File Access Requests Research Articles

Dynamic user-centric access control for detection of ransomware attacks

Ransomware attacks are often catastrophic, yet existing reactive and preventative measures could only partially mitigate ransomware damage, often not in a timely manner, and often cannot prevent the novel attack vectors. Many of them were program-centric or data-centric and did not take into consideration user intention or consent. In this paper, we advocate for a dynamic approach of detecting ransomware-like behaviors by proposing a user-centric access control framework, which collects security indicators from the Operating System (OS) to deduct security metrics, compute security indicators and estimate security positions, to dynamically make access control assessments on file access requests. To demonstrate its applicability, we effectuated the principles of User-Driven Access Control (UDAC) for user intention (the goal of a user operation) and Content-Based Isolation (CBI) for user consent (the acceptance of the consequence of a user operation), and developed a proof-of-concept prototype on Windows desktop platforms. It collected information that could reveal the application identity, behavior and the OS environmental factor, before assessing whether an access request to the file system violated the principles of UDAC or CBI. Our prototype was able to raise early warnings on both attacks by real and simulated ransomware of novel vectors.

Mean-Field Analysis of Coding Versus Replication in Large Data Storage Systems

We study cloud storage systems with a very large number of files stored in a very large number of servers. In such systems, files are either replicated or coded to ensure reliability, i.e., to guarantee file recovery from server failures. This redundancy in storage can further be exploited to improve system performance (mean file-access delay) through appropriate load-balancing (routing) schemes. However, it is unclear whether coding or replication is better from a system performance perspective since the corresponding queueing analysis of such systems is, in general, quite difficult except for the trivial case when the system load asymptotically tends to zero. Here, we study the more difficult case where the system load is not asymptotically zero. Using the fact that the system size is large, we obtain a mean-field limit for the steady-state distribution of the number of file access requests waiting at each server. We then use the mean-field limit to show that, for a given storage capacity per file, coding strictly outperforms replication at all traffic loads while improving reliability. Further, the factor by which the performance improves in the heavy traffic is at least as large as in the light-traffic case. Finally, we validate these results through extensive simulations.

Collective advancements on access control scheme for multi-authority cloud storage system

In this information age, the amount of data generated by an individual and organisation is increasing exponentially. Cloud computing has come as a rescue to store and compute the data efficiently at a low cost. On the other hand, according to cloud security alliance, the threats and vulnerabilities related to cloud computing are on the rise and they may reach an uncontrollable level if cloud security inhabits the same shape. Attribute-based encryption techniques are used in several critical applications for data access control. Our proposed work enhances the security of DAC-MAC during the user registration phase by the advent of digital signature over user credentials for avoiding man-in-the-middle attack and providing non-repudiation during user registration phase. Secondly, a verification scheme based on user-privilege list for file access request is included. Lastly, by logging the user behaviours in the separate database table, the authenticity of the access node can be verified, monitored and DDoS attack can be nullified. The framework could be used for IaaS application.

Distributed Algorithms for Improving Search Efficiency in P2P Overlays

Peer-to-peer (P2P) overlay is a distributed application architecture in which peers share their resources. Peers are equally privileged, equipotent participants in the application. Several algorithms for enhancing P2P file searching have been proposed in the literature. In this paper, we have proposed a unique approach of reducing the P2P search complexity and improving search efficiency by using distributed algorithms. In our approach a peer mounts other popular peer's files and also replicates other popular files or critical files identified using a threshold value. Once a file is mounted, file access requests can be serviced by transparently retrieving the file and sending it to the requesting peer. Replication used in this work improves the file retrieval time by allowing parallel transfer. We have shown the performance analysis of our proposed approach which shows improvement in the search efficiency.

Evaluation of an Economy-Based File Replication Strategy for Malaysian Research and Education Network (MYREN) Data Grid Model

This paper discusses a simulation based file replication for Malaysian Research and Education Network (MYREN) Data Grid topology. This simulation evaluates a novel replication strategy, based on an economic model, which optimizes both the selection of replicas for running jobs and the dynamic creation of replicas in MYREN Grid sites. The optimization agents are located on MYREN Grid sites and use an auction protocol for selecting the optimal replica of a data file and a prediction function to make informed decisions about local data replication. Our primary objective of this study is to determine the optimal replication needs to be selecting when given a request by a job for a particular file in MYREN Data Grid implementation. The second objective is to trigger both replication and deletion of data files in MYREN Grid sites by analyzing the pattern of previous file requests; thereby affecting the migration of files toward sites that show a corresponding increased frequency of file-access requests. In MYREN topology, the major issue is data latency. In order to solve this issue, data replication is considered to be an important technique in reducing jobs execution. Replication involves the creation of identical copies of data files and their distribution over MYREN sites. We evaluate the replication strategy using a Data Grid simulator called OptorSim. Our simulation results showed that the technique can significantly reduce data access latency and increase the robustness of Grid application.

Evaluation of the File Redundancy in Distributed Database Systems

This paper treats the file redundancy issue in distributed database systems, asking what is the optimal number of file copies, given the ratio r of the frequency of update requests to the frequency of all file access requests (i.e., queries and updates). Formulations of this type of problem, including optimal file allocation, have been attempted by a number of authors, and some algorithms have been proposed. Although such algorithms can be used to solve particular problems, it seems difficult to draw general conclusions applicable to a wide variety of practical distributed database systems. To probe into this hard to formulate but interesting problem, our paper constructs simplified network models of distributed database systems, and computes the optimal number of file copies, as well as their locations, to minimize the communication cost. For several network types, we plot the optimal number of file copies as a function of the ratio r.

Optimizing the Performance of a Drum-Like Storage

This paper analyzes the performance, for a particular strategy, of a head-per-track type auxiliary storage system in a real-time environment. The prototype system of either fixed-head disks or drums incorporates a hardware queuer. This device attempts to always select first that request for a data transfer which will incur the shortest rotational latency relative to all other possible waiting file access requests. The queueing analysis is concerned with the tradeoff which is experienced in practice between throughput of a stochastic service device and the response time for each service request. An exact analysis of the system is shown to be totally unmanageable. Therefore, the approach is to estimate the results via physical arguments. We obtain an approximate stationary distribution for the waiting time of a file access request in the system.