97 research outputs found
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Agamotto: Accelerating Kernel Driver Fuzzing with Lightweight Virtual Machine Checkpoints
Kernel-mode drivers are challenging to analyze for vulnerabilities, yet play a critical role in maintaining the security of OS kernels. Their wide attack surface, exposed via both the system call interface and the peripheral interface, is often found to be the most direct attack vector to compromise an OS kernel. Researchers therefore have proposed many fuzzing techniques to find vulnerabilities in kernel drivers. However, the performance of kernel fuzzers is still lacking, for reasons such as prolonged execution of kernel code, interference between test inputs, and kernel crashes. This paper proposes lightweight virtual machine checkpointing as a new primitive that enables high-throughput kernel driver fuzzing. Our key insight is that kernel driver fuzzers frequently execute similar test cases in a row, and that their performance can be improved by dynamically creating multiple checkpoints while executing test cases and skipping parts of test cases using the created checkpoints. We built a system, dubbed Agamotto, around the virtual machine checkpointing primitive and evaluated it by fuzzing the peripheral attack surface of USB and PCI drivers in Linux. The results are convincing. Agamotto improved the performance of the state-of-the-art kernel fuzzer, Syzkaller, by 66.6% on average in fuzzing 8 USB drivers, and an AFL-based PCI fuzzer by 21.6% in fuzzing 4 PCI drivers, without modifying their underlying input generation algorithm
Untangle charge-order dependent bulk states from surface effects in a topological kagome metal ScVSn
Kagome metals with charge density wave (CDW) order exhibit a broad spectrum
of intriguing quantum phenomena. The recent discovery of the novel kagome CDW
compound ScVSn has spurred significant interest. However, understanding
the interplay between CDW and the bulk electronic structure has been obscured
by a profusion of surface states and terminations in this quantum material.
Here, we employ photoemission spectroscopy and potassium dosing to elucidate
the complete bulk band structure of ScVSn, revealing multiple van Hove
singularities near the Fermi level. We surprisingly discover a robust
spin-polarized topological Dirac surface resonance state at the M point within
the two-fold van Hove singularities. Assisted by the first-principle
calculations, the temperature dependence of the - resolved ARPES spectrum
provides unequivocal evidence for the proposed
charge order over other candidates. Our
work not only enhances the understanding of the CDW-dependent bulk and surface
states in ScVSn but also establishes an essential foundation for
potential manipulation of the CDW order in kagome materials.Comment: To appear in PR
Regulation of BRCA1 stability through the tandem UBX domains of isoleucyl-tRNA synthetase 1
Aminoacyl-tRNA synthetases possess unique domains. In this study the structure of the vertebrate IARS1 and EARS1 complex reveals that vertebrate IARS1 protects the DNA repair factor BRCA1 from proteolytic degradation via its UBX-fold domain. Aminoacyl-tRNA synthetases (ARSs) have evolved to acquire various additional domains. These domains allow ARSs to communicate with other cellular proteins in order to promote non-translational functions. Vertebrate cytoplasmic isoleucyl-tRNA synthetases (IARS1s) have an uncharacterized unique domain, UNE-I. Here, we present the crystal structure of the chicken IARS1 UNE-I complexed with glutamyl-tRNA synthetase 1 (EARS1). UNE-I consists of tandem ubiquitin regulatory X (UBX) domains that interact with a distinct hairpin loop on EARS1 and protect its neighboring proteins in the multi-synthetase complex from degradation. Phosphomimetic mutation of the two serine residues in the hairpin loop releases IARS1 from the complex. IARS1 interacts with BRCA1 in the nucleus, regulates its stability by inhibiting ubiquitylation via the UBX domains, and controls DNA repair function
Design and Development of Cathode Materials for Rechargeable Batteries
Over the past two decades, rechargeable Li-ion batteries (LIBs) have been the de facto standard power source for electronic devices [...
Maintenance Optimization for Repairable Deteriorating Systems under Imperfect Preventive Maintenance
This study deals with the preventive maintenance optimization problem based on a reliability threshold. The conditional reliability threshold is used instead of the system reliability threshold. Then, the difference between the two thresholds is discussed. The hybrid failure rate model is employed to represent the effect of imperfect preventive maintenance activities. Two maintenance strategies are proposed under two types of reliability constraints. These constraints are set to consider the cost-effective maintenance strategy and to evaluate the balancing point between the expected total maintenance cost rate and the system reliability. The objective of the proposed maintenance strategies is to determine the optimal conditional reliability threshold together with the optimal number of preventive maintenance activities that minimize the expected total maintenance cost per unit time. The optimality conditions of the proposed maintenance strategies are also investigated and shown via four propositions. A numerical example is provided to illustrate the proposed preventive maintenance strategies. Some sensitivity analyses are also conducted to investigate how the parameters of the proposed model affect the optimality of preventive maintenance strategies
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