Blog Post

Coding Windows Kernel Driver - InjectAll

Making the Visual Studio solution for DLL injection into all running processes.

Coding Windows Kernel Driver - InjectAll - Making the Visual Studio solution for DLL injection into all running processes.
Image courtesy of Anton Maslennikov
This article contains functions and features that are not documented by the original manufacturer. By following advice in this article, you're doing so at your own risk. The methods presented in this article may rely on internal implementation and may not work in the future.

Intro

This post will be more of a vlog post than anything else. I've spent over a week screen-recording myself while coding a Windows driver in Visual Studio. The videos should show the way how one can inject a test DLL into all running processes on Windows 10. I recorded myself coding it from start to finish, so it should be a somewhat comprehensive demo ... or, a snoozefest. 😁

In the process I also learned that coding complex algorithms and talking at the same time isn't easy, and what comes out isn't always what I would want to say had I had a quiet time to think about it 😂 So, I misspoke in a few places there. Thus, please be lenient with me if you watch it all.

And, if you are not into reading blog posts and want to start watching the video tutorial itself, check the playlist blow. Additionally, you can just download the source code alone.

Finally, let me say that if you mess up your production OS by misapplying what I showed here, it will be entirely on you. Don't blame me later!

Credit

First and foremost, I want to show my appreciation to Rbmm for sharing his original code that my solution is based on. Please give him props at his GitHub repo. He is the original author of most of the concepts that I will outline in my long video presentation here.

Quick Overview

I am not going to delve into all the nitty-gritty details in this blog post that I covered when recording my tutorial. But just to recap, here is how the process of injection into all running processes in Windows works:

  • We'll write a kernel driver to install our callback that will be invoked when a module (or DLL) is mapped into a process. We can do it using the PsSetLoadImageNotifyRoutine function.
  • Knowing the sequence how DLLs are loaded in Windows, namely, first we have ntdll.dll that loads into any user-mode process, followed by kernel32.dll, that loads into all non-native processes. Thus, if we intercept in our callback the moment when kernel32.dll is being loaded, we can inject our own DLL before it.

    Just for fun, we will call our DLL, that we will be injecting into all processes, as FAKE.DLL. And to signify its bitness, the actual file will be named FAKE64.DLL or FAKE32.DLL. It won't do much, except just write into a log file the date & time and the process that it was injected into.

    The way we will be injecting it puts a constraint on our FAKE.DLL in that it cannot rely on imports from any DLLs except for ntdll.dll. This includes C-Runtime (or CRT) and most of the C++ standard libraries.
  • To be able to bypass security mitigations in Windows, and to streamline the loading of our injected DLL, we will first create a KnownDll section out of our FAKE.DLL. This way we will be able to load our FAKE.DLL from user-mode without raising alarms from "Code Integrity Guard" (CIG) or from "Arbitrary Code Guard" (ACG).
    Note that this is not a bypass of the security mitigations in Windows, since we're employing a kernel driver for our solution.
  • The injection itself will be done through a series of Asynchronous Procedure Calls (APC) that will be initiated from the kernel mode. The sequence will go as such:
    • We will open our FAKE.DLL and create a KnownDll section out of it in the callback to the PsSetLoadImageNotifyRoutine function. We need to keep in mind that the callback will be executing from within a critical section, and thus we can't do much from it. Thus we will only quickly queue a kernel APC, using KeInitializeApc/KeInsertQueueApc functions.
    • From our APC callbacks, we will skip the KernelRoutine routine because it will be executing under APC_LEVEL IRQL.
    • But from within the NormalRoutine routine (that will be running under the PASSIVE_LEVEL IRQL) we will map our special base-independent shell-code into the target process, and queue user-mode APC that will invoke it.
      We will write our shell-code in Assembly language that will enable it to be base-independent, meaning that it will not require relocations and can run from any address in memory.
    • The shell-code will execute two simple function calls from the address space of target process:
      C++ pseudo-code
      UNICODE_STRING uS = {
      	sizeof(L"FAKE.DLL") - sizeof(WCHAR),
      	sizeof(L"FAKE.DLL"),
      	L"FAKE.DLL"
      };
      
      HANDLE h;
      LdrLoadDll(NULL, 0, &uS, &h);
      
      //BaseAddress = base address of this module
      NtUnmapViewOfSection(NtCurrentProcess(), BaseAddress);
    • After that our FAKE.DLL will be injected into the target process, that we can verify by running its DllMain function that will do some basic logging into a file for us.

