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Privilege rings for the x86 available in protected mode. In computer science, hierarchical protection domains, [1] [2] often called protection rings, are mechanisms to protect data and functionality from faults (by improving fault tolerance) and malicious behavior (by providing computer security).
The ME is colloquially categorized as ring −3, below System Management Mode (ring −2) and the hypervisor (ring −1), all running at a higher privilege level than the kernel (ring 0). The Intel Management Engine (ME), also known as the Intel Manageability Engine, [1] [2] is an autonomous subsystem that has been incorporated in virtually all ...
System Management Mode (SMM, sometimes called ring −2 in reference to protection rings) [1] [2] is an operating mode of x86 central processor units (CPUs) in which all normal execution, including the operating system, is suspended.
Example of privilege ring usage in an operating system using all rings. In protected mode, there are four privilege levels or rings, numbered from 0 to 3, with ring 0 being the most privileged and 3 being the least. The use of rings allows for system software to restrict tasks from accessing data, call gates or executing privileged instructions ...
These instructions permit entering and exiting a virtual execution mode where the guest OS perceives itself as running with full privilege (ring 0), but the host OS remains protected. As of 2015, almost all newer server, desktop and mobile Intel processors support VT-x, with some of the Intel Atom processors as the primary exception. [24]
Privilege escalation is the act of exploiting a bug, a design flaw, or a configuration oversight in an operating system or software application to gain elevated access to resources that are normally protected from an application or user.
The principle of least privilege demonstrated by privilege rings for the Intel x86. If execution picks up after the crash by loading and running trojan code, the author of the trojan code can usurp control of all processes. The principle of least privilege forces code to run with the lowest privilege/permission level possible.
The FLAGS register is the status register that contains the current state of an x86 CPU.The size and meanings of the flag bits are architecture dependent. It usually reflects the result of arithmetic operations as well as information about restrictions placed on the CPU operation at the current time.