52,274 research outputs found
Shining Light On Shadow Stacks
Control-Flow Hijacking attacks are the dominant attack vector against C/C++
programs. Control-Flow Integrity (CFI) solutions mitigate these attacks on the
forward edge,i.e., indirect calls through function pointers and virtual calls.
Protecting the backward edge is left to stack canaries, which are easily
bypassed through information leaks. Shadow Stacks are a fully precise mechanism
for protecting backwards edges, and should be deployed with CFI mitigations. We
present a comprehensive analysis of all possible shadow stack mechanisms along
three axes: performance, compatibility, and security. For performance
comparisons we use SPEC CPU2006, while security and compatibility are
qualitatively analyzed. Based on our study, we renew calls for a shadow stack
design that leverages a dedicated register, resulting in low performance
overhead, and minimal memory overhead, but sacrifices compatibility. We present
case studies of our implementation of such a design, Shadesmar, on Phoronix and
Apache to demonstrate the feasibility of dedicating a general purpose register
to a security monitor on modern architectures, and the deployability of
Shadesmar. Our comprehensive analysis, including detailed case studies for our
novel design, allows compiler designers and practitioners to select the correct
shadow stack design for different usage scenarios.Comment: To Appear in IEEE Security and Privacy 201
Modeling the pulse signal by wave-shape function and analyzing by synchrosqueezing transform
We apply the recently developed adaptive non-harmonic model based on the
wave-shape function, as well as the time-frequency analysis tool called
synchrosqueezing transform (SST) to model and analyze oscillatory physiological
signals. To demonstrate how the model and algorithm work, we apply them to
study the pulse wave signal. By extracting features called the spectral pulse
signature, {and} based on functional regression, we characterize the
hemodynamics from the radial pulse wave signals recorded by the
sphygmomanometer. Analysis results suggest the potential of the proposed signal
processing approach to extract health-related hemodynamics features
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Substrate stiffness and VE-cadherin mechano-transduction coordinate to regulate endothelial monolayer integrity.
The vascular endothelium is subject to diverse mechanical cues that regulate vascular endothelial barrier function. In addition to rigidity sensing through integrin adhesions, mechanical perturbations such as changes in fluid shear stress can also activate force transduction signals at intercellular junctions. This study investigated how extracellular matrix rigidity and intercellular force transduction, activated by vascular endothelial cadherin, coordinate to regulate the integrity of endothelial monolayers. Studies used complementary mechanical measurements of endothelial monolayers grown on patterned substrates of variable stiffness. Specifically perturbing VE-cadherin receptors activated intercellular force transduction signals that increased integrin-dependent cell contractility and disrupted cell-cell and cell-matrix adhesions. Further investigations of the impact of substrate rigidity on force transduction signaling demonstrated how cells integrate extracellular mechanics cues and intercellular force transduction signals, to regulate endothelial integrity and global tissue mechanics. VE-cadherin specific signaling increased focal adhesion remodeling and cell contractility, while sustaining the overall mechanical equilibrium at the mesoscale. Conversely, increased substrate rigidity exacerbates the disruptive effects of intercellular force transduction signals, by increasing heterogeneity in monolayer stress distributions. The results provide new insights into how substrate stiffness and intercellular force transduction coordinate to regulate endothelial monolayer integrity
CYCLOSA: Decentralizing Private Web Search Through SGX-Based Browser Extensions
By regularly querying Web search engines, users (unconsciously) disclose
large amounts of their personal data as part of their search queries, among
which some might reveal sensitive information (e.g. health issues, sexual,
political or religious preferences). Several solutions exist to allow users
querying search engines while improving privacy protection. However, these
solutions suffer from a number of limitations: some are subject to user
re-identification attacks, while others lack scalability or are unable to
provide accurate results. This paper presents CYCLOSA, a secure, scalable and
accurate private Web search solution. CYCLOSA improves security by relying on
trusted execution environments (TEEs) as provided by Intel SGX. Further,
CYCLOSA proposes a novel adaptive privacy protection solution that reduces the
risk of user re- identification. CYCLOSA sends fake queries to the search
engine and dynamically adapts their count according to the sensitivity of the
user query. In addition, CYCLOSA meets scalability as it is fully
decentralized, spreading the load for distributing fake queries among other
nodes. Finally, CYCLOSA achieves accuracy of Web search as it handles the real
query and the fake queries separately, in contrast to other existing solutions
that mix fake and real query results
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