This is a quick overview of the injection technique, where I omitted the peculiarities of dealing with the WOW64 processes (or 32-bit processes running on the 64-bit operating system) and other important details that I covered in detail in my video overview.

The video tutorial also covers the aspects of testing the driver in a VM, and creating a separate test C++ project to debug the injected FAKE.DLL.

Video Playlist

Note that the following is a playlist of multiple consecutive videos where I will show you the coding process from start to finish. I would recommend watching them in sequence and playing them full-screen to make sure that you can see the code:

Video Timecodes

Or, the following are time-coded segments of the tutorial that will open in a YouTube player:

  1. Installing & Setting Up Tools, Basic Concepts:
    • 1:31 - Setting up virtual machines to run driver tests in.
    • 4:22 - Setting up Visual Studio components needed to code our project.
    • 7:00 - Setting up tools in a VM:
    • 17:37 - Putting the Operating System in a VM into a test signing mode to be able to run our driver.
    • 19:52 - Creating a snapshot in the VM in case we mess up the operating system during our driver testing.
    • 21:20 - Quick overview of: physical/virtual memory, and of DLLs/modules/"sections" in the kernel space.
    • 30:34 - Overview of DLL injection with the PsSetLoadImageNotifyRoutine function.
    • 31:13 - Basic overview how we can inject our DLL into every process.
  2. Starting Windows Driver C++ Project:
    • 0:29 - Credit to Rbmm.
    • 1:01 - Recap of how we'll be injecting our FAKE.DLL into all processes: ntdll.dll, kernel32.dll, no CRT, use CFG, kernel APC.
    • 9:38 - Starting to code: Creating solution, named "InjectAll".
    • 11:03 - Starting WDM Windows driver project, named "Drv".
    • 12:26 - Adding DrvMain.cpp.
    • 13:41 - Adding DrvTypes.h.
    • 15:55 - Adding SharedDefs.h.
    • 17:14 - Adding CFunc class.
    • 19:38 - Adding DriverEntry function.
    • 21:12 - Installing the correct Windows SDK & WDK.
    • 24:04 - Installing (fighting with) Spectre-mitigated libraries for Visual Studio.
    • 26:25 - Solution to missing Spectre-mitigated libraries.
    • 28:49 - Fixing initial issues with building a driver solution.
    • 31:25 - (Erroneously) Removing test signing from building a driver.
    • 34:01 - Coding DbgPrintLine macro.
    • 38:11 - Coding DriverUnload routine.
    • 39:59 - Testing our first build of the driver.
    • 43:15 - Adding test signing back for building a driver in Visual Studio.
    • 45:02 - Was able to start and stop our first build of the driver!
  3. Beginning to Code Windows Driver:
    • 0:55 - Coding basic driver entry objects.
    • 2:43 - Setting up PsSetLoadImageNotifyRoutine callback.
    • 8:10 - Setting up OnLoadImage callback.
    • 11:15 - Coding FreeResources() function.
    • 15:30 - Coding the statement to catch kernel32.dll being loaded.
    • 19:50 - Coding CFunc::IsSuffixedUnicodeString() function.
    • 25:41 - Defining STATIC_UNICODE_STRING macro.
    • 30:01 - Coding CFunc::IsMappedByLdrLoadDll() function.
    • 40:03 - Coding CFunc::IsSpecificProcessW() function.
    • 1:10:45 - Determining if we got a WOW64 process, IoIs32bitProcess.
    • 1:12:57 - Running another driver test of what we built so far.
  4. Coding Windows Driver: Creating Section:
    • 0:39 - Quick review of what we've done so far.
    • 3:09 - Setting up CSection class.
    • 4:37 - Setting up DLL_STATS struct.
    • 6:07 - Declaring SECTION_TYPE enum.
    • 10:25 - Coding CSection::Initialize() function.
    • 12:04 - Coding CSection::GetSection() singleton function using RtlRunOnceBeginInitialize/RtlRunOnceComplete functions.
    • 32:03 - Explanation of Code Integrity Guard (CIG) and how it may affect our DLL injection.
