LiveCloudKd

Introduction

LiveCloudKd was the first utility to focus on Virtual Machine introspection for memory forensics purposes, it was released in 2010 after some initial research on Hyper-V v1.

This feature was later added into LiveKd 5.0 by Mark Russinovich and Ken Johnson. https://blogs.technet.microsoft.com/markrussinovich/2010/10/09/livekd-for-virtual-machine-debugging/

Maintainers

• @msuiche
• @gerhart_x

LiveCloudKd (2010)

One of the initial attribute of LiveCloudKd is that the solution was completely user-mode (!!!) due to some design flaws inside vmwp.exe (Virtual Machine Worker's process).

• The process had no isolation so it was possible to read its memory address space from another process running with administrator privileges.
• Memory Block's handles were not indexes inside an object tables but kernel mode addresses pointing to those Memory Block kernel-objects. Yes, you read that correctly. vmwp.exe used to pass kernel-mode pointers to vid.sys
• No official documentation was available regarding vmwp.exe vid.dll and the drivers winhv.sys and vid.sys BUT an Microsoft open-source project (Singularity) that was focusing on experimenting .NET as a foundation for a new Operating System leaked full headers for Vid.dll (Virtualization Interface Driver).

Each Virtual Machine has one vmwp.exe, which has one Partition Handle (PT_HANDLE) - and multiple Memory Block handles (MB_HANDLE), this is particularly true if the target Virtual Machine has the Dynamic Memory (VidDm*) feature enabled.

Quest to PT_HANDLE

First, we needed to retrive the original Partition Handle (PT_HANDLE) returned by VidCreatePartition() to the vmwp.exe. Unfortunately, no API was present to retrieve existing partition handles. But since the process was not isolated we could just look for handles within each vmwp.exe process with an object name starting with \\Device\\000000, and then we could validate each of the retrieved handles with a basic API call such as VidGetPartitionFriendlyName(). More details are available in [partition.c!IsPartitionHandle()](https://github.com/comaeio/LiveCloudKd/blob/master/hvdd/partition.c#L141):

Quest to MB_HANDLE[]

Secondly, once we recovered the valid Partition Handles corresponding to each Hyper-V Virtual Machine, we need to retrieve its Memory Block's Handles. This is where I brute-forced the memory address space of each vmwp.exe to collect all the kernel pointers before verifying if they were valid Memory Block handles or not. More details can be found in memoryblock.c!GetMemoryBlocks(). Once we have a PT_HANDLE and a MB_HANDLE we can pass them as arguments to VidReadMemoryBlockPageRange(). Overall, LiveCloudKd was using only few Vid.dll functions:

• VidDmMemoryBlockQueryTopology()
• VidQueryMemoryBlockMbpCount()
• VidGetPartitionFriendlyName()
• VidTranslateGvaToGpa()
• VidReadMemoryBlockPageRange()
• VidGetVirtualProcessorState()

From VidReadMemoryBlockPageRange() to WinDbg

Last but not least, in order to create a livekd style image on the fly I would just hook the Export Address Table (EAT) of WinDbg.exe / kd.exe. More details can be found in DumpLiveVirtualMachine()

LiveCloudKd (2018)

After discussing with @gerhart_x on why LiveCloudKd was not working anymore on the current version of Hyper-V, @gerhart_x offered to work on an expiremental feature to revive LiveCloudKd again. Unfortunately, this requires a kernel driver.

Thanks to @aionescu who pointed out to me the existence of the Windows Hypervisor Platform API (WHVP) where I noticed the presence of the ReadGuestPhysicalAddress() API which is now publicly available as of Windows 1803 (10.0.17134.48). This may be a good lead to create a current lean version of LiveCloudKd and re-enable on the fly memory forensics for Hyper-V Virtual Machines. Simpleator is a great example of an application leveraging those APIs if you want to learn more about it.

LiveCloudKd (2019+). Still beta stage!!

Added new methods for accessing guest Hyper-V VM Memory:

• ReadInterfaceWinHv - uses Hyper-V hypercall for reading guest OS memory. Slow, but robust method;
• ReadInterfaceHvmmDrvInternal - read data directly from kernel memory. Much faster, then ReadInterfaceWinHv, but uses undocument structures). See description of -m option. Default reading method is ReadInterfaceHvmmDrvInternal.
• ReadInterfaceVidAux - uses vidaux.dll library, which must be injected in vmwp.exe process, for access to Microsoft vid.dll API.
• ReadInterfaceVidNative - uses native vid.dll without driver. Can be used for Windows Server 2012\2012 R2\2016 Hyper-V.
• WriteInterfaceWinHv - uses Hyper-V hypercall for writing to guest OS memory. Use EXDi interface for it (/x or /w options). See ExdiKdSample README for more details.
• ReadInterfaceHvmmDrvInternal was tested on Windows Server 2016, Windows Server 2019 (july 2019 updates), Windows 10 x64 1803, 1809, 18362.
• ReadInterfaceVidNative was tested on Windows Server 2012, Windows Server 2012 R2, Windows Server 2016.

Tested on Full VM, docker container with Hyper-V isolation, Windows Defender Application Guard and Windows Sandbox in Windows 10 18362.

For launch:

1. hvmm.sys driver is not signed, there for start host os with TESTSIGN option (Bcdedit /set TESTSIGNING ON)
2. Place LiveCloudKd.exe, LiveCloudKdSdk.dll, hvmm.sys to WinDBG x64 folder (tested on WinDBG from WDK 1809 and WDK 1903)
3. Launch LiveCloudKd.exe with admin rights (It needs Visual Studio 2019 runtime libraries - https://aka.ms/vs/15/release/vc_redist.x64.exe)
4. Choose virtual machine (it can be Full Vm or Hyper-V container) for attaching