Zachary Estrada

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This paper presents a solution that simultaneously addresses both reliability and security (RnS) in a monitoring framework. We identify the commonalities between reliability and security to guide the design of Hyper Tap, a hyper visor-level framework that efficiently supports both types of monitoring in virtualization environments. In Hyper Tap, the logging(More)
Many current VM monitoring approaches require guest OS modifications and are also unable to perform application level monitoring, reducing their value in a cloud setting. This paper introduces hprobes, a framework that allows one to dynamically monitor applications and operating systems inside a VM. The hprobe framework does not require any changes to the(More)
The prospect of simpler infrastructure management and affordability has garnered interest in cloud computing from bioinformaticians. However, the performance cost of adopting such an infrastructure model for bioinformatics is not fully known. In an effort to help quantify this performance cost, we ran synthetic benchmarks and measured the runtimes of two(More)
Virtualization technology has enabled powerful security monitoring techniques, such as virtual machine introspection (VMI). These monitoring techniques, however, rely on the assumed isolation of virtualized environments from the hypervisor. We show that there are still some events that can be observed that break this isolation. External observers can(More)
HyperTap is a hypervisor-level monitoring framework for virtual machines (VMs). It uses hardware architectural invariants properties defined and enforced by a hardware platform to establish the root of trust for logging data and events. HyperTap also supports continuous, event-driven VM monitoring, which enables both capturing the system state and(More)
Virtual CPU (VCPU) scheduling algorithms that efficiently manage processing-resource at the machine virtualization layer are key to facilitate resource sharing and workload consolidation in Clouds. Such algorithms are mostly inherited from pre-virtualization designs, thus need to be revamped and re-evaluated. This paper presents a simulation framework based(More)
This paper extends the concepts behind cloud services to offer hypervisor-based reliability and security monitors for cloud virtual machines. Cloud VMs can be heterogeneous and as such guest OS parameters needed for monitoring can vary across different VMs and must be obtained in some way. Past work involves running code inside the VM, which is unacceptable(More)
Numerous event-based probing methods exist for cloud computing environments allowing a hypervisor to gain insight into guest activities. Such event-based probing has been shown to be useful for detecting attacks, system hangs through watchdogs, and for inserting exploit detectors before a system can be patched, among others. Here, we illustrate how to use(More)