    • 35:26 - Lowdown on KnownDlls.
    • 37:48 - Using PsInitialSystemProcess to attach to system process.
    • 45:15 - Defining the debugging TAG macro for kernel functions.
    • 47:39 - Continuing to code CSection::GetSection() function.
  5. Coding Windows Driver: Creating Section - KnownDlls:
    • 1:24 - Fixing previous bug in the CSection::GetSection() function.
    • 3:44 - Coding CSection::FreeSection() function.
    • 9:49 - Adding DBG_VERBOSE_DRV preprocessor directive for verbose debugging output.
    • 13:51 - Adding code to call CSection::FreeSection() function.
    • 17:10 - Starting to code CSection::CreateKnownDllSection() function.
    • 20:27 - Setting up to "steal" security descriptor from the existing KnownDll - kernel32.dll.
    • 21:22 - Opening existing kernel32.dll section.
    • 30:58 - Testing current build of the driver.
    • 34:14 - Adding code to call CSection::GetSection() function.
    • 39:17 - Testing again the current build of the driver.
    • 41:21 - Going back to coding CSection::CreateKnownDllSection() function.
    • 42:20 - Retrieving security descriptor from kernel32.dll section with ZwQuerySecurityObject.
    • 47:22 - Description of the OBJ_PERMANENT section object.
    • 49:48 - Differentiation of our Fake.dll section names for KnownDlls.
    • 57:22 - Allocating memory for the security descriptor from the kernel32.dll section.
  6. Coding Injected FAKE.DLL:
    • 1:18 - Adding new C++ project - FAKE.dll.
    • 3:03 - Review of restrictions of injection of our DLL into a process: ntdll.dll, kernel32.dll.
    • 9:11 - Adding new DllTypes.h file.
    • 12:15 - Removing C-Run-Time (CRT) from our FAKE.dll for the 64-bit build.
    • 15:54 - Adding Exports.def file.
    • 16:41 - Adding loadcfg.c file to enable Control Flow Guard (CFG) for our FAKE.dll.
    • 19:54 - Adding loadcfg64.asm file and x64 Assembly into it for CFG.
    • 25:29 - Removing C-Run-Time (CRT) from our FAKE.dll for the 32-bit build.
    • 28:48 - Coding loadcfg32.asm file with x86 Assembly into it for CFG.
    • 36:13 - Adding LogToFile() function using native functions from ntdll.dll.
    • 51:46 - Adding LogToFileFmt() function.
    • 59:39 - Adding code in DllMain() to run when our DLL is injected into a process.
  7. Coding Injected FAKE.DLL - TestConsole Project:
    • 1:02 - Creating TestConsole project.
    • 1:45 - Writing test code to call DllMain in our FAKE.DLL.
    • 4:36 - Ways to debug a DLL using TestConsole project.
    • 11:52 - Adding code to get pointer to TEB in DllMain.
    • 13:33 - Coding Get_TEB() function.
    • 17:30 - Coding Get_PEB() function.
    • 18:36 - Adding code to our DllMain for debugging output: process ID, process image path, current time with ntdll.dll only.
    • 28:33 - Testing our FAKE.DLL in a TestConsole with debugging output.
    • 30:57 - Explanation why we need to adjust security descriptor for the InjectAll folder for access from any process.
    • 32:37 - Adding SetDS_InjectAllFolder() debugging function.
    • 43:28 - Running our TestConsole with the SetDS_InjectAllFolder() function to adjust security descriptor on the InjectAll folder.
  8. Coding Windows Driver: Creating Section - KnownDlls (continued):
    • 0:36 - Continuing to code CSection::CreateKnownDllSection() function.
    • 3:16 - Opening our FAKE.DLL file using ZwOpenFile.
    • 13:09 - Creating a section from our FAKE.DLL using ZwCreateSection.
    • 17:57 - Filling in our DLL_STATS with created section info.
    • 18:22 - Getting our section object pointer with ObReferenceObjectByHandleWithTag.
    • 24:49 - Adjusting CSection::FreeSection() function to remove our section.
    • 27:28 - Adjusting CSection::CreateKnownDllSection() function to close permanent section correctly in case of an error.
    • 30:46 - Testing current build of the driver and two bitnesses of FAKE.DLL in a test VM.
