figure
DALock: Distribution Aware Password Throttling
Large-scale online password guessing attacks are wide-spread and continuously
qualified as one of the top cyber-security risks. The common method for
mitigating the risk of online cracking is to lock out the user after a fixed
number () of consecutive incorrect login attempts. Selecting the value of
induces a classic security-usability trade-off. When is too large a
hacker can (quickly) break into a significant fraction of user accounts, but
when is too low we will start to annoy honest users by locking them out
after a few mistakes. Motivated by the observation that honest user mistakes
typically look quite different than the password guesses of an online attacker,
we introduce DALock a {\em distribution aware} password lockout mechanism to
reduce user annoyance while minimizing user risk. As the name suggests, DALock
is designed to be aware of the frequency and popularity of the password used
for login attacks while standard throttling mechanisms (e.g., -strikes) are
oblivious to the password distribution. In particular, DALock maintains an
extra "hit count" in addition to "strike count" for each user which is based on
(estimates of) the cumulative probability of {\em all} login attempts for that
particular account. We empirically evaluate DALock with an extensive battery of
simulations using real world password datasets. In comparison with the
traditional -strikes mechanism we find that DALock offers a superior
security/usability trade-off. For example, in one of our simulations we are
able to reduce the success rate of an attacker to (compared to
for the -strikes mechanism) whilst simultaneously reducing the unwanted
lockout rate for accounts that are not under attack to just (compared
to for the -strikes mechanism)
Bunshin: Compositing Security Mechanisms through Diversification (with Appendix)
A number of security mechanisms have been proposed to harden programs written
in unsafe languages, each of which mitigates a specific type of memory error.
Intuitively, enforcing multiple security mechanisms on a target program will
improve its overall security. However, this is not yet a viable approach in
practice because the execution slowdown caused by various security mechanisms
is often non-linearly accumulated, making the combined protection prohibitively
expensive; further, most security mechanisms are designed for independent or
isolated uses and thus are often in conflict with each other, making it
impossible to fuse them in a straightforward way.
In this paper, we present Bunshin, an N-version-based system that enables
different and even conflicting security mechanisms to be combined to secure a
program while at the same time reducing the execution slowdown. In particular,
we propose an automated mechanism to distribute runtime security checks in
multiple program variants in such a way that conflicts between security checks
are inherently eliminated and execution slowdown is minimized with parallel
execution. We also present an N-version execution engine to seamlessly
synchronize these variants so that all distributed security checks work
together to guarantee the security of a target program.Comment: To be appeared in Proceedings of the 2017 USENIX Annual Technical
Conference (ATC
Atomic Crosschain Transactions for Ethereum Private Sidechains
Public blockchains such as Ethereum and Bitcoin do not give enterprises the
privacy they need for many of their business processes. Consequently
consortiums are exploring private blockchains to keep their membership and
transactions private. Ethereum Private Sidechains is a private blockchain
technology which allows many blockchains to be operated in parallel.
Communication is needed between Ethereum Private Sidechains to allow a function
in a contract on one sidechain to execute function calls which return values
from, or update the state of, another sidechain. We propose a crosschain
technique which allows transactions to be executed atomically across
sidechains, introduce a new mechanism for proving values across sidechains,
describe a transaction locking mechanism which works in the context of
blockchain to enable atomic transactions, and a methodology for providing a
global time-out across sidechains. We outline the programming model to be used
with this technology and provide as an example, a variable amount atomic swap
contract for exchanging value between sidechains. Although this paper presents
Atomic Crosschain Transaction technology in the context of Ethereum Private
Sidechains, we discuss how this technology can be readily applied to many
blockchain systems to provide cross-blockchain transactions.Comment: 40 pages, 18 figures, 2 tables, 2 listing
Application Layer Intrusion Detection with Combination of Explicit-Rule- Based and Machine Learning Algorithms and Deployment in Cyber- Defence Program
There have been numerous works on network intrusion detection and prevention
systems, but work on application layer intrusion detection and prevention is
rare and not very mature. Intrusion detection and prevention at both network
and application layers are important for cyber-security and enterprise system
security. Since application layer intrusion is increasing day by day, it is
imperative to give adequate attention to it and use state-of-the-art algorithms
for effective detection and prevention. This paper talks about current state of
application layer intrusion detection and prevention capabilities in commercial
and open-source space and provides a path for evolution to more mature state
that will address not only enterprise system security, but also national
cyber-defence. Scalability and cost-effectiveness were important factors which
shaped the proposed solution
The never ending war in the stack and the reincarnation of ROP attacks
Return Oriented Programming (ROP) is a technique by which an attacker can
induce arbitrary behavior inside a vulnerable program without injecting a
malicious code. The continues failure of the currently deployed defenses
against ROP has made it again one of the most powerful memory corruption
attacks. ROP is also considered as one of the most flexible attacks, its level
of flexibility, unlike other code reuse attacks, can reach the Turing
completeness. Several efforts have been undertaken to study this threat and to
propose better defense mechanisms (mitigation or prevention), yet the majority
of them are not deeply reviewed nor officially implemented.Furthermore, similar
studies show that the techniques proposed to prevent ROP-based exploits usually
yield a high false-negative rate and a higher false-positive rate, not to
mention the overhead that they introduce into the protected program. The first
part of this research work aims at providing an in-depth analysis of the
currently available anti-ROP solutions (deployed and proposed), focusing on
inspecting their defense logic and summarizing their weaknesses and problems.
The second part of this work aims at introducing our proposed Indicators Of
Compromise (IOCs) that could be used to improve the detection rate of ROP
attacks. The three suggested indicators could detect these attacks at run-time
by checking the presence of some artifacts during the execution of the targeted
program.Comment: The never ending war in the stack and the reincarnation of ROP
attack
Directed Security Policies: A Stateful Network Implementation
Large systems are commonly internetworked. A security policy describes the
communication relationship between the networked entities. The security policy
defines rules, for example that A can connect to B, which results in a directed
graph. However, this policy is often implemented in the network, for example by
firewalls, such that A can establish a connection to B and all packets
belonging to established connections are allowed. This stateful implementation
is usually required for the network's functionality, but it introduces the
backflow from B to A, which might contradict the security policy. We derive
compliance criteria for a policy and its stateful implementation. In
particular, we provide a criterion to verify the lack of side effects in linear
time. Algorithms to automatically construct a stateful implementation of
security policy rules are presented, which narrows the gap between
formalization and real-world implementation. The solution scales to large
networks, which is confirmed by a large real-world case study. Its correctness
is guaranteed by the Isabelle/HOL theorem prover.Comment: In Proceedings ESSS 2014, arXiv:1405.055
ROPNN: Detection of ROP Payloads Using Deep Neural Networks
Return-oriented programming (ROP) is a code reuse attack that chains short
snippets of existing code to perform arbitrary operations on target machines.
Existing detection methods against ROP exhibit unsatisfactory detection
accuracy and/or have high runtime overhead.
In this paper, we present ROPNN, which innovatively combines address space
layout guided disassembly and deep neural networks to detect ROP payloads. The
disassembler treats application input data as code pointers and aims to find
any potential gadget chains, which are then classified by a deep neural network
as benign or malicious. Our experiments show that ROPNN has high detection rate
(99.3%) and a very low false positive rate (0.01%). ROPNN successfully detects
all of the 100 real-world ROP exploits that are collected in-the-wild, created
manually or created by ROP exploit generation tools. Additionally, ROPNN
detects all 10 ROP exploits that can bypass Bin-CFI. ROPNN is non-intrusive and
does not incur any runtime overhead to the protected program
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