Virtual Machine Introspection

You can find an excellent introduction on the topic here.

In Xen 4.5, VM introspection using Intel EPT / AMD RVI hardware virtualization functionality was added building on Xen Project Hypervisors Memory Inspection APIs introduced in 2011. This addresses a number of security issues from outside the guest OS without relying on functionality that can be rendered unreliable by advanced malware. The approach works by auditing access of sensitive memory areas using HW support in guests in an unobtrusive way (or maybe better: with minimal overhead) and allows control software running within a dedicated VM to allow or deny attempts to access sensitive memory based on policy and security heuristics.

Also see:

• YouTube video (presentation)
• [vmidbg DRAKVUF - Dynamic Maklare Analysis] (contains a number of demos)
• vmidbg Enables debuggers to remotely access and manipulate VM memory, utilizing the virtual machine introspection capabilities of LibVMI
• LibVMI
• LibVMI home page