    • 34:36 - Dealing with the error 0xC0000035 during testing.
    • 37:09 - Fixing a bug with missing CSection::Initialize() function call.
    • 48:01 - Adjusting sectionType debugging output to be more readable after a change by doing some refactoring.
    • 51:06 - Checking that security descriptor is set up correctly on the InjectAll folder.
  9. Coding Windows Driver: DLL Injection via Kernel APC:
    • 0:52 - Adding version resource to our FAKE.DLL.
    • 2:41 - Explanation why we need to use Asynchronous Procedure Calls (APC) from our driver callback.
    • 7:00 - Quick lowdown on kernel APC KernelRoutine, NormalRoutine, RundownRoutine.
    • 10:44 - Adding CSection::InjectDLL() function.
    • 14:55 - Quick lowdown on why we need to allocate from NonPagedPool when queuing KAPC.
    • 18:00 - Coding of queuing of the kernel APC with KeInitializeApc.
    • 23:38 - Using reference count on our driver object and the section object to prevent problems when queuing APC.
    • 27:42 - Inserting kernel APC with KeInsertQueueApc.
    • 33:29 - Explanation of how to dereference driver object from APC routines correctly. Why I'm coding it using JMP instruction from Assembly language.
    • 41:21 - Adding asm64.asm and asm32.asm files for APC callback stubs.
    • 43:21 - Coding RundownRoutine APC callback stub in x64 Assembly.
    • 44:44 - Coding RundownRoutine_Proc() callback procedure in C++.
    • 51:58 - Lowdown on the use of the __imp_ prefix on imported function calls from the Assembly code.
    • 58:00 - Coding KernelRoutine APC callback stub in x64 Assembly.
    • 1:01:11 - Coding KernelRoutine_Proc() callback procedure in C++.
    • 1:13:06 - Explanation of forwarding function call parameters on the stack inside KernelRoutine function written in x64 Assembly.
    • 1:18:04 - Coding NormalRoutine APC callback stub in x64 Assembly.
    • 1:19:17 - Coding NormalRoutine_Proc() callback procedure in C++.
  10. Coding Windows Driver: DLL Injection via Kernel APC (continued):
    • 0:28 - Recap of what we've coded in x64 Assembly so far.
    • 3:16 - Starting to code asm32.asm x86 Assembly file.
    • 4:00 - Coding RundownRoutine APC callback stub in x86 Assembly.
    • 7:24 - Explanation of forwarding function call parameters on the stack inside RundownRoutine function written in x86 Assembly.
    • 16:05 - Coding KernelRoutine APC callback stub in x86 Assembly.
    • 18:31 - Explanation of forwarding function call parameters on the stack inside KernelRoutine function written in x86 Assembly.
    • 22:52 - Coding NormalRoutine APC callback stub in x86 Assembly.
  11. Coding Windows Driver: DLL Injection - ShellCode x64:
    • 1:22 - Reasons for using APC to code DLL injection from our OnLoadImage kernel callback.
    • 8:05 - Coding RundownRoutine_Proc() callback.
    • 11:59 - Coding KernelRoutine_Proc() callback.
    • 14:50 - Coding NormalRoutine_Proc() callback.
    • 19:21 - Explanation of two types of code that we will put into our FAKE.DLL: Shell-code and DllMain.
    • 22:50 - Adding dll_asm64.asm file with the base-independent x64 Assembly shell-code to the FAKE.DLL project.
    • 24:33 - Coding UserModeNormalRoutine function shell-code in base-independent x64 Assembly.
    • 29:57 - Explanation why we can't use imports from external DLLs to call system functions in our base-independent shell-code.
    • 31:45 - Coding getProcAddrForMod function to resolve exported function address from a module in base-independent x64 Assembly.
    • 1:01:49 - Finishing to code UserModeNormalRoutine function in base-independent x64 Assembly.
  12. Coding Windows Driver: DLL Injection - ShellCode x86:
    • 1:07 - Adding dll_asm32.asm file with the base-independent x86 Assembly shell-code to the FAKE.DLL project.
    • 2:04 - Recap of UserModeNormalRoutine function from x64 Assembly code.
