Windows kernel and software security

What is Nested virtualization? ----------------------------------------------------------------------------------------------------- Nowadays, Software Security is becoming more important criteria in the industry, and in recent years, virtualization as a popular topic for protecting / attacking a software, however, most of the virtualization technology framework (bluepill-liked) is not provide an ability that let a guest virtualize one more layer, we called it "Nested Virtualization", level 2. Basic Virtual Machine Monitor Architecture ------------------------------------------------------------------------------------------------------ Figure[1] Host VMM trap any type of event which wants to monitor, such as, Interrupt, exception, privileged register access, one of this event is VMX instruction, after VMM loaded, VMM can always monitor a any one of the  VMX instructions, which provide a good chance for us. As following chart: Figure[2] VMM Life Cycle ...

Background:      Debugging with Nested-VMM hang issue when injecting nested #DB, and the infinite #PF occur, the system will be freeze.  Phenomenon: After Emulation of VMExit (L0 VMRESUME to L1), then causing VMExit Reason is 28 (CR access), and after that  the Kernel GS Base is changed. Try to intercept WRMSR and find the instruction which modify IA32_KERNEL_GS_BASE, therefore, as a follow screen capture: 0xFFFFF80002ADB369, which is in area of nt!SwapContext. Matched VMExit Reason PS. Because I take this screen capture at different time, so that address is not the same… and above: 0xFFFFF80002ADB369, there is a 0Xfffff80002a9c369 Analyze: -      Take a look at the red box in the following screen capture, the function will be directly execute WRMSR into a 0C0000102H (IA32_KERNEL_GS_BASE) MSR with actually qword ptr [r8+80h], r8 is an address of the current thread’s User Mode Scheduling Contro...