![]() ![]() To reenable VT, the CPU needs to be properly power-cycled, not just reset, so this setting can only be changed from the Setup, and ideally the power cycle would need manual input as well - older machines would power down after changing the setting and require the user to press the power button again.Īs a user you would leave this setting disabled until you explicitly require it. Unless you are running virtual machines yourself, you wouldn't notice, so the BIOS allows disabling VT at first boot, so it is no longer possible for a virus to hide behind VT. The only difference you'd see, if you took the care to look, was a slight difference in reserved memory at startup compared to an uncompromised system, and that the CPU does no longer present VT interfaces to the OS. This way, it is possible to install malware that encapsulates the OS completely and thus can hide from scanners. Virtualization Technology allows running an operating system in a fully sandboxed virtual computer, and even allows exposing a different CPU type and different CPU capabilities to the OS, to the extent that it is possible to simulate a CPU that isn't virtualization capable, and that itself looks and behaves like a physical CPU. ![]() As such, Avast's option to disable this feature provides no additional security, and might actually decrease security by preventing Windows from using it in its HyperV-based sandbox. ![]() Because it requires such high privileges to use in the first place, any malware that is able to use it is already able to bypass any restrictions you set. You will not improve security by disabling hardware-assisted virtualization. Hardware-assisted virtualization (called VT-x for Intel and AMD-V for AMD) is simply a CPU feature that allows hypervisors to run at native performance, as if the hypervisor wasn't there. The hypervisor, in other words, pretends to be real hardware so the operating system running under it doesn't need to be aware of this fact. It's not a security issue so much as a feature optionally used by one theoretical kind of malware.Ī hypervisor is software which is able to run a virtual operating system underneath it. Furthermore, hardware-assisted virtualization can be used by Windows to supplement its sandbox for added security. However, this type of malware already requires extremely high privileges and is not a particular threat. In theory, hardware-assisted virtualization can make hypervisor-based rootkits possible. ![]()
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