    • 4:31 - Coding getProcAddrForMod function to resolve exported function address from a module in base-independent x86 Assembly.
    • 25:55 - Coding UserModeNormalRoutine function in base-independent x86 Assembly.
    • 30:58 - Coding getStr_LdrLoadDll() function to obtain pointer to a base-independent static string.
    • 47:59 - Coding getStr_NtUnmapViewOfSection() function to obtain pointer to a base-independent static string.
    • 59:54 - Setting up UserModeNormalRoutine function to be exported as the ordinal 1 in Exports.def.
    • 1:02:33 - Explanation how to mark UserModeNormalRoutine function to bypass Export Suppression from CFG.
    • 1:05:00 - Coding exported stub function f1() to include CFG conformance for the UserModeNormalRoutine function.
  13. Coding Windows Driver: DLL Injection - Finishing up:
    • 1:13 - Adding SEARCH_TAG_W struct to keep static signature in our fake.dll.
    • 7:00 - Modifying our dummy exported function f1() to include static signature in SEARCH_TAG_W struct.
    • 13:36 - Coding CFunc::FindStringByTag() function.
    • 20:29 - Adjusting CSection::CreateKnownDllSection() function to retrieve info from our FAKE.DLL section: ZwMapViewOfSection, resolving ordinal 1 for UserModeNormalRoutine, calling CFunc::FindStringByTag and ZwQuerySection.
    • 43:06 - Adding new members into DLL_STATS with additional info about our section.
  14. Coding Windows Driver: Mapping Shell-Code & FAKE.DLL:
    • 1:21 - Review of DLL_STATS struct members.
    • 2:22 - Diagram of mapping FAKE.DLL into a process: shell-code and DllMain functions, PreferredAddress when mapping.
    • 16:07 - Creating CSection::MapSectionForShellCode() function that maps our shell-code.
    • 37:05 - Writing code to map section for shell-code in NormalRoutine_Proc() callback.
    • 42:52 - Coding CFunc::debugGetCurrentProcName() to get current process image name.
  15. Coding Windows Driver: Invoking Shell-Code & Loading FAKE.DLL:
    • 0:40 - Recap of how our Shell-code will run from the UserModeNormalRoutine() function.
    • 5:24 - Diagram with explanation of invoking kernel APCs to run our Shell-code in user-mode.
    • 14:15 - Finishing up writing kernel APC callbacks: KernelRoutine_Proc(), NormalRoutine_Proc().
    • 37:19 - Adding code to inject DLL into OnLoadImage() callback via our CSection::InjectDLL() function.
    • 40:32 - Building and testing our injection project with the notepad.exe process only.
    • 50:17 - Example of dealing with a crash in a user-mode process (notepad.exe), collecting crash dumps with WERSetup.
    • 52:40 - Adjusting NormalRoutine_Proc() to handle injection into WOW64 processes with PsWrapApcWow64Thread.
    • 56:23 - Testing injection into WOW64 notepad.exe process.
  16. Final Testing:
    • 0:49 - Building and testing our project on a 32-bit OS.
    • 11:02 - Building the project to inject into all processes.
    • 14:13 - Testing on a 64-bit Windows 10 with injection into all processes.
    • 29:05 - Testing on a 32-bit Windows 10 with injection into all processes.
  17. Testing Driver On Windows 7, Crash Dump Analysis, Bug Fixes:
    • 1:25 - Fixing a small bug.
    • 3:24 - Overview of how I used PE Internals tool.
    • 5:55 - Testing our driver on Windows 7 Pro, 64-bit OS.
    • 10:28 - Dealing with the Blue Screen Of Death (BSOD), or BugCheck on Windows 7.
    • 14:26 - Opening a crash dump file memory.dmp in WinDbg to analyze OS crash: run !analyze -v.
    • 20:17 - Fixing the issue with the crash to make our driver backward compatible with Windows 7.
    • 21:32 - Testing updated driver on Windows 7 to inject our FAKE.DLL into all running processes.
    • 28:15 - Conclusion.

Downloads

If you are interested in the source code for what I've been coding in the tutorial above:

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